- Email: [email protected]
Lesions of the globus pallidus and striatum attenuate ketocyclazocine-induced feeding
Physiology &Behavior,Vol. 33, pp. 349-355. Copyright©Pergamon Press Ltd., 1984. Printed in the U.S.A.
0031-9384/84 $3.00 + .00
Lesions of the Globus Pallidus and Striatum Attenuate Ketocyclazocine-Induced Feeding B. A . G O S N E L L ,
J. E. M O R L E Y
A N D A . S. L E V I N E
Neuroendocrine Research Laboratory, VA Medical Center 54th St. and 48th Ave S., Min,eapolis, M N 55417 and the Departments o f Medicine and Food Science and Nutrition University o f Minnesota, Minneapolis-St. Paul, M N R e c e i v e d 16 J a n u a r y 1984 GOSNELL, B. A., J. E. MORLEY AND A. S. LEVINE. Lesions t2f the globus pallidus and striatum attenuate ketocyclazocine-inducedfeeding. PHYSIOL BEHAV 33(3) 349-355, 1984.--A large body of evidence suggests that endogenous opioids are involved in the regulation of feeding. As the striatum and globus pallidus have relatively high concentrations of opioid receptors, these areas are possible sites of action for the stimulatory effects of opiates on feeding. To test these possibilities, male rats were lesioned bilaterally in the globus pallidus or striatum. Nocturnal food intake was then measured after the subcutaneous administration of the opiate antagonist, naloxone (0-10 mg/kg). Spontaneous daytime intake was measured after the subcutaneous administration of the kappa opiate agonist ketocyclazocine (0-10 mg/kg). Neither pallidal nor striatal lesions affected the sensitivity of naloxone in reducing food intake. On the other hand, both lesioned groups were 10--100times less sensitive to the stimulatory effects of ketocyclazocine. These results suggest that the globus pallidus and striatum may be target areas for the stimulatory effects of exogenous opiates on food intake. Additionally, the relationship of these areas to the dopaminergic nigrostriatal tract suggests that feeding regulation may involve an interaction between dopaminergic and opioid systems. Globus pallidus
Striatum
Naloxone
Ketocyclazocine
T H E administration of opiate agonists induces feeding under a variety of conditions [5, 15, 17, 19, 28] and opiate antagonists reduce food intake in a variety of species [2, 9, 18, 34]. It has therefore been proposed that endogenous opioids are involved in the regulation of appetite [28,33]. Several types of opioid receptors have been identified, and endogenous opioids (and exogenous opiates) are generally selective in their binding to one of these types [l 1,21]. Agonists of the kappa opioid receptor, including the endogenous kappa ligand, dynorphin [ 13], are potent stimulators of feeding [17, 19, 25, 26]. Binding of ['~H] ethylketocyclazocine, a preferential kappa agonist, was found to be relatively high in the striatum of the guinea pig and the rat [ 12,32]. Dynorphin-like immunoreactivity is also found in the striatum and globus pallidus [3, 8, 43]. Several reports suggest that the striatum and globus pallidus may be involved in appetite regulation. Wagner and DeGroot [41] initiated feeding in sated rats by chemical stimulation of the globus pallidus with epinephrine and norepinephrine; lesions of the globus pallidus (electrolytic or chemical) were shown to reduce intake or body weight [16, 20, 22]. Infusion of d-amphetamine into the rat striatum stimulated feeding [44]. Single unit activity is evoked in the globus pallidus by food-motivated behavior [39], and in the caudate by gastric distention [35]. To determine whether the striatum and globus pallidus
Opiates
Feeding
are involved in the feeding induced by opiates, we made bilateral lesions of these two areas in rats. We then tested the effectiveness of the opiate antagonist naloxone in reducing nocturnal intakes. These tests were followed by tests with ketocyclazocine (KC), a kappa agonist which has been shown to reliably increase food intake [19,27]. A lesioninduced change in the responses to these drugs would suggest that one or both of these areas partially mediate the effects of opiates on feeding. METHOD Male Sprague-Dawley rats (228-288 g) were housed individually in stainless steel cages under a 12:12 light-dark cycle and given ad lib access to food and water except where indicated. Rats were anesthetized with Nembutal (40 mg/kg), mounted in a stereotaxic instrument and grounded by means of a rectal probe. They were given bilateral electrolytic lesions on the globus pallidus (n= 10) by passing a 2 mA current (anodal) for 10 seconds through a 30 gauge stainless steel monopolar electrode, which was insulated except at the tip, from which 0.3-0.5 mm of insulation had been scraped. Stereotaxic coordinates (in mm) were: anterior (to bregma): +0.7, lateral: -+3.1, and ventral (from dura): 5.6 [30]. F o r sham operated controls, the electrode was lowered 1 mm
349
350
GOSN['~LL, MORLEY AND Lt'~VIN[,I
FIG. 1. Coronal brain section representing typical lesions of the globus pallidus.
less than in lesioned animals and no current was passed. The wounds were closed with wound clips and the animals were allowed at least six days to recover. Prior to naloxone testing, food and water intakes were measured for the light and dark phases of a 24-hour cycle. At the beginning of the dark phase (9--10 days post-surgery), rats were given SC injections of naloxone hydrochloride at doses of 0.1, 1 and 10 mg/kg, or saline. Fifteen minutes after injections, preweighed food pellets were placed in the home cages; these pellets were then weighed and replaced 1 and 2 hours later. Other food had been removed from the cages 2 hours earlier to prevent feeding immediately prior to testing. This entire testing procedure was repeated on the next 3 days, such that each rat was tested with each naloxone dose and saline. The order in which the doses were tested varied across rats such that every dose was represented in every test session. In the early portion of the light phase (32-33 days postsurgery), rats were given SC injections of ketocyclazocine at doses of 0.1, 1 and 10 mg/kg, or vehicle (1:1 methanol: 0.1 N HCI). Pre-weighed food pellets were placed into the cages immediately following injections and intake was measured 1, 2, 4 and 6 hours later. As with naloxone testing, this procedure was repeated on the next 3 days such that every rat was tested with every dose in a counterbalanced design. These rats had been similarly tested with butorphanol tartrate 10-14 days earlier (data not reported here). Two days after the final KC trial, food and water intake were again measured for the light and dark phases of a 24-hour cycle. Another group of rats (n= 10) was given bilateral lesions (or sham lesions, n = 10) of the striatum (anterior: +2.0, lateral: +3.0, and ventral: 4.7). The lesioning procedure was the same as that described above. Naloxone trials were performed, 48 hours apart, beginning at least 10 days post surgery. Two days later, KC trials were given on four con-
secutive days. Naloxone and KC trials were identical to those given the GP lesioned animals. Twenty-four hours following the final KC trial, food and water intakes were measured for the light and dark phases of a 24 hour cycle.
Ver(fication of Lesions At the conclusion of feeding experiments, rats were deeply anesthetized with ether and perfused with a 10% sucrose-formalin ammonium bromide solution. Brains were removed, and frozen sections (40 /zm) were made through the area of the lesion and stained with a modified version of the Auletta method [45]. Data from rats with improperly placed lesions were discarded.
Statistical Analysis For each set of animals, cumulative food intakes at each time point were analyzed with a mixed-design analysis of variance (drug dose × lesion) with dosage as a repeated measures factor. When a significant dose effect was obtained, group means were compared to control means with the least significant difference test (LSD, two-tailed). The analyses of naloxone data excluded data from rats consuming 0.1 g or less in the first hour of the saline condition. RESULTS Following histological examination, data from one striatal-lesioned rat and two GP-lesioned rats were discarded because of improper placement. One additional GP-lesioned rat died before feeding data were collected. The remaining rats had bilateral, roughly symmetrical damage in the target areas. Figures 1 and 2 indicate typical lesion size and placement in GP- and striatal-lesioned rats, respectively. At the time of surgery, neither the GP lesioned nor the
KETOCYCLAZOCINE-INDUCED FEEDING
351
FIG. 2. Coronal brain section representing typical lesions of the striatum.
striatal lesioned rats were significantly different in body weight from their respective sham controls (Table 1). Approximately 18 days post surgery, GP lesioned rats weighed significantly less than the shams; striatal lesioned rats weighed approximately the same as their sham controls. At a later time (32-33 days post surgery), the weight difference between GP lesioned rats and shams was smaller and only approached significance (359.0-+11.58 g vs. 388.8+11.25 g for shams, t(15)=1.795). This second weighing coincided with the beginning of the KC trials for these rats. When first measured (6-7 days post surgery), nocturnal food and water intakes were significantly decreased in GPlesioned rats (Table 2). In the daytime, water intake was significantly increased in the lesioned rats, and food intake was elevated, though not to a significant degree. Striatal lesioned rats did not differ from shams in food or water intake for either period. When measured again (37-38 days post surgery), nocturnal food intake was only slightly lowered in GP-lesioned rats (18.07-+0.82 g vs. 20.27-+ 1.08 g for shams, N.S.) and water intake was significantly reduced (28.8_+2.17 ml vs. 34.59-+1.59 ml for shams, t(15)=2.206, p<0.05). Daytime food intakes were similar to shams (4.41_+0.62 g vs. 4.30-+0.39 g, N.S.), as were water intakes (3.81_+0.80 ml vs. 3.71-+0.51 ml, N.S.). Figure 3 summarizes the effects of naloxone on food intake. Data from one striatal lesioned rat and two rats in each sham group were discarded because the rats failed to consume more than 0.1 g in the first hour of the saline condition. In GP-lesioned rats (and shams), there was a significant dose effect at l and 2 hours, F(3,39)=4.64 and 8.40, respectively, p<0.01. Post-hoc analysis indicated that the l0 mg/kg dose decreased l and 2 hour intake in sham and lesioned animals. The 1 mg/kg dose also reduced 2 hour intake in both groups. Neither the lesion main effect nor the interaction (dose x lesion) were significant.
TABLE 1 BODY WEIGHTSAT TIME OF sUi~GERYAND 18-21 DAYSLATER Days After Surgery n
0
18-21"
GP Lesion Sham
7 10
244.00± 2 . 9 4 241.10 ± 2 . 3 8
305.29± 9.97t 345.30± 7.08
Striatal Lesion Sham
9 10
271.10 ± 6.29 262.80 ± 4 . 3 6
329.11± 6.63 325.50± 7.40
Results are expressed as means in grams + SEM. *Represents 18-21 days, as not all surgery was performed on the same day. tp
In striatal lesioned rats and their sham controls, there was a significant naloxone effect at l and 2 hours, F(3,42)=3.89 and 14.72, respectively, p<0.05. Post hoc analysis indicated that the l and l0 mg/kg doses reduced i hour intake in sham rats; none of the naloxone doses significantly reduced intake in striatal lesioned rats 60>0.05). Intakes under the various doses in these rats are similar to shams, however, and neither the lesion main effect nor the interaction were significant. Two hour cumulative intakes were significantly reduced in lesioned and sham rats by the 0. l, 1 and l0 mg/kg doses. Again, neither the lesion main effect nor the interaction were significant. Figure 4 presents mean intakes in GP-lesioned and sham rats after KC administration. There was a significant KC dose effect at l, 2, 4 and 6 hours, F(3,45)=12.36, 8,85, 9.59 and 5.12, respectively, p<0.005. In sham rats, intake was
352
GOSNELL, MORLEY AND I,EIVINE "FABLE 2 FOOD AND WATER I N T A K E S IN GP AND STRIATAL L E S I O N E D AND SHAM RATS
Food (g)
Water (ml)
n
Dark
Light
Dark
Light
GP Lesion Sham
6+ l0
17.45 _+ 2.61" 22.56 + 0.54
3.98 + 0.61 2.64 ± 0.41
28.22 +_ 2.85* 35.61 +_ 0.87
5.90 + 1.26" 3.19 ± 0.43
Striatal Lesion Sham
9 10
18.22 ± 0.83 19.25 ± 0.55
2.76 ± 0.40 3.39 + 0.35
30.50 ± 1.96 32.22 + 1.73
3.57 _+ 0.83 3.58 ± 0.39
Results are expressed as means -+ SEM. *Different from corresponding shams, p<0.05, two-tailed t-test. +Data from one rat were discarded due to an obstruction of the water spout.
A
GP Lesion n=7
4
Sham n=8
B
Striatal Lesion n=8
t HOUR
F13,51)=3.21, 3.41, and 3.08, respectively, p<0.05. This interaction approached significance at two hours, F(3,51)=2.07, p=0.116. The lesion main effect was not significant at any time point.
Sham n=8
I HOUR
DISCUSSION
NaClO.I f z
6
i
10
NaCIO.I I I0
2 HOURS __ * _
N~I Of I
I0
5
NaClO.I 1 I0
I0
2 HOURS - - - -
_
; ..,-, NaClO.I f I0
I~CI 0.1 I
NaCIO.I I I0
mTm** NoClO.I
t
I0
NALOXONE (mg/kg)
FIG. 3. One and two hour mean food intakes (+SEM) after SC injections of naloxone. A. Intake in rats with bilateral lesions of the globus paUidus and sham operated controls. B. Intake in rats with bilateral striatal lesions and sham operated controls. Asterisks indicate a significant difference from the corresponding NaCI condition, p<0.05 (two-tailed LSD procedure).
significantly increased by the 1 mg/kg dose at 1, 2, 4 and 6 hours. Additionally, the 0.1 mg/kg increased 1 hour intake, and the 10 mg/kg dose increased 4 and 6 hour cumulative intake. In GP-lesioned rats, intake was not significantly increased at any dose or time point; in fact, doses of i and 10 mg/kg significantly reduced 1 hour intake. That the lesioned rats responded to KC differently than shams is indicated by a significant dose x lesion interaction at all four time points, F(3,45)=6.79, 3.28, 5.08 and 4.65, respectively, p<0.05. The, lesion main effect was not significant at any time point. Figure 5 indicates mean intakes after KC injections in striatal lesioned and sham rats. There was a significant KC dose effect at 1, 2, 4 and 6 hours, F(3,51)=9.31, 15.71, 22.78 and 15.18, respectively, p<0.0005. In sham rats doses of 0.1 and 1 mg/kg significantly increased intake at all time points. The 10 mg/kg dose also increased 4 and 6 hour cumulative intake. In contrast, the 1 mg/kg dose increased cumulative intake only at 2 and 4 hours in striatal lesioned rats. The 10 mg/kg dose increased 4 and 6 hour intake. There was a significant dose x lesion interaction at 1, 4 and 6 hours,
Rats with lesions of the globus pallidus or striatum, as well as shams, reduced food intake in a dose-dependent manner following injections of naloxone. Neither lesion placement caused a noticeable shift in naloxone sensitivity. In contrast, globus pallidus lesions greatly attenuated the feeding response to the opiate agonist ketocyclazocine (KC). Lesions of the striatum caused a ten- to hundred-fold decrease in sensitivity to KC. Several points should be made concerning the differential effects of the lesions on naloxone and KC sensitivity. KC was tested during the day when rats normally eat little. Naloxone, however, was tested at night. An interaction between the circadian feeding rhythm and the lesion effects cannot be ruled out. It is possible that with daytime testing of deprived rats, a lesion effect on naloxone sensitivity might be observed. A circadian rhythm of the feeding response to KC has been demonstrated [27]. Another factor which must be considered is the amount of recovery time before the lesioned animals were tested. In all groups, naloxone was tested before KC; there was therefore less post-surgical recovery time before the naloxone trials began. Similarly, KC trials began 32-33 days post-surgery in rats with globus pallidus lesions compared to 18-21 days in striatal lesioned rats. This difference might explain the apparent difference in the effects of the two lesions on KC responses. Globus pallidus lesions caused slight decreases in nocturnal food and water intakes. Consistent with other studies [16, 20, 22], body weight was also reduced by pallidal lesions. Lesions of the striatum had no significant effect on nocturnal or daytime food and water intake. However, the size of the lesions was small relative to the size of the striatum; feeding deficits may have been too small to observe with the present methods. A possible explanation for the decreased responsiveness to KC in the lesioned animals is the loss of neuronal substrate upon which KC acts. Presumably reflecting the distribution of kappa receptors, the binding of [:~H]ethylketocyclazocine (EKC) is not uniform throughout the brain. In both the rat and the guinea pig, the highest levels of [:~H]-EKC binding were reported in the striatum [12,32]. The striatum and globus pallidus also contain dynorphin-like
353
KETOCYCLAZOCINE-INDUCED FEEDING
~I IHour
o Striotol Lesion (n=9)
• Sham (n=lO)
oGP Lesion (n=7)
eShom (n=lO)
43
v
I.iJ
*
Veh. Z I-4 r~
o l,o
0.1
t
C
Veh. 0.1
I0
10
v.
Veh. 0.1
i
I0
Veh. 0.1
I
I0
7
5
5
4 Hours
4
4
3
3
2
2
6 Hours,~
0 0u_
l 4 Hours
3
I
1
0
,
,
Veh. O.I
'-,
i
I0
C
,
Veh.
(~
.I
i
I I0
KETOCYCLAZOCINE (mcj/kg)
0
, , Veh. 0.1
"", f
, IO
0
I
!
Veh. 0.1
KETOCYCLAZOCINE
!
I
I
I0
(mg/kg)
FIG. 4. Mean cumulative food intake (_+SEM) in globus palliduslesioned and sham rats following SC injections of ketocyclazocine. Asterisks indicate a significant increase above the corresponding vehicle condition, p <0.05; (f) Indicates a significant decrease below corresponding vehicle condition, p<0.05 (two-tailed LSD procedure).
FIG. 5. Mean cumulative food intake (~SEM) in striatal lesioned and sham rats following SC injections of ketocyclazocine. Asterisks indicate a significant increase above corresponding vehicle condition (p<0.05, two-tailed LSD procedure).
and/or met-enkephalin like immunoreactivity [3, 8, 42, 43, 46]. It has been suggested that dynorphin is an endogenous kappa receptor ligand [13]. It is well known that lesions of the lateral hypothalamus (LH) produce symptoms of aphagia and adipsia [37]. This " L H syndrome" is also present after lesions of the globus pallidus or substantia nigra and knife cuts lateral to the hypothalamus [1, 7, 14, 22]. Aphagia also resulted from electrolytic lesions of the striatum [29]. Thus, it has been proposed that the nigrostriatal bundle plays a role in the regulation of food intake and that many of the lesions which produce aphagia may do so in part by interrupting reciprocal connections from the substantia nigra to the striatum or the closely associated pallidofugal fibers [6, 36, 40]. The nigrostriatal bundle is well known to contain dopaminergic nerve fibers. The importance of dopamine in the regulation of feeding is indicated by the findings that selective knife cuts that deplete striatal dopamine may cause severe aphagia and adipsia [1]. Conversely, the dopamine agonist bromergocryptine was found to induce feeding [26]. The .striatum and globus pallidus (a target of efferent striatal fibers) are major components of the dopamine system involved in feeding regulation. As discussed earlier, high levels of opioids and opioid receptors are also found in these areas. Dopamine-opiate interactions, therefore, might be expected. Thai et al. [38] have shown that 6-OHDA lesions of
the substantia nigra caused an increase in striatal metenkephalin levels. On the other hand, substantia nigra lesions caused a decrease in leu-enkephalin binding in the striatum [31]. Morphine treatments (IP injections) caused a hypersensitivity to dopamine [4]. Herrera-Marschitz et al. [10] found that intra-nigral injections by dynorphin caused contralateral rotation. This effect was enhanced by d-amphetamine and the authors therefore postulated that dynorphin activates dopamine neurons. Feeding induced by the dopamine agonist bromergocryptine was blocked by naloxone; conversely, feeding induced by dynorphin was blocked by the dopamine antagonists haloperidol and metoclopromide [24,26]. The initiation of feeding has therefore been proposed to be partially controlled by an interaction of dopaminergic and opioid systems [23,26]. The present f'mdings that lesions of the striatum and globus pallidus attenuate opiate-induced feeding support this proposal. If the activation of a dopaminergic system is the mechanism by which opiates induce feeding, then the interruption of this system would decrease the opiate feeding response. That naloxone sensitivity was unchanged by the lesions suggests that some aspects of the opioid feeding system are independent of striatal and pallidal influences. In summary, our lesion data suggest that the mechanism by which kappa-like opiates induce feeding requires the integrity of the striatum and the globus pallidus.
354
G O S N E [ , t . . M O R L E Y A N D I.I'~VINI' ACKNOWLEDGEMENTS We thank E. 1. DuPont de Nemours and Co., Inc. (Garden City. NY) and Sterling-Winthrop Research Institute (Rensselaer. NY) for their gifts of naloxone and ketocyclazocine, respectively. We also gratefully acknowledge Andy Valls for histological assistance and JoAnn Tallman for secretarial assistance. This research was supported by the Veterans Administration.
REFERENCES I. Alheid, G. F., L. J. McDermott, J. Kelly, A. Halaris and S. P. Grossman. Deficits in food and water intake after knife cuts that deplete striatal DA or hypothalamic NE in rats. Pharmac'ol Biochern Behav 6: 273-287, 1977. 2. Brands, B., J. A. Thornhill, M. Hirst and C. W. Gowdey. Suppression of food intake and body weight gain by naloxone in rats. Life Sci 24: 1773-1778, 1979. 3. Chesselet, M. F. and A. M. Graybiel. Met-enkephalin-like and dynorphin-like immunoreactivities of the basal ganglia of the cat. Lift, Sci 33: 37-40, 1983. 4. de la Baume, S., G. Patey, H. Marcais, P. Protais, J. Costentin and J. C. Schwartz. Changes in dopamine receptors in mouse striatum following morphine treatments. Life Sci 25: 2333-2342, 1979. 5. Gosnell, B. A., A. S. Levine and J. E. Morley. N-allylnormetazocine (SKF-10,047): The induction of feeding by a putative sigma agonist. Pharmacol Biochern Behuv 19: 737-742, 1983. 6. Grossman, S. P. The biology of motivation. Annu Rev Psyc.hol 30: 209-242, 1979. 7. Grossman, S. P. and L. Grossman. Food and water intake in rats with parasagittal knife cuts medial or lateral to the lateral hypothalamus. J Comp Physiol Psychol 74: 145-156, 1971. 8. Haber, S. N. and S. J. Watson. The comparison between enkephalin-like and dynorphin-like immunoreactivity in both monkey and human globus pallidus and substantia nigra. L~h~ Sci 33: 3-36, 1983. 9. Herman, B. H. and S. G. Holtzman. Repeated administration of naltrexone diprenorphine decreases food intake and body weight in squirrel monkeys. Life Sc'i 34: 1-12. 1984. 10. Herrera-Marschitz, M., T. Hokfelt, U. Ungerstedt and L. Terenius. Functional studies with the opioid peptide dynorphin: Acute effects of injections into the substantia nigra reticulata of naive rats. Life Sci 33: 555-558, 1983. 1 I. Herz, A. Multiple opiate receptors and their functional significance. J Neural Transm 18: 227-233, 1983. 12. Hewlett, W. A., H. Akil, W. Carlini and J. D. Barchas. Tritiated ethylketocyclazocine binding in rat brain: Differential distribution of binding sites across brain regions. Life Sci 31: 1351-1354, 1982. 13. Huidobro-Toro, J. P., K. Yoshimura, N. M. Lee, H. H. Loh and E. L. Way. Dynorphin interaction at the K-opiate site. Eur J Pharmacol 72: 265-266, 1981. 14. Iverson, S. D. The effect of surgical lesions to frontal cortex and substantia nigra on amphetamine responses in rats. Brain Res 31: 295-311, 1971. 15. Leibowitz, S. F. and L. Hot. Endorphinergic and ~-noradrenergic systems in the paraventricular nucleus. Peptides 3: 421-428, 1982. 16. Lenard, L. Sex-dependent body weight after bilateral 6-hydroxydopamine injection into the globus pallidus. Brain Res 1211: 55%568, 1977. 17. Levine, A. S. and J. E. Morley. Butorphanol tartrate induces feeding in rats. Life Sci 32: 781-785, 1983. 18. Levine, A. S., J. E. Morley, S. E. Nizielski, E. D. Plotka, B. A. Gosnell, C. J. Billington and U. S. Seal. Species diversity in opioid feeding systems. In: Recent Advances in Obesity Research: IV, edited by J. Hirsch and T. van Itallie. John Libbey & Co., Ltd., England, in press, 1984.
19. Lowy, M. T. and G. K. W. Yim. Stimulation of food intake following opiate agonists in rats but not hamsters. Psy~'hopharmuc'ology (Berlin) 81: 28-32, 1983. 20. Marshall, J. F., J. S. Richardson and P. Teitelbaum. Nigrostriatal bundle damage and the lateral hypothalamic syndrome. J Comp Physiol Psychol 87: 808-830, 1974. 21. Martin, W. R., C. G. Eades, J. A. Thompson, R. E. Huppler and P. E. Gilbert. The effects of morphine- and nalorphine-like drugs in the non-dependent and the morphine-dependent chronic spinal dog. J Pharmacol Exp Ther 197: 517-532, 1976. 22. Morgane, P. J. Alterations in feeding and drinking behavior of rats with lesions in globi pallidi. Am J Physiol 201: 420-428. 1961. 23. Morley, J. E. The neuroendocrine control of appetite: The role of the endogenous opiates, cholecystokinin, TRH, gammaamino butyric acid and the diazepam receptor. Life S~'i 27: 355-368, 1980. 24. Morley, J. E. and A. S. Levine. Opiates, dopamine and feeding. In: The Neural Basis o f Feeding and Reward, edited by B. G. Hoebel and D. Novin. Brunswick, ME: The Haer Institute, 1982, pp. 49%506. 25. Morley, J. E., A. S. Levine, B. A. Gosnell, J. Kneip and M. Grace. The kappa opioid receptor, ingestive behaviors and the obese mouse (ob/ob). Physiol Behav 31: 603-606, 1983. 26. Morley, J. E., A. S. Levine, M. Grace and J. Kneip. Dynorphin-(1-13), dopamine and feeding in rats. Pharmaco/ Bioehem Behav 16: 701-705, 1982. 27. Morley, J. E., A. S. Levine, M. Grace and J. Kneip. An investigation of the role of kappa opiate receptor agonists in the initiation of feeding. Life Sci 31: 2617-2626, 1982. 28. Morley, J. E., A. S. Levine, G. K. Yim and M. Lowy. Opioid modulation of appetite. Neurosci Biobehav Rev 7: 281-305, 1983. 29. Neill, D. B. and C. L. Linn. Deficits in consummatory responses to regulatory challenges following basal ganglia lesions in rats. Physiol Behav 14: 617-624, 1975. 30. Pellegrino, L. J., A. S. Pellegrino and A. J. Cushman. A Stereotaxic Atlas o f the Rat Brain, 2nd Edition, New York: Plenum Press, 1979. 31. Pollard, H., C. Llorens-Cartes and J. C. Schwartz. Enkephalin receptors on dopaminergic neurones in rat striatum. Nature 268: 745-747, 1977. 32. Quirion, R., A. S. Weiss and C. B. Pert. Comparative pharmacological properties and autoradiographic distribution of [3H]-ethylketocyclazocine binding sites in rat and guinea pig brain. Life Sci 33: 183-186, 1983. 33. Sanger, D. J. Endorphinergic mechanisms in the control of food and water intake. Appetite 2: 193-208, 1981. 34. Sanger, D. J., P. S. McCarthy and G. Metcalf. The effects of opiate antagonists on food intake are stereospecific. Neuropharmacology 20: 45-47, 1981. 35. Sharma, K. N. and S. Dua. Gastric-caudate relationship: Its implications in food intake. Physiologist 5: 273, 1963. 36. Stricker, E. M. and M. J. Zigmond. Effects on homeostasis of intraventricular injections of 6-hydroxydopamine in r a t s . . / Comp Physiol Psychol 86: 973-994, 1974. 37. Teitelbaum, P. and A. N. Epstein. The lateral hypothalamic syndrome: Recovery of feeding and drinking after lateral hypothalamic lesions. Psychol Rev 69: 74-90, 1962.
KETOCYCLAZOCINE-INDUCED
FEEDING
38. Thai, L. J., N. S. Sharpless, I. D. Hirschhorn, S. G. Horowitz and M. H. Makman. Striatal met-enkephalin concentration increases following nigrostriatal denervation. Biochem Pharmacol 32: 3297-3301, 1983. 39. Travis, R. P., D. L. Sparks and T. E. Hooten. Single unit responses related to sequences of food motivated behavior. Brain Res 7: 455-458, 1968. 40. Ungerstedt, U. Adipsia and aphagia after 6-hydroxydopamine induced degeneration of the nigro-striatal dopamine system. Acta Physiol Stand Suppl 367: 95-122, 1971. 4t. Wagner, J. W. and J. DeGroot. Changes in feeding behavior after intracerebral injections in the rat. Am J Physiol 204: 483487, 1963. 42. Watson, S. J., H. Akil, S. Sullivan and J. D. Barchas. ImmunocytQchemical localization of methionine enkephalin: preliminary observations. Life Sci 21: 733-738, 1977.
355
43. Weber, E., K. A. Roth and J. D. Barchas. lmmunohistochemical distribution of -neo-endorphin/dynorphin neuronal systems in rat brain: Evidence for colocalization. Proc Natl Acad Sci USA 79: 3062-3066, 1982. 44. Winn, P., S. F. Williams and L. J. Herberg. Feeding stimulated by very low doses of d-amphetamine administered systemically or by microinjection into the striatum. Psychopharmacology (Berlin) 78: 336--341, 1982. 45. Wolf, G. Elementary histology for neuropsychologists. In: Methods in Psychobiology, vol l, edited by R. D. Myers. New York: Academic Pri~ss, 1971. 46. Yang, H-Y, J. S. Hong and E. Costa. Regional distribution of leu and met enke~ahalin in rat brain. Neuropharmacology 16: 303-307, 1977.
0031-9384/84 $3.00 + .00
Lesions of the Globus Pallidus and Striatum Attenuate Ketocyclazocine-Induced Feeding B. A . G O S N E L L ,
J. E. M O R L E Y
A N D A . S. L E V I N E
Neuroendocrine Research Laboratory, VA Medical Center 54th St. and 48th Ave S., Min,eapolis, M N 55417 and the Departments o f Medicine and Food Science and Nutrition University o f Minnesota, Minneapolis-St. Paul, M N R e c e i v e d 16 J a n u a r y 1984 GOSNELL, B. A., J. E. MORLEY AND A. S. LEVINE. Lesions t2f the globus pallidus and striatum attenuate ketocyclazocine-inducedfeeding. PHYSIOL BEHAV 33(3) 349-355, 1984.--A large body of evidence suggests that endogenous opioids are involved in the regulation of feeding. As the striatum and globus pallidus have relatively high concentrations of opioid receptors, these areas are possible sites of action for the stimulatory effects of opiates on feeding. To test these possibilities, male rats were lesioned bilaterally in the globus pallidus or striatum. Nocturnal food intake was then measured after the subcutaneous administration of the opiate antagonist, naloxone (0-10 mg/kg). Spontaneous daytime intake was measured after the subcutaneous administration of the kappa opiate agonist ketocyclazocine (0-10 mg/kg). Neither pallidal nor striatal lesions affected the sensitivity of naloxone in reducing food intake. On the other hand, both lesioned groups were 10--100times less sensitive to the stimulatory effects of ketocyclazocine. These results suggest that the globus pallidus and striatum may be target areas for the stimulatory effects of exogenous opiates on food intake. Additionally, the relationship of these areas to the dopaminergic nigrostriatal tract suggests that feeding regulation may involve an interaction between dopaminergic and opioid systems. Globus pallidus
Striatum
Naloxone
Ketocyclazocine
T H E administration of opiate agonists induces feeding under a variety of conditions [5, 15, 17, 19, 28] and opiate antagonists reduce food intake in a variety of species [2, 9, 18, 34]. It has therefore been proposed that endogenous opioids are involved in the regulation of appetite [28,33]. Several types of opioid receptors have been identified, and endogenous opioids (and exogenous opiates) are generally selective in their binding to one of these types [l 1,21]. Agonists of the kappa opioid receptor, including the endogenous kappa ligand, dynorphin [ 13], are potent stimulators of feeding [17, 19, 25, 26]. Binding of ['~H] ethylketocyclazocine, a preferential kappa agonist, was found to be relatively high in the striatum of the guinea pig and the rat [ 12,32]. Dynorphin-like immunoreactivity is also found in the striatum and globus pallidus [3, 8, 43]. Several reports suggest that the striatum and globus pallidus may be involved in appetite regulation. Wagner and DeGroot [41] initiated feeding in sated rats by chemical stimulation of the globus pallidus with epinephrine and norepinephrine; lesions of the globus pallidus (electrolytic or chemical) were shown to reduce intake or body weight [16, 20, 22]. Infusion of d-amphetamine into the rat striatum stimulated feeding [44]. Single unit activity is evoked in the globus pallidus by food-motivated behavior [39], and in the caudate by gastric distention [35]. To determine whether the striatum and globus pallidus
Opiates
Feeding
are involved in the feeding induced by opiates, we made bilateral lesions of these two areas in rats. We then tested the effectiveness of the opiate antagonist naloxone in reducing nocturnal intakes. These tests were followed by tests with ketocyclazocine (KC), a kappa agonist which has been shown to reliably increase food intake [19,27]. A lesioninduced change in the responses to these drugs would suggest that one or both of these areas partially mediate the effects of opiates on feeding. METHOD Male Sprague-Dawley rats (228-288 g) were housed individually in stainless steel cages under a 12:12 light-dark cycle and given ad lib access to food and water except where indicated. Rats were anesthetized with Nembutal (40 mg/kg), mounted in a stereotaxic instrument and grounded by means of a rectal probe. They were given bilateral electrolytic lesions on the globus pallidus (n= 10) by passing a 2 mA current (anodal) for 10 seconds through a 30 gauge stainless steel monopolar electrode, which was insulated except at the tip, from which 0.3-0.5 mm of insulation had been scraped. Stereotaxic coordinates (in mm) were: anterior (to bregma): +0.7, lateral: -+3.1, and ventral (from dura): 5.6 [30]. F o r sham operated controls, the electrode was lowered 1 mm
349
350
GOSN['~LL, MORLEY AND Lt'~VIN[,I
FIG. 1. Coronal brain section representing typical lesions of the globus pallidus.
less than in lesioned animals and no current was passed. The wounds were closed with wound clips and the animals were allowed at least six days to recover. Prior to naloxone testing, food and water intakes were measured for the light and dark phases of a 24-hour cycle. At the beginning of the dark phase (9--10 days post-surgery), rats were given SC injections of naloxone hydrochloride at doses of 0.1, 1 and 10 mg/kg, or saline. Fifteen minutes after injections, preweighed food pellets were placed in the home cages; these pellets were then weighed and replaced 1 and 2 hours later. Other food had been removed from the cages 2 hours earlier to prevent feeding immediately prior to testing. This entire testing procedure was repeated on the next 3 days, such that each rat was tested with each naloxone dose and saline. The order in which the doses were tested varied across rats such that every dose was represented in every test session. In the early portion of the light phase (32-33 days postsurgery), rats were given SC injections of ketocyclazocine at doses of 0.1, 1 and 10 mg/kg, or vehicle (1:1 methanol: 0.1 N HCI). Pre-weighed food pellets were placed into the cages immediately following injections and intake was measured 1, 2, 4 and 6 hours later. As with naloxone testing, this procedure was repeated on the next 3 days such that every rat was tested with every dose in a counterbalanced design. These rats had been similarly tested with butorphanol tartrate 10-14 days earlier (data not reported here). Two days after the final KC trial, food and water intake were again measured for the light and dark phases of a 24-hour cycle. Another group of rats (n= 10) was given bilateral lesions (or sham lesions, n = 10) of the striatum (anterior: +2.0, lateral: +3.0, and ventral: 4.7). The lesioning procedure was the same as that described above. Naloxone trials were performed, 48 hours apart, beginning at least 10 days post surgery. Two days later, KC trials were given on four con-
secutive days. Naloxone and KC trials were identical to those given the GP lesioned animals. Twenty-four hours following the final KC trial, food and water intakes were measured for the light and dark phases of a 24 hour cycle.
Ver(fication of Lesions At the conclusion of feeding experiments, rats were deeply anesthetized with ether and perfused with a 10% sucrose-formalin ammonium bromide solution. Brains were removed, and frozen sections (40 /zm) were made through the area of the lesion and stained with a modified version of the Auletta method [45]. Data from rats with improperly placed lesions were discarded.
Statistical Analysis For each set of animals, cumulative food intakes at each time point were analyzed with a mixed-design analysis of variance (drug dose × lesion) with dosage as a repeated measures factor. When a significant dose effect was obtained, group means were compared to control means with the least significant difference test (LSD, two-tailed). The analyses of naloxone data excluded data from rats consuming 0.1 g or less in the first hour of the saline condition. RESULTS Following histological examination, data from one striatal-lesioned rat and two GP-lesioned rats were discarded because of improper placement. One additional GP-lesioned rat died before feeding data were collected. The remaining rats had bilateral, roughly symmetrical damage in the target areas. Figures 1 and 2 indicate typical lesion size and placement in GP- and striatal-lesioned rats, respectively. At the time of surgery, neither the GP lesioned nor the
KETOCYCLAZOCINE-INDUCED FEEDING
351
FIG. 2. Coronal brain section representing typical lesions of the striatum.
striatal lesioned rats were significantly different in body weight from their respective sham controls (Table 1). Approximately 18 days post surgery, GP lesioned rats weighed significantly less than the shams; striatal lesioned rats weighed approximately the same as their sham controls. At a later time (32-33 days post surgery), the weight difference between GP lesioned rats and shams was smaller and only approached significance (359.0-+11.58 g vs. 388.8+11.25 g for shams, t(15)=1.795). This second weighing coincided with the beginning of the KC trials for these rats. When first measured (6-7 days post surgery), nocturnal food and water intakes were significantly decreased in GPlesioned rats (Table 2). In the daytime, water intake was significantly increased in the lesioned rats, and food intake was elevated, though not to a significant degree. Striatal lesioned rats did not differ from shams in food or water intake for either period. When measured again (37-38 days post surgery), nocturnal food intake was only slightly lowered in GP-lesioned rats (18.07-+0.82 g vs. 20.27-+ 1.08 g for shams, N.S.) and water intake was significantly reduced (28.8_+2.17 ml vs. 34.59-+1.59 ml for shams, t(15)=2.206, p<0.05). Daytime food intakes were similar to shams (4.41_+0.62 g vs. 4.30-+0.39 g, N.S.), as were water intakes (3.81_+0.80 ml vs. 3.71-+0.51 ml, N.S.). Figure 3 summarizes the effects of naloxone on food intake. Data from one striatal lesioned rat and two rats in each sham group were discarded because the rats failed to consume more than 0.1 g in the first hour of the saline condition. In GP-lesioned rats (and shams), there was a significant dose effect at l and 2 hours, F(3,39)=4.64 and 8.40, respectively, p<0.01. Post-hoc analysis indicated that the l0 mg/kg dose decreased l and 2 hour intake in sham and lesioned animals. The 1 mg/kg dose also reduced 2 hour intake in both groups. Neither the lesion main effect nor the interaction (dose x lesion) were significant.
TABLE 1 BODY WEIGHTSAT TIME OF sUi~GERYAND 18-21 DAYSLATER Days After Surgery n
0
18-21"
GP Lesion Sham
7 10
244.00± 2 . 9 4 241.10 ± 2 . 3 8
305.29± 9.97t 345.30± 7.08
Striatal Lesion Sham
9 10
271.10 ± 6.29 262.80 ± 4 . 3 6
329.11± 6.63 325.50± 7.40
Results are expressed as means in grams + SEM. *Represents 18-21 days, as not all surgery was performed on the same day. tp
In striatal lesioned rats and their sham controls, there was a significant naloxone effect at l and 2 hours, F(3,42)=3.89 and 14.72, respectively, p<0.05. Post hoc analysis indicated that the l and l0 mg/kg doses reduced i hour intake in sham rats; none of the naloxone doses significantly reduced intake in striatal lesioned rats 60>0.05). Intakes under the various doses in these rats are similar to shams, however, and neither the lesion main effect nor the interaction were significant. Two hour cumulative intakes were significantly reduced in lesioned and sham rats by the 0. l, 1 and l0 mg/kg doses. Again, neither the lesion main effect nor the interaction were significant. Figure 4 presents mean intakes in GP-lesioned and sham rats after KC administration. There was a significant KC dose effect at l, 2, 4 and 6 hours, F(3,45)=12.36, 8,85, 9.59 and 5.12, respectively, p<0.005. In sham rats, intake was
352
GOSNELL, MORLEY AND I,EIVINE "FABLE 2 FOOD AND WATER I N T A K E S IN GP AND STRIATAL L E S I O N E D AND SHAM RATS
Food (g)
Water (ml)
n
Dark
Light
Dark
Light
GP Lesion Sham
6+ l0
17.45 _+ 2.61" 22.56 + 0.54
3.98 + 0.61 2.64 ± 0.41
28.22 +_ 2.85* 35.61 +_ 0.87
5.90 + 1.26" 3.19 ± 0.43
Striatal Lesion Sham
9 10
18.22 ± 0.83 19.25 ± 0.55
2.76 ± 0.40 3.39 + 0.35
30.50 ± 1.96 32.22 + 1.73
3.57 _+ 0.83 3.58 ± 0.39
Results are expressed as means -+ SEM. *Different from corresponding shams, p<0.05, two-tailed t-test. +Data from one rat were discarded due to an obstruction of the water spout.
A
GP Lesion n=7
4
Sham n=8
B
Striatal Lesion n=8
t HOUR
F13,51)=3.21, 3.41, and 3.08, respectively, p<0.05. This interaction approached significance at two hours, F(3,51)=2.07, p=0.116. The lesion main effect was not significant at any time point.
Sham n=8
I HOUR
DISCUSSION
NaClO.I f z
6
i
10
NaCIO.I I I0
2 HOURS __ * _
N~I Of I
I0
5
NaClO.I 1 I0
I0
2 HOURS - - - -
_
; ..,-, NaClO.I f I0
I~CI 0.1 I
NaCIO.I I I0
mTm** NoClO.I
t
I0
NALOXONE (mg/kg)
FIG. 3. One and two hour mean food intakes (+SEM) after SC injections of naloxone. A. Intake in rats with bilateral lesions of the globus paUidus and sham operated controls. B. Intake in rats with bilateral striatal lesions and sham operated controls. Asterisks indicate a significant difference from the corresponding NaCI condition, p<0.05 (two-tailed LSD procedure).
significantly increased by the 1 mg/kg dose at 1, 2, 4 and 6 hours. Additionally, the 0.1 mg/kg increased 1 hour intake, and the 10 mg/kg dose increased 4 and 6 hour cumulative intake. In GP-lesioned rats, intake was not significantly increased at any dose or time point; in fact, doses of i and 10 mg/kg significantly reduced 1 hour intake. That the lesioned rats responded to KC differently than shams is indicated by a significant dose x lesion interaction at all four time points, F(3,45)=6.79, 3.28, 5.08 and 4.65, respectively, p<0.05. The, lesion main effect was not significant at any time point. Figure 5 indicates mean intakes after KC injections in striatal lesioned and sham rats. There was a significant KC dose effect at 1, 2, 4 and 6 hours, F(3,51)=9.31, 15.71, 22.78 and 15.18, respectively, p<0.0005. In sham rats doses of 0.1 and 1 mg/kg significantly increased intake at all time points. The 10 mg/kg dose also increased 4 and 6 hour cumulative intake. In contrast, the 1 mg/kg dose increased cumulative intake only at 2 and 4 hours in striatal lesioned rats. The 10 mg/kg dose increased 4 and 6 hour intake. There was a significant dose x lesion interaction at 1, 4 and 6 hours,
Rats with lesions of the globus pallidus or striatum, as well as shams, reduced food intake in a dose-dependent manner following injections of naloxone. Neither lesion placement caused a noticeable shift in naloxone sensitivity. In contrast, globus pallidus lesions greatly attenuated the feeding response to the opiate agonist ketocyclazocine (KC). Lesions of the striatum caused a ten- to hundred-fold decrease in sensitivity to KC. Several points should be made concerning the differential effects of the lesions on naloxone and KC sensitivity. KC was tested during the day when rats normally eat little. Naloxone, however, was tested at night. An interaction between the circadian feeding rhythm and the lesion effects cannot be ruled out. It is possible that with daytime testing of deprived rats, a lesion effect on naloxone sensitivity might be observed. A circadian rhythm of the feeding response to KC has been demonstrated [27]. Another factor which must be considered is the amount of recovery time before the lesioned animals were tested. In all groups, naloxone was tested before KC; there was therefore less post-surgical recovery time before the naloxone trials began. Similarly, KC trials began 32-33 days post-surgery in rats with globus pallidus lesions compared to 18-21 days in striatal lesioned rats. This difference might explain the apparent difference in the effects of the two lesions on KC responses. Globus pallidus lesions caused slight decreases in nocturnal food and water intakes. Consistent with other studies [16, 20, 22], body weight was also reduced by pallidal lesions. Lesions of the striatum had no significant effect on nocturnal or daytime food and water intake. However, the size of the lesions was small relative to the size of the striatum; feeding deficits may have been too small to observe with the present methods. A possible explanation for the decreased responsiveness to KC in the lesioned animals is the loss of neuronal substrate upon which KC acts. Presumably reflecting the distribution of kappa receptors, the binding of [:~H]ethylketocyclazocine (EKC) is not uniform throughout the brain. In both the rat and the guinea pig, the highest levels of [:~H]-EKC binding were reported in the striatum [12,32]. The striatum and globus pallidus also contain dynorphin-like
353
KETOCYCLAZOCINE-INDUCED FEEDING
~I IHour
o Striotol Lesion (n=9)
• Sham (n=lO)
oGP Lesion (n=7)
eShom (n=lO)
43
v
I.iJ
*
Veh. Z I-4 r~
o l,o
0.1
t
C
Veh. 0.1
I0
10
v.
Veh. 0.1
i
I0
Veh. 0.1
I
I0
7
5
5
4 Hours
4
4
3
3
2
2
6 Hours,~
0 0u_
l 4 Hours
3
I
1
0
,
,
Veh. O.I
'-,
i
I0
C
,
Veh.
(~
.I
i
I I0
KETOCYCLAZOCINE (mcj/kg)
0
, , Veh. 0.1
"", f
, IO
0
I
!
Veh. 0.1
KETOCYCLAZOCINE
!
I
I
I0
(mg/kg)
FIG. 4. Mean cumulative food intake (_+SEM) in globus palliduslesioned and sham rats following SC injections of ketocyclazocine. Asterisks indicate a significant increase above the corresponding vehicle condition, p <0.05; (f) Indicates a significant decrease below corresponding vehicle condition, p<0.05 (two-tailed LSD procedure).
FIG. 5. Mean cumulative food intake (~SEM) in striatal lesioned and sham rats following SC injections of ketocyclazocine. Asterisks indicate a significant increase above corresponding vehicle condition (p<0.05, two-tailed LSD procedure).
and/or met-enkephalin like immunoreactivity [3, 8, 42, 43, 46]. It has been suggested that dynorphin is an endogenous kappa receptor ligand [13]. It is well known that lesions of the lateral hypothalamus (LH) produce symptoms of aphagia and adipsia [37]. This " L H syndrome" is also present after lesions of the globus pallidus or substantia nigra and knife cuts lateral to the hypothalamus [1, 7, 14, 22]. Aphagia also resulted from electrolytic lesions of the striatum [29]. Thus, it has been proposed that the nigrostriatal bundle plays a role in the regulation of food intake and that many of the lesions which produce aphagia may do so in part by interrupting reciprocal connections from the substantia nigra to the striatum or the closely associated pallidofugal fibers [6, 36, 40]. The nigrostriatal bundle is well known to contain dopaminergic nerve fibers. The importance of dopamine in the regulation of feeding is indicated by the findings that selective knife cuts that deplete striatal dopamine may cause severe aphagia and adipsia [1]. Conversely, the dopamine agonist bromergocryptine was found to induce feeding [26]. The .striatum and globus pallidus (a target of efferent striatal fibers) are major components of the dopamine system involved in feeding regulation. As discussed earlier, high levels of opioids and opioid receptors are also found in these areas. Dopamine-opiate interactions, therefore, might be expected. Thai et al. [38] have shown that 6-OHDA lesions of
the substantia nigra caused an increase in striatal metenkephalin levels. On the other hand, substantia nigra lesions caused a decrease in leu-enkephalin binding in the striatum [31]. Morphine treatments (IP injections) caused a hypersensitivity to dopamine [4]. Herrera-Marschitz et al. [10] found that intra-nigral injections by dynorphin caused contralateral rotation. This effect was enhanced by d-amphetamine and the authors therefore postulated that dynorphin activates dopamine neurons. Feeding induced by the dopamine agonist bromergocryptine was blocked by naloxone; conversely, feeding induced by dynorphin was blocked by the dopamine antagonists haloperidol and metoclopromide [24,26]. The initiation of feeding has therefore been proposed to be partially controlled by an interaction of dopaminergic and opioid systems [23,26]. The present f'mdings that lesions of the striatum and globus pallidus attenuate opiate-induced feeding support this proposal. If the activation of a dopaminergic system is the mechanism by which opiates induce feeding, then the interruption of this system would decrease the opiate feeding response. That naloxone sensitivity was unchanged by the lesions suggests that some aspects of the opioid feeding system are independent of striatal and pallidal influences. In summary, our lesion data suggest that the mechanism by which kappa-like opiates induce feeding requires the integrity of the striatum and the globus pallidus.
354
G O S N E [ , t . . M O R L E Y A N D I.I'~VINI' ACKNOWLEDGEMENTS We thank E. 1. DuPont de Nemours and Co., Inc. (Garden City. NY) and Sterling-Winthrop Research Institute (Rensselaer. NY) for their gifts of naloxone and ketocyclazocine, respectively. We also gratefully acknowledge Andy Valls for histological assistance and JoAnn Tallman for secretarial assistance. This research was supported by the Veterans Administration.
REFERENCES I. Alheid, G. F., L. J. McDermott, J. Kelly, A. Halaris and S. P. Grossman. Deficits in food and water intake after knife cuts that deplete striatal DA or hypothalamic NE in rats. Pharmac'ol Biochern Behav 6: 273-287, 1977. 2. Brands, B., J. A. Thornhill, M. Hirst and C. W. Gowdey. Suppression of food intake and body weight gain by naloxone in rats. Life Sci 24: 1773-1778, 1979. 3. Chesselet, M. F. and A. M. Graybiel. Met-enkephalin-like and dynorphin-like immunoreactivities of the basal ganglia of the cat. Lift, Sci 33: 37-40, 1983. 4. de la Baume, S., G. Patey, H. Marcais, P. Protais, J. Costentin and J. C. Schwartz. Changes in dopamine receptors in mouse striatum following morphine treatments. Life Sci 25: 2333-2342, 1979. 5. Gosnell, B. A., A. S. Levine and J. E. Morley. N-allylnormetazocine (SKF-10,047): The induction of feeding by a putative sigma agonist. Pharmacol Biochern Behuv 19: 737-742, 1983. 6. Grossman, S. P. The biology of motivation. Annu Rev Psyc.hol 30: 209-242, 1979. 7. Grossman, S. P. and L. Grossman. Food and water intake in rats with parasagittal knife cuts medial or lateral to the lateral hypothalamus. J Comp Physiol Psychol 74: 145-156, 1971. 8. Haber, S. N. and S. J. Watson. The comparison between enkephalin-like and dynorphin-like immunoreactivity in both monkey and human globus pallidus and substantia nigra. L~h~ Sci 33: 3-36, 1983. 9. Herman, B. H. and S. G. Holtzman. Repeated administration of naltrexone diprenorphine decreases food intake and body weight in squirrel monkeys. Life Sc'i 34: 1-12. 1984. 10. Herrera-Marschitz, M., T. Hokfelt, U. Ungerstedt and L. Terenius. Functional studies with the opioid peptide dynorphin: Acute effects of injections into the substantia nigra reticulata of naive rats. Life Sci 33: 555-558, 1983. 1 I. Herz, A. Multiple opiate receptors and their functional significance. J Neural Transm 18: 227-233, 1983. 12. Hewlett, W. A., H. Akil, W. Carlini and J. D. Barchas. Tritiated ethylketocyclazocine binding in rat brain: Differential distribution of binding sites across brain regions. Life Sci 31: 1351-1354, 1982. 13. Huidobro-Toro, J. P., K. Yoshimura, N. M. Lee, H. H. Loh and E. L. Way. Dynorphin interaction at the K-opiate site. Eur J Pharmacol 72: 265-266, 1981. 14. Iverson, S. D. The effect of surgical lesions to frontal cortex and substantia nigra on amphetamine responses in rats. Brain Res 31: 295-311, 1971. 15. Leibowitz, S. F. and L. Hot. Endorphinergic and ~-noradrenergic systems in the paraventricular nucleus. Peptides 3: 421-428, 1982. 16. Lenard, L. Sex-dependent body weight after bilateral 6-hydroxydopamine injection into the globus pallidus. Brain Res 1211: 55%568, 1977. 17. Levine, A. S. and J. E. Morley. Butorphanol tartrate induces feeding in rats. Life Sci 32: 781-785, 1983. 18. Levine, A. S., J. E. Morley, S. E. Nizielski, E. D. Plotka, B. A. Gosnell, C. J. Billington and U. S. Seal. Species diversity in opioid feeding systems. In: Recent Advances in Obesity Research: IV, edited by J. Hirsch and T. van Itallie. John Libbey & Co., Ltd., England, in press, 1984.
19. Lowy, M. T. and G. K. W. Yim. Stimulation of food intake following opiate agonists in rats but not hamsters. Psy~'hopharmuc'ology (Berlin) 81: 28-32, 1983. 20. Marshall, J. F., J. S. Richardson and P. Teitelbaum. Nigrostriatal bundle damage and the lateral hypothalamic syndrome. J Comp Physiol Psychol 87: 808-830, 1974. 21. Martin, W. R., C. G. Eades, J. A. Thompson, R. E. Huppler and P. E. Gilbert. The effects of morphine- and nalorphine-like drugs in the non-dependent and the morphine-dependent chronic spinal dog. J Pharmacol Exp Ther 197: 517-532, 1976. 22. Morgane, P. J. Alterations in feeding and drinking behavior of rats with lesions in globi pallidi. Am J Physiol 201: 420-428. 1961. 23. Morley, J. E. The neuroendocrine control of appetite: The role of the endogenous opiates, cholecystokinin, TRH, gammaamino butyric acid and the diazepam receptor. Life S~'i 27: 355-368, 1980. 24. Morley, J. E. and A. S. Levine. Opiates, dopamine and feeding. In: The Neural Basis o f Feeding and Reward, edited by B. G. Hoebel and D. Novin. Brunswick, ME: The Haer Institute, 1982, pp. 49%506. 25. Morley, J. E., A. S. Levine, B. A. Gosnell, J. Kneip and M. Grace. The kappa opioid receptor, ingestive behaviors and the obese mouse (ob/ob). Physiol Behav 31: 603-606, 1983. 26. Morley, J. E., A. S. Levine, M. Grace and J. Kneip. Dynorphin-(1-13), dopamine and feeding in rats. Pharmaco/ Bioehem Behav 16: 701-705, 1982. 27. Morley, J. E., A. S. Levine, M. Grace and J. Kneip. An investigation of the role of kappa opiate receptor agonists in the initiation of feeding. Life Sci 31: 2617-2626, 1982. 28. Morley, J. E., A. S. Levine, G. K. Yim and M. Lowy. Opioid modulation of appetite. Neurosci Biobehav Rev 7: 281-305, 1983. 29. Neill, D. B. and C. L. Linn. Deficits in consummatory responses to regulatory challenges following basal ganglia lesions in rats. Physiol Behav 14: 617-624, 1975. 30. Pellegrino, L. J., A. S. Pellegrino and A. J. Cushman. A Stereotaxic Atlas o f the Rat Brain, 2nd Edition, New York: Plenum Press, 1979. 31. Pollard, H., C. Llorens-Cartes and J. C. Schwartz. Enkephalin receptors on dopaminergic neurones in rat striatum. Nature 268: 745-747, 1977. 32. Quirion, R., A. S. Weiss and C. B. Pert. Comparative pharmacological properties and autoradiographic distribution of [3H]-ethylketocyclazocine binding sites in rat and guinea pig brain. Life Sci 33: 183-186, 1983. 33. Sanger, D. J. Endorphinergic mechanisms in the control of food and water intake. Appetite 2: 193-208, 1981. 34. Sanger, D. J., P. S. McCarthy and G. Metcalf. The effects of opiate antagonists on food intake are stereospecific. Neuropharmacology 20: 45-47, 1981. 35. Sharma, K. N. and S. Dua. Gastric-caudate relationship: Its implications in food intake. Physiologist 5: 273, 1963. 36. Stricker, E. M. and M. J. Zigmond. Effects on homeostasis of intraventricular injections of 6-hydroxydopamine in r a t s . . / Comp Physiol Psychol 86: 973-994, 1974. 37. Teitelbaum, P. and A. N. Epstein. The lateral hypothalamic syndrome: Recovery of feeding and drinking after lateral hypothalamic lesions. Psychol Rev 69: 74-90, 1962.
KETOCYCLAZOCINE-INDUCED
FEEDING
38. Thai, L. J., N. S. Sharpless, I. D. Hirschhorn, S. G. Horowitz and M. H. Makman. Striatal met-enkephalin concentration increases following nigrostriatal denervation. Biochem Pharmacol 32: 3297-3301, 1983. 39. Travis, R. P., D. L. Sparks and T. E. Hooten. Single unit responses related to sequences of food motivated behavior. Brain Res 7: 455-458, 1968. 40. Ungerstedt, U. Adipsia and aphagia after 6-hydroxydopamine induced degeneration of the nigro-striatal dopamine system. Acta Physiol Stand Suppl 367: 95-122, 1971. 4t. Wagner, J. W. and J. DeGroot. Changes in feeding behavior after intracerebral injections in the rat. Am J Physiol 204: 483487, 1963. 42. Watson, S. J., H. Akil, S. Sullivan and J. D. Barchas. ImmunocytQchemical localization of methionine enkephalin: preliminary observations. Life Sci 21: 733-738, 1977.
355
43. Weber, E., K. A. Roth and J. D. Barchas. lmmunohistochemical distribution of -neo-endorphin/dynorphin neuronal systems in rat brain: Evidence for colocalization. Proc Natl Acad Sci USA 79: 3062-3066, 1982. 44. Winn, P., S. F. Williams and L. J. Herberg. Feeding stimulated by very low doses of d-amphetamine administered systemically or by microinjection into the striatum. Psychopharmacology (Berlin) 78: 336--341, 1982. 45. Wolf, G. Elementary histology for neuropsychologists. In: Methods in Psychobiology, vol l, edited by R. D. Myers. New York: Academic Pri~ss, 1971. 46. Yang, H-Y, J. S. Hong and E. Costa. Regional distribution of leu and met enke~ahalin in rat brain. Neuropharmacology 16: 303-307, 1977.