Food intake of domestic fowl injected with adrenergic agonists and antagonists into the hepatic portal vein

Exogenous cholecystokinin octapeptide in broiler chickens: satiety, conditioned colour aversion, and vagal mediation

Intraperitoneal injections of 3.5, 7.0, 14.0, and 28.0 micrograms/kg of CCK-8 into free-feeding broiler chickens significantly reduced food intake and delayed feeding (p < 0.05). To determine whether CCK can condition preference or aversion and to investigate the latency and the reversal of the effect, a low (2 micrograms/kg) and a high (14 micrograms/kg) dose of CCK-8 were administered using the coloured food paradigm. One colour, the conditioning stimulus (CS+), was paired with injections of CCK-8; the other colour was paired with injections of saline (CS-). The 2 micrograms/kg dose of CCK-8 neither reduced food intake nor conditioned a colour aversion. The 14 micrograms/kg dose significantly reduced food intake and conditioned a colour aversion (p < 0.05). When vagotomy was performed, the 14 micrograms/kg dose of CCK suppressed feeding in sham-operated birds (p < 0.05) but not in vagotomized birds (p > 0.05). A significant aversion for the food paired with CCK was obtained in sham-operated birds (p < 0.001) but not in vagotomized birds (p > 0.05). It was concluded that IP injections of CCK-8 reduce food intake in broiler chickens and that chicks can learn to associate the colour of the food with injections of CCK, developing an aversion. It was also shown that the vagus nerve mediates the CCK satiety effects and that aversion conditioning to CCK is dependent upon intact vagal innervation of the viscera.

Phentolamine stimulates insulin release and glucose clearance and suppresses food ingestion

In Experiment One, phentolamine (PTA), an alpha-adrenergic blocker, was injected in rats at doses of 0, 50, 100, 200, and 300 micrograms/kg following a 4-hr fast. Measurement of food intake 1-hr postinjection revealed that 300 micrograms/kg PTA reduced food intake. Experiment Two evaluated the potential aversiveness of 300 micrograms/kg PTA. Four-hour fasted rats were adapted to a milk diet as the only food source during a 1-hr intake measurement period. After the 15-day adaptation period, three separate groups of animals (n = 8 per group) received the milk with cherry flavoring added and infections of either 1% body weight 0.9 NaCl, isosmotic LiCl or 300 micrograms/kg PTA. Only those subjects that had received LiCl injections developed a reliable aversion to the cherry-flavored milk. The final experiments subdivided the 1-hr feeding period into three 20-min segments and, in separate animals, food intake or plasma insulin and glucose changes were assessed. The animals were assigned to one of two groups receiving either 300 micrograms/kg PTA or equivolume 0.9% NaCl. PTA-injected subjects showed an immediate modest enhancement of insulin release during the first 20-min feeding segment following injection, compared to controls, while blood glucose levels decreased but never differed reliably between groups. Food intake was reliably suppressed in the second and third 20-min segments for the PTA-injected rats. We advance that PTA by enhancing glucose clearance may be reducing ingestion.