The action of the A1 noradrenergic region on phasically firing neurons in the rat paraventricular nucleus.

Electrical stimulation of the rat A1 noradrenergic region produced orthodromic inhibition (34%), excitation (23%) or excitation-inhibition sequence (25%) of the spontaneous activity of phasically firing units in the paraventricular nucleus of the hypothalamus (PVH). Excitatory responses could be distinguished into two types on the basis of their latency and duration. Both the primary and post-excitatory inhibitory responses were significantly attenuated by intravenous injection of propranolol, a beta-adrenoceptor antagonist, whereas neither type of excitatory response was affected.