Brain Catecholaminergic Mechanisms and Hypertension

Brain catecholaminergic neuronal systems play an important role in the control of arterial blood pressure [1, 9]. A role can be attributed to norepinephrine and epinephrine in this respect, while some evidence for the involvement of dopamine is also available. Neuronal systems employing norepinephrine and epinephrine as neurotransmitters appear to be located in strategic positions in the brainstem, thereby enabling these substances to participate in cardiovascular control [5, 15, 14, 21]. An inhibiting role for catecholamines in blood pressure regulation is supported by the fact that antihypertensive drugs such as clonidine and α-methyldopa appear to exert their central blood pressure lowering action via activation of catecholaminergic receptors in the brain [9, 11, 20, 29]. Malfunction of the central nervous control of blood pressure, in particular of the catecholaminergic systems, may be a cause of essential hypertension [7]. In this paper we will briefly review the hypotensive effects of microinjections of catecholamines into the nucleus of the solitary tract in the medulla oblongata. In addition, altered CNS catecholaminergic neurotransmission in spontaneously hypertensive rats will be considered in relation to hypertension.