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N J Kenney

Publications and source records attributed to N J Kenney.

26 records · Page 2Linked to original sources

Peptides and the control of meal size.

There are now a large number of experiments demonstrating that peripheral administration of exogenous cholecystokinin or its synthetic analogue, CCK-8, reduces meal size in a number of species. The peptide interacts with other factors which influence satiety, and treatments thought to be effective in eliciting secretion of cholecystokinin have predictable effects on meal size. Cholecystokinin is effective in the genetically obese Zucker rat, obese rats with lesions of the ventromedial hypothalamus, and subdiaphragmatically vagotomized rats. Somatostatin and bombesin are also reasonable candidates for satiety factors. Intraperitoneal naloxone reduces meal size in rats, and beta-endorphin injected intraventricularly causes an increase in meal size of 50% over 30 minutes. We conclude that cholecystokinin and bombesin may interact in weight regulation and control of meal time food intake.

Appetite↗

Similarities in the regulatory patterns of pregnant and cycling rats.

The patterns of food intake, water intake and body weight of the female rat during the estrous cycle and pregnancy were determined. During the 4-day estrous cycle, intake and body weight were reduced on the day of ovulation. In contrast, animals with 5-day estrous cycles reduced intake and body weight for 2 days, the day prior to ovulation as well as on the day of ovulation. Intake of pregnant rats around the time of birth was compared to that of cycling females and similarities were observed. The peripartum pattern of food intake was systematically related to the length of the gestation period. Rats that littered 22 days after mating showed depressed food intake only on the day of birth. Those with 23-day gestation periods decreased food intake both on the day of birth and on the following day. The similarities in the intake patterns during 4- and 5-day estrous cycle to that of the peripartum segment of 22- and 23-day pregnancies suggest that there may be common neuroendocrine factors controlling these behaviors during the two reproductive periods.

Animals↗

Antidipsogenic role of the E-prostaglandins.

Prostaglandin E1 (PGE1) is antidipsogenic when administered into the lateral cerebral ventricle of the rat. In these experiments PGE1, at a dose of 1 microgram, suppressed water intake induced by centrally administered angiotensin II (AII) or carbachol, subcutaneously administered polyethylene glycol, and water deprivation. Even at this high dose, PGE1 did not reduce water intake due to cellular dehydration. As the dose of PGE1 was reduced, its suppressant effects became more specific to AII-induced drinking, with a dose of 10 ng yielding a significant suppression only in the case of AII-induced drinking. Even at a high dose (1 microgram), the PGE1 suppression of ingestion was specific to water intake. Although PGE1-treated rats reduced food intake if they were not hydrated prior to access to food, no reduction in food intake was seen when they received water by gavage before food presentation. Since PGE-like substances are synthesized in the brain, these data suggest the possibility that the prostaglandin may be involved in the regulation of water balance as a component of a reciprocal system in which water intake initiated by the activation of the renin-angiotensin system is halted by the synthesis and release of PGE.

Angiotensin II↗