Physiology& Behavior, Vol. 49. pp. 153-154. ©Pergamon Press plc, 1991. Printed in the U.S.A.
0031-9384/91 $3.00 + .00
Psychological Aspects of Insulin-Induced Thirst I J. I. B R I M E , P. L O P E Z - S E L A , R. B E R N A R D O , M. C O S T A L E S , F. D I A Z , B. M A R f N A N D M. V I J A N D E
Area de Fisiologfa, Departamento de Biolog[a Funcional Universidad de Oviedo y Hospital Covadonga, Oviedo, Spain (FISss 87/1036) R e c e i v e d 5 July 1990
BRIME, J. I., P. LOPEZ-SELA, R. BERNARDO, M. COSTALES, F. DIAZ, B. MAR~N AND M. VIJANDE. Psychological aspects of insulin-induced thirst. PHYSIOL BEHAV 49(1) 153-154, 1991.--Fifteen normal volunteers received one insulin injection or saline in two nonconsecutive days. At 0', 30', 60' and 90' water intake was measured. Simultaneously subjective thirst and hunger were recorded by running a set of psychological tests. Water intake was higher after insulin than saline at 60' and 90'. Insulin increases thirst sensation even before the sensation of hunger. Insulin
ALTHOUGH the homeostatic mechanisms of thirst are well studied, less is known about the physiological mechanisms of normal drinking. Approximately two-thirds of drinking occurs around meal time in animals and humans. Insulin is a dipsogenic substance in rats as has been previously reported (1). However, the mechanisms of insulin-induced drinking are not totally understood. The present work on humans was aimed to study the possibility that insulin could change oropharyngeal and gastric sensations related with thirst and hunger. Fifteen normal volunteers (8 males and 7 females, 19-36 years of age, 45-90 kg of body weight) were studied. The volunteers received, under a double-blind schedule, one insulin injection (Actrapid, Novo 0.1 U/kg b.wt.) or saline on two nonconsecutive days. All subjects were fasted since the night previous to the tests. Prior to starting each run, a glass of water was offered. Water intake was measured by weighing the glass with a precision of 0.1 g. From this moment on water, but no food, was
available ad lib. At 0', 30', 60' and 90', simultaneously with measurement of water intake, subjective thirst and hunger were recorded by running a set of psychological tests. The subjects were asked to mark with a pen their subjective rating on an analogic scale 10 cm long, upon which the left side represented the minimum and the right side the maximum of sensation (2). Water intake was higher after insulin treatment than after saline. The difference was significant (p