Effects of Cholinomimetic Agents Given Into the Brain of Fowls

Abstract

1 Effects of cholinomimetic agents, given into the IlIrd ventricle of adult fowls (Gallus domesticus) or infused into the hypothalamus of young chicks, were tested on behaviour, respiratory rate and body temperature. 2 Carbachol evoked behavioural and electrocortical arousal but lacked postural and respiratory effects. Contrariwise, pilocarpine increased respiratory rate and induced postural changes, i.e. abduction of the wings, but lacked other behavioural effects and did not alter electrocortical activity. Benzoylcholine induced tachypnoea, postural changes and brief electrocortical arousal. Acetylcholine was ineffective unless given with physostigmine, when electrocortical arousal, postural changes and tachypnoea developed. Methacholine induced tachypnoea and postural changes. 3 Effects of carbachol and pilocarpine were prevented by hyoscine and those of benzoylcholine by pempidine; hyoscine and pempidine were required together to prevent the effects of methacholine and to attenuate those of acetylcholine with physostigmine.

Effects of Nicotine Given Into the Brain of Fowls

“…Further support for this idea came from the finding that nicotine significantly augmented acetylcholine release from the cat cerebral cortex (Armitage, Hall & Sellers, 1969). However, in fowls, although the sleep-like behavioural and electrocortical effects of nicotine were prolonged after physostigmine, such effects were the antithesis of those after intraventricular acetylcholine and physostigmine, which evoked arousal (Marley & Seller, 1974). Consequently, acetylcholine release may not account for the behavioural and electrocortical changes induced by nicotine in fowls; intraventricular acetylcholine evoked tachypnoea as did nicotine, so acetylcholine release is feasible in this instance.…”

SOME EFFECTS OF PROSTAGLANDINS E1 AND E2 AND OF ENDOTOXIN INJECTED INTO THE HYPOTHALAMUS OF YOUNG CHICKS: DISSOCIATION BETWEEN ENDOTOXIN FEVER AND THE EFFECTS OF PROSTAGLANDINS

“…CarbachoL Carbachol lacked effect on body temperature when given alone at thermoneutrality (Marley & Seller, 1974) but when given below thermoneutrality it was found to be a potent hypothermic agent. Figure…”

“…Below thermoneutrality (160C), endotoxin fever was also antagonized by intrahypothalamic infusions of noradrenaline, 5-hydroxytryptamine and carbachol, compounds which produce hypothermia when given alone. Interestingly, carbachol lacked effect on body temperature when given at thermoneutrality (Marley & Seller, 1974). Failure of indomethacin and ETA to prevent onset of endotoxin fever and to abolish established fever make it uncertain that prostaglandins mediate endotoxin fever in chicks.…”

“…CarbachoL Carbachol lacked effect on body temperature when given alone at thermoneutrality (Marley & Seller, 1974) also hypothermic after injection into the preoptic/anterior hypothalamic area of the anteater since this species (a monotrematous mammal) has, unlike birds, evolved from the same reptilian stock as the placental mammals. Below thermoneutrality (160C), endotoxin fever was also antagonized by intrahypothalamic infusions of noradrenaline, 5-hydroxytryptamine and carbachol, compounds which produce hypothermia when given alone.…”