title: Noradrenergic afferents facilitate the activity of tuberoinfundibular neurons of the hypothalamic paraventricular nucleus.
abstract: The role of ascending noradrenergic projections of medullary origin in regulating the activity of tuberoinfundibular neurons of the hypothalamic paraventricular nucleus (PVN) was examined in pentobarbital-anesthetized male Sprague-Dawley rats. Discrete electrical stimulation of either the A1 or the A2 noradrenaline cell group areas of the caudal medulla enhanced the probability of firing in a substantial proportion of antidromically identified tuberoinfundibular PVN cells tested. Notably, no inhibitory effects were observed. Destruction of the PVN noradrenergic terminal plexus by local application of the neurotoxin 6-hydroxydopamine 1 day prior to electrophysiological experiments abolished the effects of both A1 and A2 stimulation. These findings indicate that noradrenergic afferents can exert a facilitatory influence on the activity of a population of tuberoinfundibular PVN neurons, thus supporting earlier suggestions that central noradrenergic structures can enhance the release of certain anterior pituitary hormones.
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004594:Electrophysiology; D005071:Evoked Potentials; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D016627:Oxidopamine; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D006892:Hydroxydopamines; D016627:Oxidopamine; D009638:Norepinephrine