AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 3 407-R411, Copyright © 1988 by American Physiological Society
Enhanced ANG II activity in anterior pituitary cell aggregates from hypertensive rats
W. Robberecht and C. Denef
Laboratory of Cell Pharmacology, School of Medicine, University of Leuven, Belgium.
Pituitary cell reaggregates from 14-day-old and adult spontaneously
hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were cultured in
serum-free, chemically defined medium supplemented with the thyroid hormone
triiodothyronine and the glucocorticoid dexamethasone. After 1 wk in
culture, aggregates were transferred into a perifusion system, and the
effect of angiotensin II (ANG II) on prolactin (PRL) and growth hormone
(GH) release was studied. In aggregates from adult SHR, ANG II displayed a
significant and dose-dependent GH releasing activity, whereas a negligible
effect or no effect was seen in aggregates from adult WKY. In contrast, no
difference in the stimulation of PRL release by ANG II was found. To
exclude the possibility that the enhanced GH responsiveness was secondary
to longstanding hypertension, aggregates from animals in the
prehypertensive stage were studied. Both the GH and PRL responses to ANG II
were significantly higher in aggregates from 14-day-old SHR than in
aggregates from 14-day-old WKY. These data indicate that abnormal GH and
PRL responses to ANG II exist in pituitary cell aggregates from SHR long
before hypertension develops. Because these differences were found in
pituitary cells maintained in culture for 1 wk, they do not seem to be
secondary to changes in brain regulation of pituitary function but rather
are caused by factors intrinsic to the pituitary.
