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Effects of diazepam and ripazepam on two measures of adjunctive drinking in rats
Pharmacology Biochemistry & Behavior. Vol. 5, pp. 139-142. Copyright ,.: 1976 by ANKHO International Inc. All rights of reproduction in an',' forrn reserved. Printed in the U.S.A.
Effects of Diazepam and Ripazepam on Two Measures of Adjunctive Drinking in Rats' D. J. S A N G E R z AND D. E. B L A C K M A N Department ~ff"Psycholog3,, University o f Birmingham, P.O. Box 363, Birmingham, B15 2TT, England {Received 20 O c t o b e r 1975) SANGER, D. J. AND I). I'. BLACKMAN. l',ffects of diazepam and ripazepam on two measures o]ad]unctive drinking in rats. PIIARMAC. BI(X?IIEM. BtSHAV. 5(2) 139 142, 1976. Four rats were maintaincd at 85% of their pre-experimental body weights and were given daily I hr sessions during which they were each placed in a test chamber in which a 45 mg food pellet was delivered regularly every rain independently of behavior. During these sessions water spouts were available to the rats and all 4 animals developed high levels of adjunctive drinking, a burst of licking typically following the consumption of each food pellet. This behavior was found to be sensitive to the effects of diazepam and ripazepam. Small doses of both drugs increased the volume of water consumed druing a session. The number of licks was not increased to the same extent, however. Larger doses of both drugs resulted in decreased numbers of licks and decreased water intake although licking appeared on several occasions to be mort sensitive than water intake to this action of the drugs. A possible explanation of these effects is that the drugs affected lhe topography of the rats' licking at the water spouts. Whatever the mechanism inw~lvcd, however, these results suggest that in such experiments measures of both water intake and number of licks should be obtained. Diazepam
Ripazepam
Adjunctive drinking
Licking
WHEN food deprived animals receive small p o r t i o n s o f food delivered i n t e r m i t t e n t l y they have been observed to drink large q u a n t i t i e s o f water, a burst of drinking typically occurring after the c o n s u m p t i o n of each food p o r t i o n [ 5 ] . This behavior has been described as s c h e d u l e - i n d u c e d polydipsia and it has been suggested that it is one o f a class of behaviors which Falk [7] has n a m e d adjunctive. Several reports have described the e f f e c t s o f a m p h e t a mines on adjunctive drinking, w h i c h is generally a t t e n u a t e d by the a d m i n i s t r a t i o n of these drugs 16, 11, 14, 15, 1~)1. Wayner et al. [ l g ] , h o w e v e r , observed increases in adjunctive drinking after the a d m i n i s t r a t i o n o f small doses o f d - a m p h e t a m i n e to a rat with a relatively low baseline rate of drinking. Decreases in adjunctive drinking have also been r e p o r t e d after a d m i n i s t r a t i o n of p e n t o b a r b i t a l 16,151, a t r o p i n e [3] and e t h a n o l [g] and drinking has been f o u n d to be increased by certain doses o f zx~ THC [ 17]. R e c e n t l y a n u m b e r of e x p e r i m e n t s have investigated the actions of c h l o r d i a z e p o x i d e on adjunctive drinking. McKearney [11] sludied the adjunctive licking o f rats which were m a i n t a i n e d on a fixed-interval schedule o f r e i n f o r c e m e n t for which the o p e r a n t response was also licking the water tube. C h l o r d i a z e p o x i d c was f o u n d to have little effect on or even to decrease the n u m b e r o f adjunctive licks, at doses which actually increased rates o f o p e r a n t licking. Barrett and Weinberg [2] also investigated adjunctive drinking on a fixed-interval schedule a l t h o u g h in their e x p e r i m e n t the animals were squirrel m o n k e y s and the
o p e r a n t response was a lever press. These e x p e r i m e n t e r s f o u n d that c h l o r d i a z e p o x i d e increased adjunctive drinking, measured in this case as the a m o u n t of fluid {either w a t e r or an e t h a n o l solution) c o n s u m e d . A facilitation of adjunctive drinking after the a d m i n i s t r a t i o n o f c h l o r d i a z e p o x ide has also been r e p o r t e d by Sanger and Blackman [13] who found that a {lose of this drug e n h a n c e d the acquisition of adjunctive licking in one group o f rats while reducing levels of established licking in a second group. More recently, Bacotti and Barrett [1] have also r e p o r t e d that c h l o r d i a z e p o x i d e increases levels of adjunctive drinking in rats. A l t h o u g h there are several d i f f e r e n c e s b e t w e e n the results o b t a i n e d in these e x p e r i m e n t s it seems clear that adjunctive drinking is sensitive to the actions o f chlordiazepoxide. The presenl e x p e r i m e n t was an a t t e m p t to obtain further i n f o r m a t i o n c o n c e r n i n g the actions of similar drugs on this p a t t e r n o f behavior. The drugs used were diazepam, which, like c h l o r d i a z e p o x i d e , is a b e n z o d i a z e p i n e , and ripazcpaln ( f o r m e r l y k n o w n as p y r a z a p o n ) . The latter is a p y r a z o l o d i a z c p i n o n e , rather than a b e n z o d i a z e p i n e , but has heen s h o w n to share several o f the pharmacological and behavioral actions o f c h l o r d i a z e p o x i d e [ 12]. METIlOI)
A n ima ls F o u r female h o o d e d rats, a p p r o x i m a t e l y 150 days old at the beginning of the e x p e r i m e n t , served as tes! animals.
We are grateful to Roche Products Limited who supplied lhe diazepam and to Parke Davis and Company who provided us with ripazepam. 21.C.I. Research Fellow. 139
140
SANGER AND BLACKMAN
They Were individually h o u s e d and m a i n t a i n e d at 85% of their p r e - e x p e r i m e n t a l weights w h i c h were w i t h i n the range 1 8 5 - 2 0 0 g. Water was c o n t i n u o u s l y available in the h o m e cages.
Apparatus The a p p a r a t u s consisted of 2 s t a n d a r d o p e r a n t test c h a m b e r s (L.V.E.) enclosed in s o u n d and light p r o o f o u t e r cubicles. In each c h a m b e r the lever to the right of the food c h u t e was r e m o v e d as were the 3 s t i m u l u s lights s i t u a t e d above this lever. Pieces of steel were used to cover the resulting o p e n i n g s with the e x c e p t i o n of t h a t p r o d u c e d by the removal o f the middle s t i m u l u s light (1.5 cm in dia.). A plastic w a t e r tube was securely fixed to the o u t s i d e of each c h a m b e r so t h a t the m e t a l s p o u t was p o s i t i o n e d just b e h i n d ( a p p r o x i m a t e l y 1 - 2 ram) this opening. W h e n placed in the c h a m b e r s the rats could reach t h r o u g h the o p e n i n g s to lick the w a t e r spouts. Each s p o u t was a p p r o x i m a t e l y 5.5 cm to the right of and 8 cm higher t h a n the food c h u t e . C o n t a c t s with the s p o u t s were sensed by c o n t a c t relays w h i c h were c o n n e c t e d to the s p o u t s and the grid floors of the test c h a m b e r s . P r o g r a m m i n g of the e x p e r i m e n t and recording o f licking were achieved by m e a n s o f s t a n d a r d electromechanical equipment.
Procedure T h e rats were given 2 one hr sessions to allow t h e m to a d a p t to the test c h a m b e r s . During these sessions a few food pellets (45 rag) were placcd in the food c h u t c s and the w a t e r t u b e s were in place. A f t e r this a d a p t i o n to the c h a m b e r s , the a n i m a l s were given daily sessions d u r i n g which 6 0 45 mg food pellets were delivered regularly at I rain intervals to each animal i n d e p e n d e n t l y of its behavior. The n u m b e r of licks w h i c h o c c u r r e d after thc delivery of each pellet was recorded, as was the v o l u m e of w a t e r c o n s u m e d d u r i n g each session. At the end of each session the c h a m b e r s were checked for possible spillage b u t u n d e r n o n e o f the c o n d i t i o n s of the p r e s e n t experinaent could spillage be d e t e c t e d . When all four animals developed steady day to day drinking baselines, drug a d m i n i s t r a t i o n was begun. T h e drugs used were d i a z e p a m in doses of 0 . 1 , 0 . 3 , 1.0, 3.0 and 5.6 m g / k g and r i p a z e p a m in doses of I. 3, 10, 30 and 56 mg/kg. B o t h drugs were injected IP as s u s p e n s i o n s in 1% T w e e n 80 in physiological saline. I n j e c t i o n s were given a p p r o x i m a t e l y 5 rain before the start of a session and al least 3 n o n d r u g days separated successive drug days, the vehicle being injected on all n o n d r u g days. A d m i n i s t r a t i o n of r i p a z e p a m p r e c e d e d t h a t of d i a z e p a m and the doses of b o t h drugs were given in a mixed order, the o r d e r being different for each animal.
Figure I p r e s e n t s dose-response curves s h o w i n g the effects of b o t h d i a z e p a m and r i p a z e p a m on levels of w a t e r intake in the 4 individual animals. V o l u m e s of w a t e r c o n s u m e d after each drug a d m i n i s t r a t i o n are s h o w n in c o m p a r i s o n with the m e a n and c o m p l e t e range of c o n t r o l values of this measure t a k e n f r o m the sessions i m m e d i a t e l v preceding drug sessions (i.e., 10 c o n t r o l sessions for each rat). The highest dose of b o t h drugs reduced levels of w a t e r intake in 3 of the 4 rats while lower doses e i t h e r had no effect on or increased these levels. At least one dose of d i a z e p a m p r o d u c e d a small increase in w a t e r intake in all but o n e IR 1) o f the animals while r i p a z e p a m in doses of either 3.0 or 10 mg/kg p r o d u c e d larger increases in all 4 rat s. Dose-response curves showing the effects of the 2 drugs on a m o u n t of licking are p r e s e n t e d in Fig. 2. A l t h o u g h these curves a p p e a r generally similar to those p r e s e n t e d in Fig. I close c o m p a r i s o n of these 2 figures shows a n u m b e r of differences. T h e increases in levels of w a t e r intake p r o d u c e d by lower and i n t e r m e d i a t e doses of b o t h d i a z e p a m and r i p a z e p a m are f r e q u e n t l y not a c c o m p a n i e d by increases in levels of licking. F o r instance, ripazepam at 3.0 mg/kg, w h i c h increased levels of w a t e r intake in three animals, did not increase n u m b e r s of licks. Licking was increased to values outside the range of c o n t r o l rates only by 0.1 m g / k g of d i a z e p a m in R 2 and R 4 and by 1.0 m g / k g of ripazepam in R 2. However, these doses did not increase levels of water intake in any animal. This a p p a r e n t dissociation b e t w e e n the drug effects o n w a t e r intake and • D~azeDam
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RFSUI,TS The four rats developed c o n s i s t e n t l y high levels of adjunctive drinking. A burst of licking would typically follow i m m e d i a t e l y after c o n s u m p t i o n of each of 55 to 60 food pellets of the 60 delivered d u r i n g each session. Each animal c o n s u m c d a p p r o x i m a t e l y 1 5 25 ml of w a t e r d u r i n g each session which r e p r e s e n t e d a p p r o x i m a t e l y 5 , 0 0 0 10,000 licks per session. The effects of d i a z e p a m and ripazepam were assessed b o t h in t e r m s of the v o l u m e of w a t e r c o n s u m e d and also in tertns of the t o t a l n u m b e r of licks.
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D I A Z E P A M A N D R I P A Z E P A M I - F F E C T S ON A D J U N C T I V E D R I N K I N G • Diazepam
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FIG. 2. Dose response curves showing the effects of diazepam and ripazepam on numbers of licks in the 4 individual rats. Each point shows the number of licks during a complete session after one administration of each dose exept for the points at C which show the means and complete ranges of numbers of licks for sessions immediately preceding each drug session (i.e., 10 .sessions for each animal). on licking was also s h o w n at higher doses of b o t h drugs w h e n , on scveral occasions, lick rates were decreased to values o u t s i d e the c o n t r o l range while levels of w a t e r i n t a k e were u n a f f e c t e d . Such an cffect was seen with 3.0 m g / k g o f d i a z e p a m in R 1, R2 and R 3, and w i t h at least one dose of r i p a z e p a m with all 4 animals. I)ISCUSSION Both d i a z e p a m , a b c n z o d i a z e p i n e , and r i p a z e p a m , w h i c h has been s h o w n to have p h a r m a c o l o g i c a l actions similar to those of the b e n z o d i a z e p i n e s [12] were f o u n d to increase levels of a d j u n c t i v e d r i n k i n g in rats. This rcsult is c o n s i s t e n t with t h a t o b t a i n e d by Barrett and Weinberg 12] w h o f o u n d that levels of a d j u n c t i v e d r i n k i n g in squirrel m o n k e y s wcre increased by the a d m i n i s t r a t i o n o f c h l o r d i a z e p o x i d e . T h e fact t h a t t h e r e were several d i f f e r e n c c s in p r o c e d u r e b e t w e e n the present e x p e r i m e n t and t h a t r e p o r t e d by Barrett and Weinberg, including the species of animal, the schedule on w h i c h food was delivered and the particular b e n z o d i a z e p i n e used, suggests t h a t a n x i o l y t i c drugs m a y e n h a n c c a d j u n c t i v e d r i n k i n g u n d e r a wide range of experim e n t a l c o n d i t i o n s . An increase in levels of b o t h w a t e r intake and licking has also b e e n r e p o r t e d by Bacotti and Barrett I1] w h o a d m i n i s t e r e d c h l o r d i a z e p o x i d e to rats
141
whose f o o d - r e i n f o r c e d lever pressing was m a i n t a i n e d by a m u l t i p l e fixed-interval fixed-ratio schedule. M c K e a r n e y [ 1 1 ] , h o w e v e r , did not find t h a t c h l o r d i a z e p o x i d e increased levels o f a d j u n c t i v e licking in rats. It is possible t h a t this result m a y have b e e n related to the fact t h a t in M c K e a r n e y ' s e x p e r i m e n t licking was also the o p e r a n t response. A n o t h e r possibility, however, is t h a t the failure to observe e n h a n c e d a d j u n c t i v e d r i n k i n g was due to d r i n k i n g being m e a s u r e d o n l y in t e r m s of licks. In the present e x p e r i m e n t some d i s s o c i a t i o n was observed b e t w e e n the ways in w h i c h the t w o m e a s u r e s of adjunctive d r i n k i n g were affected by the drugs, in general, it seemed t h a t the measure of w a t e r intake was more sensitive to increases in d r i n k i n g while licking was more sensitive to decreases. These results suggest t h a t the drugs may have altered the t o p o g r a p h y o f licking, t h a t is the way in w h i c h the rats licked the w a t e r spouts. A f u r t h e r possibility, w h i c h might be m e n t i o n e d , is that the drugs increased local rates of licking to such an e x t e n t t h a t the e l e c t r o m e c h a n i c a l c o u n t e r s were u n a b l e to c o u n t every lick. a l t h o u g h it appears from the available evidence t h a t variations in rates of licking tend to be small 14]. W h a t e v e r thc reason for these dissociations of w a t e r intake and n u m b e r s of licks the p r e s e n t results indicate that e x p e r i m c n t s in w h i c h the effects o f drugs on adjunctive drinking, and indeed d r i n k i n g in o t h e r situations, are studied should measure b o t h the v o l u m e of fluid c o n s u m e d and the n u m b e r of licks. In most of the p u b l i s h e d e x p e r i m e n t s w h i c h have investigated the actions of drugs o n a d j u n c t i v e d r i n k i n g only a single measure of drinking, usually licking, has been r e p o r t e d . T h e e x p e r i m e n t described by W a y n e r et al. [181 in which the effects of d - a m p h e t a m i n e were studied provides an e x c e p t i o n to this generalization. In this e x p e r i m e n t , however, d - a m p h e t a m i n e generally had similar effects on b o t h licking and on the v o l u m e s of w a t e r c o n s u m e d , a l t h o u g h at high doses these measures were depressed to d i f f e r e n t e x t e n t s . In this c o n t e x t it is interesting to note the results o b t a i n e d by K n o w l e r and U k e n a [101. Thesc researchers studied the effects o f several drugs, including chlordiazcpoxide, o n p a t t e r n s of d e p r i v a t i o n - i n d u c e d d r i n k i n g in rats. Certain doses of c h l o r d i a z e p o x i d e were f o u n d to increase the v o l u m e s of w a t e r c o n s u m e d b u t licking was also increased by these doses. T h e results of the present e x p e r i m e n t are c o n s i s t e n t w i t h those o b t a i n e d in several previous studies [1, 2, 13] in showing t h a t drugs with clinical a n t i - a n x i e t y p r o p e r t i e s can increase lcvels of a d j u n c t i v e drinking. This action is in c o n t r a s t to those s h o w n by a n u m b e r of o t h e r classes o f drugs, including s t i m u l a n t s and agents with a n t i c h o l i n c r g i c properties, w h i c h have b e e n f o u n d to dcprcss levels of adjunctive d r i n k i n g [3, 6, 11, 14, 15, 191. It will be necessary for any t h c o r e t i c a l view of adjunctive d r i n k i n g to a c c o u n t for the sensitivity of such d r i n k i n g to the effects of d i f f e r e n t drugs. At prescnt, however, it would seem difficult /'or t h e o r i e s which view a d j u n c t i v e d r i n k i n g as the o u t c o m e o f h y p o t h e s i s e d e m o t i o n a l states such as a n x i e t y I')l or f r u s t a t i o n 1161 to satisfactorily a c c o u n t for the actions of a n x i o l y t i c drugs since such drugs might be e x p e c t e d to reduce the i n t e n s i t y of any e m o t i o n a l stale and thus not lead to increases in drinking.
REFERENCES Bacolti, A. V. and J. 1.2 Barrett. Effects of chlordiazepoxide on schedule-controlled responding and schedule-induced drinking, Pharmac. Biochem. Behav. 4: 299-304, 1976.
2. Barrett, J. E. and I:.. S. Wcinberg. Effects of chlordiazepoxide on schedule-induced water and alcohol consumption in the squirrel monkey. Psychopharmacologia 4 0 : 3 1 9 328, 1975.
142
3.
4. 5. 6.
7. 8.
9.
10.
1 I.
SANGER
Burks, C. D. and A. I-. t.isher. Anticholincrgic blockade of schedule-induced polydipsia. Phy.s'iol. Behav. 5 : 6 3 5 640, 1970. Conc, D. M. Do m a m m a l s lick at a constant rate? A critical review of the literature. Psycho/. Record. 24: 3 5 3 - 364, 1974. I.alk, J. I.. Production of polydipsia in normal rats by an intermittent food schedule. Science 1 3 3 : 1 9 5 - 196, 196 I. Falk, J. L. Studies on schedule-induced polydipsia. In: Thir.~t in the RegTdation o f Body Water, edited by M. J. Wayner. Oxford : Pergamon Press, 1964, pp. 95 - 116. Falk, J. L. Conditions producing psychogenic polydipsia in animals. Ann. N. Y. Acad. Sci. 1 5 7 : 5 6 9 593. 1969. Gilbert, R. M. Effects of ethanol on adjunctive drinking and bar pressing under various schedules of lood reinforcement. Bull. Psychon. Soc. I: 1 6 1 - 1 6 4 , 1973. King, G. D. Thc e n h a n c e m e n t of schedule-induced polydipsia by preschedule noncontingent shock. Bull. P.wchon. Sot'. 3: 46 48, 1974. Knowler, W. C. and T. I'L Ukena. The effects of chlorpromazine, pentobarbital, chlordiazcpoxide and d-amphelaminc on rates of licking in thc rat. J. Pharmacol. exp. Ther. 184: 3 8 5 - 3 9 7 , 1973. McKearneY, J. W. Effects of m e t h a m p h e t a m i n c and chlordiazepoxide on schedule-controlled and adjunclive licking in the rat. PErchol~harmacologia 311:375 384, 1973.
12.
13.
14.
15.
16.
17.
18.
19.
A N D BI_.ACKMAN
Poschel, B. P. I1., D. A. McCarthy, G. ("hen and C. R. l. nsor. Pyrazapon (CI-683): A ncw antianxiety agent. Pwchopharmavologia 35: 2 5 7 - 2 7 1 , 1974. Sanger, D. J. and D. 1'i. Blackman. The effects of chlordiazcpoxide on the development of adjunctive drinking in rats. Q. Jl exp. Psychol. 27: 499- 505, 1975. Segal, I.i. 1.. and S. A. Deadwyler. A m p h e t a m i n e differentially affects spaced bar pressing and collateral water drinking. Psychon. Sci. 1: 349- 350, 1964. Scgal, 1.i.I.., I.). L. Odcn and S. A. Deadwyler. Determinants of polydipsia: V. Effects of a m p h e t a m i n e and pentobarhital. Psychon. Sci. 3 : 3 3 34, 1965. T h o m k a , ),t. 1.. and R. A. Roscllini. I'rustration and the production of schedule-induced polydipsia. An#n. Learn. Behav. 3:3811 384, 1975. Wayner, M. J., 1. Greenberg, S. l:raley and S. l.ishcr. ]-.ffecls of A~-tetrahydrocannabinol and ethyl alcohol on adjunctive behavior and the lateral hypothalanlus. Physiol Behar. I0: 109 132, 1973. Wayner, M. J., 1. Grecnberg and J. lrowbridge, l f f e c l s o | d-amphctanfine tm schedule-induced polydipsia. Pharmac. Biochem. Behal,. I: 109 I I1, 1973. Wutlke, W. and N. K. Innis. Drug effects tJpon behavic, r induced by second-order schedules the relevance of eth~flogical analyses. In: Scheduh' l:']]'ects: Dn~gs, Drinking and Aggression, edited by R..M. Gilbert and J. D. Kcehn. "l'oront~: University of T o r o n t o P r c s s . 1972. pp. 129 147.
Effects of Diazepam and Ripazepam on Two Measures of Adjunctive Drinking in Rats' D. J. S A N G E R z AND D. E. B L A C K M A N Department ~ff"Psycholog3,, University o f Birmingham, P.O. Box 363, Birmingham, B15 2TT, England {Received 20 O c t o b e r 1975) SANGER, D. J. AND I). I'. BLACKMAN. l',ffects of diazepam and ripazepam on two measures o]ad]unctive drinking in rats. PIIARMAC. BI(X?IIEM. BtSHAV. 5(2) 139 142, 1976. Four rats were maintaincd at 85% of their pre-experimental body weights and were given daily I hr sessions during which they were each placed in a test chamber in which a 45 mg food pellet was delivered regularly every rain independently of behavior. During these sessions water spouts were available to the rats and all 4 animals developed high levels of adjunctive drinking, a burst of licking typically following the consumption of each food pellet. This behavior was found to be sensitive to the effects of diazepam and ripazepam. Small doses of both drugs increased the volume of water consumed druing a session. The number of licks was not increased to the same extent, however. Larger doses of both drugs resulted in decreased numbers of licks and decreased water intake although licking appeared on several occasions to be mort sensitive than water intake to this action of the drugs. A possible explanation of these effects is that the drugs affected lhe topography of the rats' licking at the water spouts. Whatever the mechanism inw~lvcd, however, these results suggest that in such experiments measures of both water intake and number of licks should be obtained. Diazepam
Ripazepam
Adjunctive drinking
Licking
WHEN food deprived animals receive small p o r t i o n s o f food delivered i n t e r m i t t e n t l y they have been observed to drink large q u a n t i t i e s o f water, a burst of drinking typically occurring after the c o n s u m p t i o n of each food p o r t i o n [ 5 ] . This behavior has been described as s c h e d u l e - i n d u c e d polydipsia and it has been suggested that it is one o f a class of behaviors which Falk [7] has n a m e d adjunctive. Several reports have described the e f f e c t s o f a m p h e t a mines on adjunctive drinking, w h i c h is generally a t t e n u a t e d by the a d m i n i s t r a t i o n of these drugs 16, 11, 14, 15, 1~)1. Wayner et al. [ l g ] , h o w e v e r , observed increases in adjunctive drinking after the a d m i n i s t r a t i o n o f small doses o f d - a m p h e t a m i n e to a rat with a relatively low baseline rate of drinking. Decreases in adjunctive drinking have also been r e p o r t e d after a d m i n i s t r a t i o n of p e n t o b a r b i t a l 16,151, a t r o p i n e [3] and e t h a n o l [g] and drinking has been f o u n d to be increased by certain doses o f zx~ THC [ 17]. R e c e n t l y a n u m b e r of e x p e r i m e n t s have investigated the actions of c h l o r d i a z e p o x i d e on adjunctive drinking. McKearney [11] sludied the adjunctive licking o f rats which were m a i n t a i n e d on a fixed-interval schedule o f r e i n f o r c e m e n t for which the o p e r a n t response was also licking the water tube. C h l o r d i a z e p o x i d c was f o u n d to have little effect on or even to decrease the n u m b e r o f adjunctive licks, at doses which actually increased rates o f o p e r a n t licking. Barrett and Weinberg [2] also investigated adjunctive drinking on a fixed-interval schedule a l t h o u g h in their e x p e r i m e n t the animals were squirrel m o n k e y s and the
o p e r a n t response was a lever press. These e x p e r i m e n t e r s f o u n d that c h l o r d i a z e p o x i d e increased adjunctive drinking, measured in this case as the a m o u n t of fluid {either w a t e r or an e t h a n o l solution) c o n s u m e d . A facilitation of adjunctive drinking after the a d m i n i s t r a t i o n o f c h l o r d i a z e p o x ide has also been r e p o r t e d by Sanger and Blackman [13] who found that a {lose of this drug e n h a n c e d the acquisition of adjunctive licking in one group o f rats while reducing levels of established licking in a second group. More recently, Bacotti and Barrett [1] have also r e p o r t e d that c h l o r d i a z e p o x i d e increases levels of adjunctive drinking in rats. A l t h o u g h there are several d i f f e r e n c e s b e t w e e n the results o b t a i n e d in these e x p e r i m e n t s it seems clear that adjunctive drinking is sensitive to the actions o f chlordiazepoxide. The presenl e x p e r i m e n t was an a t t e m p t to obtain further i n f o r m a t i o n c o n c e r n i n g the actions of similar drugs on this p a t t e r n o f behavior. The drugs used were diazepam, which, like c h l o r d i a z e p o x i d e , is a b e n z o d i a z e p i n e , and ripazcpaln ( f o r m e r l y k n o w n as p y r a z a p o n ) . The latter is a p y r a z o l o d i a z c p i n o n e , rather than a b e n z o d i a z e p i n e , but has heen s h o w n to share several o f the pharmacological and behavioral actions o f c h l o r d i a z e p o x i d e [ 12]. METIlOI)
A n ima ls F o u r female h o o d e d rats, a p p r o x i m a t e l y 150 days old at the beginning of the e x p e r i m e n t , served as tes! animals.
We are grateful to Roche Products Limited who supplied lhe diazepam and to Parke Davis and Company who provided us with ripazepam. 21.C.I. Research Fellow. 139
140
SANGER AND BLACKMAN
They Were individually h o u s e d and m a i n t a i n e d at 85% of their p r e - e x p e r i m e n t a l weights w h i c h were w i t h i n the range 1 8 5 - 2 0 0 g. Water was c o n t i n u o u s l y available in the h o m e cages.
Apparatus The a p p a r a t u s consisted of 2 s t a n d a r d o p e r a n t test c h a m b e r s (L.V.E.) enclosed in s o u n d and light p r o o f o u t e r cubicles. In each c h a m b e r the lever to the right of the food c h u t e was r e m o v e d as were the 3 s t i m u l u s lights s i t u a t e d above this lever. Pieces of steel were used to cover the resulting o p e n i n g s with the e x c e p t i o n of t h a t p r o d u c e d by the removal o f the middle s t i m u l u s light (1.5 cm in dia.). A plastic w a t e r tube was securely fixed to the o u t s i d e of each c h a m b e r so t h a t the m e t a l s p o u t was p o s i t i o n e d just b e h i n d ( a p p r o x i m a t e l y 1 - 2 ram) this opening. W h e n placed in the c h a m b e r s the rats could reach t h r o u g h the o p e n i n g s to lick the w a t e r spouts. Each s p o u t was a p p r o x i m a t e l y 5.5 cm to the right of and 8 cm higher t h a n the food c h u t e . C o n t a c t s with the s p o u t s were sensed by c o n t a c t relays w h i c h were c o n n e c t e d to the s p o u t s and the grid floors of the test c h a m b e r s . P r o g r a m m i n g of the e x p e r i m e n t and recording o f licking were achieved by m e a n s o f s t a n d a r d electromechanical equipment.
Procedure T h e rats were given 2 one hr sessions to allow t h e m to a d a p t to the test c h a m b e r s . During these sessions a few food pellets (45 rag) were placcd in the food c h u t c s and the w a t e r t u b e s were in place. A f t e r this a d a p t i o n to the c h a m b e r s , the a n i m a l s were given daily sessions d u r i n g which 6 0 45 mg food pellets were delivered regularly at I rain intervals to each animal i n d e p e n d e n t l y of its behavior. The n u m b e r of licks w h i c h o c c u r r e d after thc delivery of each pellet was recorded, as was the v o l u m e of w a t e r c o n s u m e d d u r i n g each session. At the end of each session the c h a m b e r s were checked for possible spillage b u t u n d e r n o n e o f the c o n d i t i o n s of the p r e s e n t experinaent could spillage be d e t e c t e d . When all four animals developed steady day to day drinking baselines, drug a d m i n i s t r a t i o n was begun. T h e drugs used were d i a z e p a m in doses of 0 . 1 , 0 . 3 , 1.0, 3.0 and 5.6 m g / k g and r i p a z e p a m in doses of I. 3, 10, 30 and 56 mg/kg. B o t h drugs were injected IP as s u s p e n s i o n s in 1% T w e e n 80 in physiological saline. I n j e c t i o n s were given a p p r o x i m a t e l y 5 rain before the start of a session and al least 3 n o n d r u g days separated successive drug days, the vehicle being injected on all n o n d r u g days. A d m i n i s t r a t i o n of r i p a z e p a m p r e c e d e d t h a t of d i a z e p a m and the doses of b o t h drugs were given in a mixed order, the o r d e r being different for each animal.
Figure I p r e s e n t s dose-response curves s h o w i n g the effects of b o t h d i a z e p a m and r i p a z e p a m on levels of w a t e r intake in the 4 individual animals. V o l u m e s of w a t e r c o n s u m e d after each drug a d m i n i s t r a t i o n are s h o w n in c o m p a r i s o n with the m e a n and c o m p l e t e range of c o n t r o l values of this measure t a k e n f r o m the sessions i m m e d i a t e l v preceding drug sessions (i.e., 10 c o n t r o l sessions for each rat). The highest dose of b o t h drugs reduced levels of w a t e r intake in 3 of the 4 rats while lower doses e i t h e r had no effect on or increased these levels. At least one dose of d i a z e p a m p r o d u c e d a small increase in w a t e r intake in all but o n e IR 1) o f the animals while r i p a z e p a m in doses of either 3.0 or 10 mg/kg p r o d u c e d larger increases in all 4 rat s. Dose-response curves showing the effects of the 2 drugs on a m o u n t of licking are p r e s e n t e d in Fig. 2. A l t h o u g h these curves a p p e a r generally similar to those p r e s e n t e d in Fig. I close c o m p a r i s o n of these 2 figures shows a n u m b e r of differences. T h e increases in levels of w a t e r intake p r o d u c e d by lower and i n t e r m e d i a t e doses of b o t h d i a z e p a m and r i p a z e p a m are f r e q u e n t l y not a c c o m p a n i e d by increases in levels of licking. F o r instance, ripazepam at 3.0 mg/kg, w h i c h increased levels of w a t e r intake in three animals, did not increase n u m b e r s of licks. Licking was increased to values outside the range of c o n t r o l rates only by 0.1 m g / k g of d i a z e p a m in R 2 and R 4 and by 1.0 m g / k g of ripazepam in R 2. However, these doses did not increase levels of water intake in any animal. This a p p a r e n t dissociation b e t w e e n the drug effects o n w a t e r intake and • D~azeDam
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RFSUI,TS The four rats developed c o n s i s t e n t l y high levels of adjunctive drinking. A burst of licking would typically follow i m m e d i a t e l y after c o n s u m p t i o n of each of 55 to 60 food pellets of the 60 delivered d u r i n g each session. Each animal c o n s u m c d a p p r o x i m a t e l y 1 5 25 ml of w a t e r d u r i n g each session which r e p r e s e n t e d a p p r o x i m a t e l y 5 , 0 0 0 10,000 licks per session. The effects of d i a z e p a m and ripazepam were assessed b o t h in t e r m s of the v o l u m e of w a t e r c o n s u m e d and also in tertns of the t o t a l n u m b e r of licks.
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D I A Z E P A M A N D R I P A Z E P A M I - F F E C T S ON A D J U N C T I V E D R I N K I N G • Diazepam
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FIG. 2. Dose response curves showing the effects of diazepam and ripazepam on numbers of licks in the 4 individual rats. Each point shows the number of licks during a complete session after one administration of each dose exept for the points at C which show the means and complete ranges of numbers of licks for sessions immediately preceding each drug session (i.e., 10 .sessions for each animal). on licking was also s h o w n at higher doses of b o t h drugs w h e n , on scveral occasions, lick rates were decreased to values o u t s i d e the c o n t r o l range while levels of w a t e r i n t a k e were u n a f f e c t e d . Such an cffect was seen with 3.0 m g / k g o f d i a z e p a m in R 1, R2 and R 3, and w i t h at least one dose of r i p a z e p a m with all 4 animals. I)ISCUSSION Both d i a z e p a m , a b c n z o d i a z e p i n e , and r i p a z e p a m , w h i c h has been s h o w n to have p h a r m a c o l o g i c a l actions similar to those of the b e n z o d i a z e p i n e s [12] were f o u n d to increase levels of a d j u n c t i v e d r i n k i n g in rats. This rcsult is c o n s i s t e n t with t h a t o b t a i n e d by Barrett and Weinberg 12] w h o f o u n d that levels of a d j u n c t i v e d r i n k i n g in squirrel m o n k e y s wcre increased by the a d m i n i s t r a t i o n o f c h l o r d i a z e p o x i d e . T h e fact t h a t t h e r e were several d i f f e r e n c c s in p r o c e d u r e b e t w e e n the present e x p e r i m e n t and t h a t r e p o r t e d by Barrett and Weinberg, including the species of animal, the schedule on w h i c h food was delivered and the particular b e n z o d i a z e p i n e used, suggests t h a t a n x i o l y t i c drugs m a y e n h a n c c a d j u n c t i v e d r i n k i n g u n d e r a wide range of experim e n t a l c o n d i t i o n s . An increase in levels of b o t h w a t e r intake and licking has also b e e n r e p o r t e d by Bacotti and Barrett I1] w h o a d m i n i s t e r e d c h l o r d i a z e p o x i d e to rats
141
whose f o o d - r e i n f o r c e d lever pressing was m a i n t a i n e d by a m u l t i p l e fixed-interval fixed-ratio schedule. M c K e a r n e y [ 1 1 ] , h o w e v e r , did not find t h a t c h l o r d i a z e p o x i d e increased levels o f a d j u n c t i v e licking in rats. It is possible t h a t this result m a y have b e e n related to the fact t h a t in M c K e a r n e y ' s e x p e r i m e n t licking was also the o p e r a n t response. A n o t h e r possibility, however, is t h a t the failure to observe e n h a n c e d a d j u n c t i v e d r i n k i n g was due to d r i n k i n g being m e a s u r e d o n l y in t e r m s of licks. In the present e x p e r i m e n t some d i s s o c i a t i o n was observed b e t w e e n the ways in w h i c h the t w o m e a s u r e s of adjunctive d r i n k i n g were affected by the drugs, in general, it seemed t h a t the measure of w a t e r intake was more sensitive to increases in d r i n k i n g while licking was more sensitive to decreases. These results suggest t h a t the drugs may have altered the t o p o g r a p h y o f licking, t h a t is the way in w h i c h the rats licked the w a t e r spouts. A f u r t h e r possibility, w h i c h might be m e n t i o n e d , is that the drugs increased local rates of licking to such an e x t e n t t h a t the e l e c t r o m e c h a n i c a l c o u n t e r s were u n a b l e to c o u n t every lick. a l t h o u g h it appears from the available evidence t h a t variations in rates of licking tend to be small 14]. W h a t e v e r thc reason for these dissociations of w a t e r intake and n u m b e r s of licks the p r e s e n t results indicate that e x p e r i m c n t s in w h i c h the effects o f drugs on adjunctive drinking, and indeed d r i n k i n g in o t h e r situations, are studied should measure b o t h the v o l u m e of fluid c o n s u m e d and the n u m b e r of licks. In most of the p u b l i s h e d e x p e r i m e n t s w h i c h have investigated the actions of drugs o n a d j u n c t i v e d r i n k i n g only a single measure of drinking, usually licking, has been r e p o r t e d . T h e e x p e r i m e n t described by W a y n e r et al. [181 in which the effects of d - a m p h e t a m i n e were studied provides an e x c e p t i o n to this generalization. In this e x p e r i m e n t , however, d - a m p h e t a m i n e generally had similar effects on b o t h licking and on the v o l u m e s of w a t e r c o n s u m e d , a l t h o u g h at high doses these measures were depressed to d i f f e r e n t e x t e n t s . In this c o n t e x t it is interesting to note the results o b t a i n e d by K n o w l e r and U k e n a [101. Thesc researchers studied the effects o f several drugs, including chlordiazcpoxide, o n p a t t e r n s of d e p r i v a t i o n - i n d u c e d d r i n k i n g in rats. Certain doses of c h l o r d i a z e p o x i d e were f o u n d to increase the v o l u m e s of w a t e r c o n s u m e d b u t licking was also increased by these doses. T h e results of the present e x p e r i m e n t are c o n s i s t e n t w i t h those o b t a i n e d in several previous studies [1, 2, 13] in showing t h a t drugs with clinical a n t i - a n x i e t y p r o p e r t i e s can increase lcvels of a d j u n c t i v e drinking. This action is in c o n t r a s t to those s h o w n by a n u m b e r of o t h e r classes o f drugs, including s t i m u l a n t s and agents with a n t i c h o l i n c r g i c properties, w h i c h have b e e n f o u n d to dcprcss levels of adjunctive d r i n k i n g [3, 6, 11, 14, 15, 191. It will be necessary for any t h c o r e t i c a l view of adjunctive d r i n k i n g to a c c o u n t for the sensitivity of such d r i n k i n g to the effects of d i f f e r e n t drugs. At prescnt, however, it would seem difficult /'or t h e o r i e s which view a d j u n c t i v e d r i n k i n g as the o u t c o m e o f h y p o t h e s i s e d e m o t i o n a l states such as a n x i e t y I')l or f r u s t a t i o n 1161 to satisfactorily a c c o u n t for the actions of a n x i o l y t i c drugs since such drugs might be e x p e c t e d to reduce the i n t e n s i t y of any e m o t i o n a l stale and thus not lead to increases in drinking.
REFERENCES Bacolti, A. V. and J. 1.2 Barrett. Effects of chlordiazepoxide on schedule-controlled responding and schedule-induced drinking, Pharmac. Biochem. Behav. 4: 299-304, 1976.
2. Barrett, J. E. and I:.. S. Wcinberg. Effects of chlordiazepoxide on schedule-induced water and alcohol consumption in the squirrel monkey. Psychopharmacologia 4 0 : 3 1 9 328, 1975.
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4. 5. 6.
7. 8.
9.
10.
1 I.
SANGER
Burks, C. D. and A. I-. t.isher. Anticholincrgic blockade of schedule-induced polydipsia. Phy.s'iol. Behav. 5 : 6 3 5 640, 1970. Conc, D. M. Do m a m m a l s lick at a constant rate? A critical review of the literature. Psycho/. Record. 24: 3 5 3 - 364, 1974. I.alk, J. I.. Production of polydipsia in normal rats by an intermittent food schedule. Science 1 3 3 : 1 9 5 - 196, 196 I. Falk, J. L. Studies on schedule-induced polydipsia. In: Thir.~t in the RegTdation o f Body Water, edited by M. J. Wayner. Oxford : Pergamon Press, 1964, pp. 95 - 116. Falk, J. L. Conditions producing psychogenic polydipsia in animals. Ann. N. Y. Acad. Sci. 1 5 7 : 5 6 9 593. 1969. Gilbert, R. M. Effects of ethanol on adjunctive drinking and bar pressing under various schedules of lood reinforcement. Bull. Psychon. Soc. I: 1 6 1 - 1 6 4 , 1973. King, G. D. Thc e n h a n c e m e n t of schedule-induced polydipsia by preschedule noncontingent shock. Bull. P.wchon. Sot'. 3: 46 48, 1974. Knowler, W. C. and T. I'L Ukena. The effects of chlorpromazine, pentobarbital, chlordiazcpoxide and d-amphelaminc on rates of licking in thc rat. J. Pharmacol. exp. Ther. 184: 3 8 5 - 3 9 7 , 1973. McKearneY, J. W. Effects of m e t h a m p h e t a m i n c and chlordiazepoxide on schedule-controlled and adjunclive licking in the rat. PErchol~harmacologia 311:375 384, 1973.
12.
13.
14.
15.
16.
17.
18.
19.
A N D BI_.ACKMAN
Poschel, B. P. I1., D. A. McCarthy, G. ("hen and C. R. l. nsor. Pyrazapon (CI-683): A ncw antianxiety agent. Pwchopharmavologia 35: 2 5 7 - 2 7 1 , 1974. Sanger, D. J. and D. 1'i. Blackman. The effects of chlordiazcpoxide on the development of adjunctive drinking in rats. Q. Jl exp. Psychol. 27: 499- 505, 1975. Segal, I.i. 1.. and S. A. Deadwyler. A m p h e t a m i n e differentially affects spaced bar pressing and collateral water drinking. Psychon. Sci. 1: 349- 350, 1964. Scgal, 1.i.I.., I.). L. Odcn and S. A. Deadwyler. Determinants of polydipsia: V. Effects of a m p h e t a m i n e and pentobarhital. Psychon. Sci. 3 : 3 3 34, 1965. T h o m k a , ),t. 1.. and R. A. Roscllini. I'rustration and the production of schedule-induced polydipsia. An#n. Learn. Behav. 3:3811 384, 1975. Wayner, M. J., 1. Greenberg, S. l:raley and S. l.ishcr. ]-.ffecls of A~-tetrahydrocannabinol and ethyl alcohol on adjunctive behavior and the lateral hypothalanlus. Physiol Behar. I0: 109 132, 1973. Wayner, M. J., 1. Grecnberg and J. lrowbridge, l f f e c l s o | d-amphctanfine tm schedule-induced polydipsia. Pharmac. Biochem. Behal,. I: 109 I I1, 1973. Wutlke, W. and N. K. Innis. Drug effects tJpon behavic, r induced by second-order schedules the relevance of eth~flogical analyses. In: Scheduh' l:']]'ects: Dn~gs, Drinking and Aggression, edited by R..M. Gilbert and J. D. Kcehn. "l'oront~: University of T o r o n t o P r c s s . 1972. pp. 129 147.