Cholinergic and catecholaminergic interaction and fluid intake in the rat.

The effect of simultaneous topical application of adrenergic agonists was investigated on the polydipsia caused by direct carbachol (CCh) stimulation of the rat brain. In addition, fluid selection (4-choice arrangement) was studied. Noradrenaline and isoprenaline fully antagonized the CCh effect after either intracerebroventricular, intraseptal or intrapreoptic application. Phenylephrine inhibited CCh polydipsia after intracerebroventricular or intrahypothalamic but not after intraseptal injection. Previous experiments had shown that adrenergic agonists also exerted a marked modulatory influence on an affective behavioural reaction pattern (rage reaction) of the cat. The results of the present experiments corroborate the assumption that, also in non-striatal brain structures, adrenergic modulation of cholinergic behavioural patterns is perhaps a more general and important phenomenon than had been assumed so far.