Cardiovascular function of the paraventricular nucleus of the hypothalamus.

Recent evidence is showing that the paraventricular nucleus (PVN) of the hypothalamus plays a key role in autonomic regulation. Studies by the author of the PVN neurones that project to the spinal cord are reviewed. These neurones are inhibited by arterial baroreceptors and excited or inhibited by pulmonary/cardiac vagal afferents. Volume load or low dose atrionatriuretic peptide can stimulate vagal afferents to excite PVN-spinal neurones. Ibotenic acid-induced lesions of PVN-spinal neurones abolish a reflex increase in renal vascular conductance following volume load. This effect appears to be independent of the PVN-vasopressin or oxytocin-containing neurones which directly excite spinal sympathetic neurones. It is suggested that different chemically coded PVN-spinal neurones produce differential effects on spinal cardiovascular neurones, either monosynaptically or via interneurones.