APStracts 2:0240R, 1995.

Paraventricular nucleus efferents influence area postrema neurons. Smith, P. M., and A. V. Ferguson. Dept. of Physiology, Queen's University, Kingston, ONT. Canada K7L 3N6

APStracts 2:0240R, 1995.

Extracellular single unit recordings were obtained from area postrema neurons (AP) and peristimulus histograms used to determine the effects of paraventricular nucleus (PVN) stimulation on these cells anaesthetized Sprague Dawley rats. Of 91 AP cells tested, 30.8% responded to PVN stimulation with a short latency (28.2 +/- 3.3msec, mean +/- S.E.M.), short duration (49.3 +/- 8.0msec) excitation while 8.6% were inhibited. In animals that had stimulation sites outside of PVN (non-PVN), only 4 of the 72 AP cells tested (5.6%) were influenced by stimulation. These excitatory effects of PVN stimulation on AP neurons were unaffected by V1 receptor blockade. Of 93 nucleus tractus solitarius (NTS) cells tested, 38.9% responded to PVN stimulation with a short latency (18.5 +/- 2.4msec), short duration (48.8 +/- 9.6msec) excitation and 22.2% with short latency (20.75 +/- 4.1msec), long duration (204.4 +/- 44.9msec) inhibitions. In contrast, non-PVN stimulation sites influenced only 19% of NTS neurons tested all of which were excited. These data demonstrate that activation of PVN neurons elicits excitatory effects on the majority of AP neurons influenced. They further emphasize the potential significance of descending hypothalamic inputs in controlling neuronal activity in this CVO.

Received 23 January 1995; accepted in final form 22 August 1995.
APS Manuscript Number R49-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 15 September 1995.