Medullary sympathoexcitatory neurons are inhibited by activation of
the medial prefrontal cortex in the rat.
Verberne, Anthony J. M.
University of Melbourne, Clinical Pharmacology and Therapeutics
Unit, Austin Hospital, Heidelberg, Victoria 3084, AUSTRALIA
APStracts 2:0315R, 1995.
Electrical stimulation of the medial prefrontal cortex (MPFC) reduces
arterial blood pressure. To investigate the mechanism of this
response, the effects of electrical and chemical stimulation of the
MPFC on splanchnic and lumbar sympathetic nerve discharge and on the
discharges of barosensitive neurons of the rostral ventrolateral
medulla (RVLM) were studied in halothane-anesthetised rats.
Electrical stimulation (20 Hz, 1 ms, 100 _A, 10 s) of the MPFC
produced depressor responses and sympathoinhibitory responses
(reduced discharge of the splanchnic sympathetic nerve).
Microinjection of glutamate (10 nmol/ 100 nl) into the MPFC also
reduced arterial blood pressure and sympathetic discharge. Electrical
stimulation (0.5 Hz, 1 ms pulse pairs, 3 ms interval, 150-300 _A)
produced distinct patterns of splanchnic and lumbar sympathetic nerve
discharge. A clear sympathoinhibitory phase with an onset latency of
146+/-14 ms was observed only in the case of the splanchnic
sympathetic nerve activity. Electrical stimulation at depressor sites
within the MPFC also inhibited the discharge of 10/21 RVLM
barosensitive neurons tested. RVLM neurons were never excited by MPFC
stimulation. These results indicate that the MPFC contains neurons
which form part of a central sympathoinhibitory pathway.
Received 14 June 1995; accepted in final form 18 October 1995.
APS Manuscript Number R360-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95