Physiology & Behavior, Vol. 19, pp. 341-343. Pergamon Press and Brain Research Publ., 1977. Printed in the U.S.A.

BRIEF COMMUNICATION

Effects of E lec troconvuls ive S h o c k

on F o o d and Water Intake in the Rat 1

M I C H A E L J. P R E W E T T AND J O E L S. M I L N E R

Department o f Psychology, Western Carolina University, Cullowhee, NC 28723

(Received 29 Oc tober 1976)

PREWETT, M. J. AND J. S. MILNER. Effects of electroconvulsive shock on food and water intake in the rat. PHYSIOL. BEHAV. 19(2) 341-343, 1977. - - Forty-two male rats were habituated to laboratory conditions for four weeks under constant light conditions. Food and water intakes were recorded daily. Following the habituation period half of the animals were given electroconvulsive shock (ECS) and half Sham-ECS (SECS). ECS treatments produced significant decrements in both food and water intakes which returned to baseline levels after three days.

ECS Food intake Water intake

THE E F F E C T S of e lectroconvuls ive shock (ECS) on responses re inforced by food and water have been studied [2, 7, 10, 11, 12, 13]. Investigators report that ECS produces retrograde amnesia (RA) for food and water reinforced responses. In contrast , Chorover [3] suggests that " . . . many alleged examples of RA (part icularly those produced by ECS) could be accounted for more simply on grounds o ther than m e m o r y in te r fe rence ." For example, it is no t clear what effects ECS has on the intake of food and water independen t o f possible effects on learning and memory .

Adams, Hobli t and Sutker [ 1] repor t that acetylchol in- esterase (ACHE), a cholinergic antagonist , increases its act ivi ty fol lowing ECS and then returns to pre-ECS baseline over a three day period. Since ECS increases AChE activi ty [ 1 ], and blockage o f cholinergic act ivi ty has been shown to decrease water intake in the labora tory rat [4, 5, 6, 8, 9] , ECS might be expec ted to decrease water intake. If the drive level for water is altered by ECS, then this phenomena would have to be considered whenever water is employed as a reward in the study of ECS effects on learning and memory . The present s tudy investigated the effects of ECS on both food and water in take in the rat.

METHOD

Animals

For ty - two naive male Sprague-Dawley albino rats were employed. All animals arrived in the labora tory at 70 days of age and were housed individually in stainless steel cages measuring 40 × 24 × 19 cm under constant light

condit ions. Throughout the exper iment , rats were maintain- ed on an ad lib food and water schedule.

Apparatus

A Grason-Stadler shocker was used to deliver ECS which consisted o f a 30 m A constant current of 0.5 sec dura t ion delivered via saline-soaked gauze-covered ear clips. SECS consisted of a t t achment of the saline-soaked gauze-covered ear clips for five sec wi thou t delivery of shock. During the study, all subjects were presented powdered Purina Labora- tory Chow in standard Wahmann food cups and distilled water in 100 ml graduated glass drinking cylinders. Food measures were made to the nearest tenth of a gram and water measures were taken to the nearest milliliter.

Procedure

Animals were al lowed to habi tuate to the labora tory facilities for at least 4 weeks prior to ECS or SECS t reatment . During the habi tua t ion period, food and water intakes were recorded at 24-hr intervals. At the end of the habi tuat ion period, half of the animals were assigned randomly to the ECS and half to the SECS condi t ion. One ECS or one SECS was administered immedia te ly fol lowing recording of food and water intakes on the last day of the habi tuat ion period. After ECS or SECS t rea tment , measure- ments of food and water intakes were taken at 24-hr intervals for 5 days.

RESULTS

Mean daily food and water intakes across the 5 pre-ECS

This research was supported, in part, by a grant from the Western Carolina University Grants-In-Aid program.

341

342 PREWETT AND MILNER

and SECS days and the 5 post-ECS and SECS days are shown in Figs. 1 and 2, respectively. The Wi lcoxon matched-pa i r s s igned-ranks tes t [14] was e m p l o y e d to evaluate stat ist ical s ignificance be t w een the pre- and post- t r e a t m e n t days. For food in take , ECS p roduced a signifi- cant (t = 34.5. N = 21, p < 0 . 0 1 ) i n h i b i t o r y effect , while SECS did no t p roduce a s ignif icant e f fec t ( t = 79.5, N = 21, p > 0 . 0 5 ) . For wate r in take , ECS p roduced a s ignif icant (t = 6, N = 20, p~ .0 .001) depress ion effect , whereas SECS did not p roduce a s ignif icant effect (t = 76.5, N = 18, p > 0 . 0 5 ) .

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I.'IG. 1. Mean daily food intake across pre and posttreatment days for SECS and ECS group.

DISCUSSION

Analysis of the data p resen ted in Figs. 1 and 2 indica tes tha t ECS t r e a t m e n t p roduces a s ignif icant decrease in b o t h food and wate r in takes . The suppress ion of d r ink ing is suppor t ed by repor ted b iochemica l changes which occur fol lowing ECS. Adams, et al. [1] have found tha t AChE act ivi ty increases immed ia t e ly fo l lowing ECS t r e a t m e n t and an increase in chol inergic b lockage act ivi ty is k n o w n to decrease wate r in take [4, 5, 6, 8, 9 ] . Fur the r , it is in te res t ing to no te tha t Adams, et al. [1] found three days were required for AChE act ivi ty to r e tu rn to basel ine levels. Inspec t ion of Fig. 2 reveals tha t wate r in take r e tu rned to normal levels a f te r three days.

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FIG. 2. Mean daily water intake across pre and posttreatment days for SECS and ECS group.

Food in take decreased app rox ima te ly 15% and wate r in take decreased a p p r o x i m a t e l y 26% fol lowing ECS. The pa t t e rn of recovery for food in take was essent ial ly the same as t ha t for wa te r in take. Inspec t ion of Fig. 1 indica tes t h a t food in take r e tu rned to baseline levels a f te r th ree days. Since it has been repor ted t ha t food in take is regulated by the adrenergic sys tem [5, 6, 8 ] , it may be specula ted tha t the d e c r e m e n t in food in take is due to ECS effects on one or more o f the adrenergic chemicals . However , changes in food and wate r in take may no t be a direct consequence of ECS p roduced b iochemica l changes in feeding and dr ink ing mechanisms . Tha t is, dec remen t s in food and wate r in take may be due to o the r factors, such as decreased act ivi ty or excessive stress.

In conclus ion , ECS t r e a t m e n t has been observed to p roduce a s ignif icant decrease in b o t h food and wa te r intake. These results suppor t Chorover ' s [3] c o n t e n t i o n tha t m a n y ECS induced effects a t t r i bu t ed to RA could be due to factors o the r than m e m o r y in te r fe rence , at least where food or wate r are emp loyed as reinforcers . Thus, researchers invest igat ing ECS effects on learning and m e m o - ry and who e m p l o y food or wate r as a reward should cont ro l for ECS effects on food and wate r in take indepen- den t of possible ECS effects on learning and m e m o r y .

R E F E R E N C E S

I. Adams, H. E., R. R. Hoblit and p. B. Sutker. Electroconvulsive shock, brain acetylcholinesterase activity, and memory. Physiol. Behav. 4: 113-116, 1969.

2. Calhoun, K. S., M. J. Prewett, R. D. Peters and H. E. Adams, Factors in the modification by isolation of electroconvulsive shock-produced retrograde amnesia in the rat. J. cornp, physiol. Psychol. 88: 373-377, 1975.

3. Chorover, S. U An experimental critique of "consolidation studies" and an alternate "model-systems" approach to the biophysiology of memory. In: Neural Mechanisms o f Learnhlg a*M Memory, edited by M. R. Rosenzweig and E. L. Bennett. Cambridge: MlTPress, 1976, pp. 561 582.

4. Coury, J. N. Neural correlates of food and water intake in the rat. Science 156: 1763--1765, 1967.

5. Grossman, S. P. Direct adrenergic and cholinergic stimulation of hypothalamic mechanisms. Am. J. Physiol. 2 0 2 : 8 7 2 882, 1962.

6. Grossman, S. P. Behavioral effects of chemical stimulation of the ventral amygdala. J. comp. physiol. Psychol. 57: 29-36 , 1964.

7. Madsen, M. C. and M. W. Luttges. Effect of electroconvulsive shock on extinction of an approach response. Psychol. Rep. 13: 225-226, 1963.

EFFECTS OF ECS ON FOOD AND WATER INTAKE 343

8. Miller, N. E., K. S. Gottesman and N. Berry. Dose response to carbachol and norepinephrine in the rat hypothalamus. Am. J. Physiol. 206: 1384-1388, 1964.

9. Milner, J. S. Anticholinergic blockage of water intake in the Mongolian gerbil. Psychon. Sci. 26: 135-136, 1972.

10. Mirsky, A. F. and H. E. Rosvold. The effects of electro- convulsive shock on food intake and hunger drive in the rat. J. comp. physiol. Psychol. 46: 153-157, 1953.

11. Peters, R. D., K. S. Calhoun and H. E. Adams. Modification by environmental conditions of retrograde amnesia produced by ECS. Physiol. Behav. 11: 889-892, 1973.

12. Pinel, J. P. J. A short-term gradient of ECS-produced amnesia in a one-trial appetitive learning situation. J. comp. physiol. Psychol. 68: 650-655, 1969.

13. Schiller, P. H. and S. L. Chorover. Short-term amnesic effects of electroconvulsive shock in a one-trial maze learning program. Neuropsychologia 5: 155-163, 1967.

14. Siegel, S. Nonparametric Statistics for the Behavioral Sciences. New York: McGraw-Hill, 1956.