Control of circulation by cerebral catecholaminergic and histaminergic mechanisms.

Catecholamines are formed, released and metabolized in the cerebral regions known to regulate the cardiovascular system. The release of catecholamines in these brain areas is associated with changes in cardiovascular function. Injections of exogenous catecholamines into certain brain regions induce cardiovascular changes and mimic the effects of the release of endogenous catecholamines in the same regions. In addition, drugs with selective effects on cerebral catecholamine functions also induce cardiovascular changes. Changes in cerebral catecholamines have also been found in arterial hypertension. Taken together, these observations provide strong evidence that cerebral catecholaminergic mechanisms have a crucial role in both the normal and pathological control of circulation. Cerebral catecholaminergic mechanisms also mediate, at least in part, the therapeutic effects of clonidine, alpha-methyldopa and some other antihypertensive drugs. Recent findings suggest that histaminergic mechanisms in the brain may also be important in the control of circulation and in the mediation of drug effects. Since the cerebral mono-aminergic systems are necessary for the physiological control of circulation, it is likely that the cerebral catecholaminergic and possibly histaminergic pathways are also involved in the mediation of the effects of psychological stress factors on the cardiovascular system.