Failure of 2-deoxy-D-glucose to stimulate feeding in deermice

Physiology&Behavior, Vol. 34, pp. 155-157. Copyright©Pergamon Press Ltd., 1985. Printed in the U.S.A.

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Failure of 2-Deoxy-D-Glucose to Stimulate Feeding in Deermice NEIL ROWLAND,

LANA WATKINS

AND JANIS CARLTON

Department o f Psychology and Center for Neurobiological Sciences, University o f Florida GainesviUe, FL 32611 R e c e i v e d 17 J a n u a r y 1984 ROWLAND, N., L. WATKINS AND J. CARLTON. Failure of 2-deoxy-D-glucose to stimulate feeding in deermice. PHYSIOL BEHAV 34(1) 155-157, 1985.--Deermice (Peromyscus maniculatus) did not increase their food intake above baseline following treatment with 2-deoxy-D-glucose (2DG, 500 or 1000 mg/kg). They did. eat more following food deprivation or treatment with insulin at a high dose (100 U/kg). House mice (Mus musculus) showed hyperphagia to 2DG, low dose of insulin (5 U/kg) and deprivation. Mice: Peromyscus maniculatus, Mus musculus Glucoprivation

2-Deoxy-D-glucose

Insulin

Food deprivation

bred) and weighed 30-35 g at the time of these experiments. All were housed individually in stainless steel mice cages (18× 10× 12 cm) with Purina chow pellets (No. 5001) and tap water available at all times. All cages w~re also furnished with a plastic Petri dish lid to afford the animals the opportunity of not sleeping on the metal surface. Room temperature was 22-+2°C. and lights were on 0800-2000 hr. Animals were used repeatedly, at 4-8 day intervals, with 6-9 per treatment group.

G L U C O P R I V A T I O N has been considered a component of normal feeding behavior, and is most usually produced in the laboratory by administration of insulin or of glucose antimetabolites such as 2-deoxy-D-glucose (2DG) [6]. Most common laboratory animals reliably increase their food intake soon after administration of either agent at appropriate doses (e.g., [6, 8, 9, 12, 16]). It was thus anomalous to find that Syrian hamsters (Mesocricetus auratus) and gerbils (Meriones unguiculatus) failed to increase food intake to glucose antimetabolites (e.g., [4, 10, 11, 14]), but under some conditions did show hyperphagia after insulin [5,10]. Because glucoprivic feeding, and its abolition with drugs and lesions, has had a major influence on our present understanding of the physiological bases o f feeding, it is necessary to more closely evaluate failures to show hyperphagia in certain species. One question concerns to generality of such findings. The present study extends these previous observations to two more muroid rodents, namely deermice (Peromyscus maniculatus) and common or house mice (Mus musculus). The former are cricetine rodents, of the same subfamily as hamsters. The latter were used primarily as a same-sized control species; they have been used extensively in physiological investigation and were, in fact, the subjects of the first report of 2DG-evoked hyperphagia [8].

Feeding Tests For food deprivation studies, food was withheld for 24 or 42 hr, and the intake of chow pellets measured in the first hr of refeeding. This intake was compared with the 1 hr intake at the same time of the day prior to deprivation. Glucoprivic feeding tests were performed in ad lib fed animals. Saline, insulin (Lilly; 5 or 100 U/kg, SC) or 2DG (Sigma; 500 or 1000 mg/kg,IP) were injected in a volume of 10 ml/kg, and food intake recorded every hour for 2--4 hr. These high doses of the agents have proven suitable and necessary for other studies with small rodents [ 11,14]. Feeding tests were conducted in the middle part of the day and in all cases intakes were recorded to the nearest 0.01 g, Spontaneous food intake was also measured during the 12 hr light and 12 hr dark periods of one 24 hr cycle.

METHOD

Physiological Measures

Animals and Housing

Following

Adult (3-6 months) male Peromyscus maniculatus, weighing 16-22 g, were obtained from the colony maintained in this department by Dr. D. A. Dewsbury. Male house mice were purchased from Charles River Laboratories (CD-1 out-

completion

of

the

behavioral

studies,

Peromyscus received either 2DG (1000 mg/kg) or saline and a blood sample was taken by capillary tube from the retroorbital sinus 1 hr later at 1100 hr. Plasma glucose was determined using a YSI 23A analyzer.

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156

R O W L A N D , W A T K I N S A N D CARLTON TABLE 1 C U M U L A T I V E C H O W I N T A K E F O L L O W I N G S A L I N E O R I N S U L I N I N J E C T I O N S IN TWO SPECIES OF MUROID RODENT

Species Treatment

Time After Treatment 1 hr

2 hr

3 hr

Peromyscus Maniculatus Saline Insulin (5 u/kg) Insulin (100 u/kg)

0.09 _+ 0.03 0.15 +_ 0.05 0.30 + 0.03**

0.22 +_ 0.05 0.28 +_ 0.07 0.54 +_ 0.075

0.42 _+ 0.08 0.36 +_ 0.11 0.73 _+ 0.07*

Mus Musculus Saline Insulin (5 u/kg)

n.d. 0.71 _+ 0.077

0.31 _+ 0.10 0.97 _+ 0.065

n.d. n.d.

Shown are M _+ SE for groups of 6--9. n.d.=not determined. *p <0.05, Sp<0.01 greater than corresponding intake after saline. tp<0.01 greater than 2 hr intake after saline.

Statistics

Peromyllcut Manicuimtuo 1.6,

The data were analyzed by A N O V A programs (SAS) with repeated measures and post-hoc Newman-Keuls procedure, as appropriate, or by t-tests.

1.4-

RESULTS

1.0-

The results from the 2DG and deprivation experiments are shown in Fig. 1. Both doses of 2DG produced large increases in food intake of Mus, but evoked no hyperphagia in Peromyscus (significant species × time interaction F(1,45)=20.3, p<0.01 (500 mg/kg); F(1,42)=21.4, p<0.01 (1000 mg/kg)). At the lower dose, no obvious hypoactivity was evident in either species (some Peromyscus appeared abnormally active), but the generally lower intakes after the higher dose are suggestive of mild debilitation. Plasma glucose levels in Peromyscus (N=6) were 100---13 mg/dl after saline and 181 ---18 mg/dl 1 hr after 2DG (1000 mg/kg, p < 0.05, t-test). Both species increased their food intake after 24 to 42 hr deprivation, relative to 0 hr deprivation (Mus: F(2,12) = 36.6, p<0.001; 42 hr>24 h r > 0 hr. Peromyscus: F(2,17)=36.6, p <0.01; 42 hr>24 h r > 0 hr). The intakes were approximately tripled in the 42 hr vs. 0 hr conditions for both species. The results from the insulin experiments are shown in Table 1. The lower dose (5 U/kg) produced clear hyperphagia in Mus (/9<0.01, t-test). Insulin also stimulated feeding in Perornyscus (F(2,63)=18.9, p<0.01 treatment effect; no treatment × time interaction). The 5 U/kg dose was apparently ineffective, while 100 U/kg stimulated feeding in all but one Peromyscus, and that animal died after 2 hr in apparent hypoglycemic shock. In the 24 hr spontaneous feeding study. Peromyscus ate 4.37___0.44 g/24 hr, of which 1.97 g (46+_-7%) was during the day and 2.40 g (54%) was nocturnal. Mus ate 6.32---0.46 g/24 hr, of which 43% was diurnal and 57% nocturnal. None of these day/night differences were significant.

.6-

DISCUSSION

The major finding is that deermice did not increase their food intake after 2DG hut did so after food deprivation (see also [7]). In this regard they resemble gerbils [11]. Syrian hamsters do not increase meal size to 2DG or deprivation

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FIG. 1. Cumulative intakes of laboratory chow by deermice (top panels) and house mice (bottom panels) following treatment with saline (S) or 2DG (500 mg/kg, left panels; 1000 mg/kg, middle panels). The 1 hr food intake following 0, 24 and 42 hr food deprivation is shown in the right panels. *p<0.05, **p<0.01 different from saline or 0 condition.

[11,13]. Gerbils and deermice do show hyperphagia after truly enormous doses of insulin. In hamsters, food intake stimulated by insulin may be a result of increased gastric emptying [5], and this may well be the case in Peromyscus. We note, however, that insulin is also a poor stimulant of lipogenesis in hamsters [15].

GLUCOPRIVIC F E E D I N G IN DEERMICE

157

We have not directly determined the spontaneous meal size or patterns of Peromyscus. However, combining all 54 of the individual hourly intakes following saline revealed the following statistics: less than 0.05 g-14 times (26%), 0.05 to 0.15 g-I 1 times (20%), and greater than 0.15 g-29 times (54%). The group mean hourly intakes in the various experiments ranged from 0.12-0.19 g. Thus, because most of the intakes exceeded 0.15 g, and most of the animals ate in every hour, it appears that the normal intermeal interval is about 1 hr and the mean meal size is about 0.15 g. Extrapolation would yield an intake of 1.8 g during the 12 hr day, in excellent agreement with the 1.97 g that we observed in the 12 hr daytime measurement. Further, Peromyscus did not exhibit a significant nycthemeral rhythm in food intake, and the same seems to be true of Mus. Both species are, however, active throughout the night [3] and a purely observational study reported more frequent feeding at night than by day [1]. Hamsters take regular meals of relatively inflexible size [13], and we have suggested that a clearance of food from the forestomach may normally control meal frequency. When

gastric clearance is stimulated by insulin, their meal frequency increases [5]. It is noteworthy that the stomach morphology ([2] and unpublished observations) and regular feeding patterns of Peromyscus and Mesocricetus are similar. The failure of 2DG to stimulate feeding, despite a clear metabolic effect (hyperglycemia) suggests this feeding stimulus is quite distinct at the neurophysiological level from that engaged by insulin. Such a suggestion has been made before by several investigators using rats (e.g., [16]), but the point is particularly clear in these comparative studies. The fact that Mus eats to both 2DG and insulin suggests that neither small body size nor natural diet (both eat seeds) can account for the failures in Peromyscus.

ACKNOWLEDGEMENTS Supported by grant BNS 8216528 from the National Science Foundation. We thank Dr. D. A. Dewsbury for donating the deermice from his colony, and for helpful comparative advice.

REFERENCES 1 Baumgardner, D. J., S. E. Ward and D. A. Dewsbury. Diurnal patterning of eight activities in 14 species of muroid rodents. Anim Learn Behav 8: 322-330, 1980. 2. Carleton, M. D. A Survey of Gross Stomach Morphology in New World Cricetinae (Rodentia, Muroidea), with Comments on Functional Interpretations.Miscellaneous Publication, Museum of Zoology, University of Michigan, No. 146, June 14, 1973. 3. Dewsbury, D. A. Wheel-running behavior in 12 species of muroid rodents. Behav Proc 5: 271-280, 1980. 4. DiBattista, D. Effects of 5-thioglucose on feeding and glycemia in the hamster. Physiol Behav 29: 803-806, 1982. 5. DiBattista, D. Food consumption, plasma glucose and stomach-emptying in insulin-injected hamsters. Physiol Behav in press. 33: 13-20, 1984. 6. Epstein, A. N., S. Nicolaldis and R. R. Miselis. The glucoprivic control of food intake and the glucostatic theory of feeding behaviour. In: Neural Integration of Physiological Mechanisms and Behaviour, edited by G. J. Mogenson and F. R. Calaresu. Toronto: Toronto University Press, 1975. 7. Jaeger, M. M. Feeding pattern in Peromyscus maniculatus: The response to periodic food deprivation. Physiol Behav 28: 83-88, 1982. 8. Likuski, H. J., A. F. Debons and R. J. Cloutier. Inhibition of gold thiogiucose induced hypothalamic obesity by glucose analogues. Am J Physiol 212: 669-676, 1967.

9. Novin, D., D. A. VanderWeele and M. Rezek. Infusion of 2-deoxy-D-glucose into the hepatic-portal system causes eating: evidence for peripheral ghicoreceptors. Science 181: 858-860, 1973. 10. Ritter, R. C. and O. K. Balch. Feeding in response to insulinbut not to 2-deoxy-D-glucose in the hamster. Am J Physiol 234: E20-E24, 1978. 11. Rowland, N. Effects of insulin and 2-deoxy-D-glucose on feeding in hamsters and gerbils. Physiol Behav 21: 291-294, 1978. 12. Rowland, N. Glucoregulatory feeding in cats. PhysiolBehav 21: 901-903, 1981. 13. Rowland, N. Failure of deprived hamsters to increase their food intake: some behavioral and physiological determinants. J Comp Physiol Psychol 96: 591--603, 1982. 14. Rowland, N. Physiological and behavioral responses to glucoprivation in the golden hamster. Physiol Behav 30: 743-747, 1983. 15. Rowland, N. Metabofic fuel homeostasis in golden hamsters: effects of fasting, refeeding, glucose and insulin. Am J Physiol, 247: R57-R62, 1984. 16. Stricker, E. M. and N. Rowland. Hepatic versus central origin of stimulus for feeding induced by 2-deoxy-D-glucose in rats. J Comp Physiol Psychol 92: 126-132, 1978.