Effects of catecholamines infused into the brain of young chickens

Abstract

Summary1. (-)-Noradrenaline, (-)-a-methylnoradrenaline and (-)-isoprenaline were infused into various brain regions of 12-21 day chicks. When infused into the hypothalamic area, but not the cerebral hemisphere or posterior mesencephalon, these amines produced behavioural sleep, lowered temperature and blood pressure and reduced oxygen consumption; electrocortical sleep activity usually ensued but this was not marked and frequently dissociation between electrocortical activity and behaviour occurred. After monoamine oxidase inhibition, which prolonged the action of noradrenaline, dopamine had similar effects.2. The effects of the catecholamines were prevented or substantially reduced by pretreatment with phenoxybenzamine given intravenously or into the hypothalamus but not by intravenous injection of propranolol. However, intrahypothalamic infusion of propranolol prevented the temperature, but not the behavioural effects of noradrenaline. The implications of this are discussed. 3. That the effects were similar but more intense, apart from electrocortical changes, and of longer duration than those seen after intravenous injection of catecholamines suggests that in young chicks these amines penetrate from the blood into the brain and elicit their effects through a localized region, presumably the hypothalamus.

Adrenergic control of tendon jerk reflexes in man

“…The blocking drug, thymoxamine, is considered to be specific for a-adrenoceptors (Birmingham, Akubue & Szolcsanyi, 1967) and this raises the possibility that the central receptors which this drug was influencing were a-adrenoceptors. This conclusion was reached for receptors in the hypothalamic region of the chick (Marley & Stephenson, 1969) and of man (Besser, Butler, Ratcliffe, Rees & Young, 1970). The unsatisfactory results of our experiments with blocking drugs make a definite conclusion about the nature of these receptors premature, but it should be noted that while thymoxamine had a marked and consistent effect on jerk responses, propranolol produced no change.…”

Effects of Catecholamines on Thermoregulation in Pigeons

“…If it were abolished by propranolol it would suggest that p-adrenoceptor activation may contribute to the hypothermic effects of the catecholamines. Indeed, Marley & Stephenson (1970) are of the opinion that the hypothermia caused by the catecholamines in the chickens is mediated through activation of ,B-receptor or a catecholamine receptor with a and , characteristics as it was blocked by both phenoxybenzamine and propranolol microinfused into the hypothalamus. Intravenous injection of phenoxybenzamine but not of propranolol also blocked the hypothermia, suggesting the existence of a blood-brain barrier for propranolol.…”

“…The site of action is the hypothalamus because Marley & Stephenson (1970) obtained hypothermia on microinfusion of the catecholamines into the hypothalamus of chicken. It would thus appear that the catecholamines have the same effect on temperature in birds as in cats, dogs and monkeys, when acting on the hypothalamus.…”

Tryptamines and Some Other Substances Affecting Waking and Sleep in Fowls

“…Catecholamines infused into the hypothalamus of young (Marley & Stephenson, 1970) and adult fowls (Marley & Nistico, 1972) Opposite effects of these amines on body temperature have been noted in a number of species (see Bligh, 1973, for references), although there is no agreed interpretation of their mode of production.…”