Splanchnicotomy increases adrenal sensitivity to acth in non
-stressed rats.
Jasper, Michael S., and William C. Engeland.
Department of Surgery, RI Hospital and Section of Neurobiology,
Brown University, Providence, RI 02902; Departments of Surgery and of
Neuroanatomy and Cell Biology, University of Minnesota, Minneapolis,
MN 55455
APStracts 4:0096E, 1997.
Awake rats demonstrate an ultradian rhythm in adrenal secretion of
corticosterone. Splanchnic denervation in unstressed rats increases
the frequency of corticosterone pulses, revealing an inhibitory
function of adrenal innervation. In contrast, one day after surgical
stress, adrenal denervation reduces adrenal pulsatility, suggesting a
stimulatory function of adrenal innervation. To test whether neural
modulation of pulsatile secretion was due to a direct effect of the
splanchnic nerve on adrenal sensitivity to ACTH, rats treated with
dexamethasone were administered repetitive pulses of ACTH and the
amplitude of corticosterone responses was determined. Intact (CTRL)
and splanchnicotomized (SPLNX) rats were tested at two or five days
after surgery. Five days after surgery, adrenal responsiveness in
CTRL animals was reduced compared to SPLNX animals. However, no
differences were seen two days after surgery. To determine if the
reduction in adrenal responsiveness involved a cellular or organ
level mechanism, dispersed adrenal cortical cells isolated from
intact or denervated adrenal glands were stimulated with ACTH and
corticosterone secretion was determined. Consistent with in vivo
results, denervation increased the responsiveness of adrenal cells
obtained five, but not one or two days after surgery. These findings
support a neurally mediated inhibition of adrenal sensitivity to ACTH
in unstressed rats.
Received 7 November 1996; accepted in final form 27 March 1997.
APS Manuscript Number E563-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 13 May 1997