Participation of galanin in baroreflex inhibition of heart rate by
hypothalamic paraventricular nucleus in the rat.
Chen, Ying-Ling, Samuel H. H. Chan, and Julie Y. H. Chan.
Institute of Physiology and Center for Neuroscience, National Yang
-Ming University, Taipei 11221, Taiwan and Department of Medical
Research, Veterans General Hospital-Taipei, Taipei 11217, Taiwan,
Republic of China
APStracts 3:0226H, 1996.
We investigated the role of galanin (GAL) in the suppression of
barorecep tor reflex (BRR) response by the paraventricular nucleus of
the hypothala mus (PVN) in adult, male Sprague-Dawley rats that were
anesthetized with pentobarbital sodium. Electrical stimulation (10-s
train of 1-ms rec tangular pulses, at 20-40 [mu]A and 10-20 Hz) of,
and microinjection of L-glutamate (1 nmol) into, the PVN
significantly inhibited BRR response to transient hypertension
induced by phenylephrine (5 [mu]g/kg, iv). Such a PVN-induced BRR
suppression was appreciably antagonized by local administration of
GAL antiserum (1:20), but not heat-inactivated GAL antiserum (1:20),
to the NTS bilaterally. Microinjection of GAL (100 pmol) into the NTS
bilaterally also resulted in a GAL antiserum-reversible inhibi tion
of the BRR response. Immunohistochemical results demonstrated that
the distribution of GAL-containing neurons in the parvocellular
subnucleus of the PVN overlapped substantially with the hypothalamic
loci upon which electrical or chemical activation elicited
suppression of the BRR response that was significantly blunted by
microinjection of GAL antiser um into the NTS. These results suggest
that PVN may participate in central cardiovascular regulation by
suppressing the BRR response via galaninergic neurotransmission at
the NTS.
Received 18 March 1996; accepted in final form 13 May 1996.
APS Manuscript Number H254-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96