Electrophysiological properties of neurons in the caudal ventrolateral medulla projecting to the paraventricular nucleus of the hypothalamus in XXXX .

@entity3160 @entity1338 @entity4486 @entity4774 @entity2647 @entity35
Extracellular recordings were made from neurons in the caudal ventrolateral medulla in @entity4774 - @entity4486 -anesthetized @entity35 . Stimulation of the paraventricular nucleus (PVN) in the hypothalamus evoked antidromic action potentials in 71 neurons. On the basis of antidromic spike latencies, these neurons could be divided into fast- (24 neurons) and slow-conducting cell groups (47 neurons). Slow-conducting cells showed irregular and slow spontaneous discharges, while a majority of the fast-conducting cells did not show spontaneous discharges. The spontaneous activity of slow-conducting cells was suppressed by i.v. @entity1338 administration. The effects of @entity1338 could be consistently reversed by administration of the alpha 2-adrenergic antagonist, @entity3160 . The responses by @entity1338 and @entity3160 remained unimpaired in baroreceptor-denervated @entity35 . Vagus nerve stimulation produced an excitation in 80% of slow-conducting cells tested. Baroreceptor activation induced by i.v. administration of @entity2647 inhibited about half of slow-conducting cells tested. Similar elevation of blood pressure in baroreceptor-denervated @entity35 did not show any effect. These physiological and pharmacological properties of slow-conducting cells were similar to those previously reported for catecholaminergic cells in other parts of the brain. The results show the existence of two different populations among neurons in the caudal ventrolateral medulla which project directly to the PVN, and suggest that the presumed A1 catecholaminergic cells are involved in the afferent pathway from cardiovascular baroreceptors and the vagus nerve to the PVN.
