AJP - Endocrinology and Metabolism, Vol 273, Issue 1 E156-E163, Copyright © 1997 by American Physiological Society
Water deprivation upregulates ANG II AT1 binding and mRNA in rat subfornical organ and anterior pituitary
G. L. Sanvitto, O. Johren, W. Hauser and J. M. Saavedra
Section on Pharmacology, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
We studied angiotensin II (ANG II) receptor subtype expression in selected
brain nuclei and pituitary gland after water deprivation by in vitro
receptor autoradiography using 125I-labeled [Sar1]ANG II and by in situ
hybridization using 35S-labeled AT1A, AT1B, and AT2 receptor-specific
riboprobes. In control rats we found binding to AT1 receptors in the
subfornical organ, paraventricular nucleus, median eminence, and anterior
pituitary; AT1A mRNA expression in the subfornical organ and
paraventricular nucleus; and AT1B mRNA expression in the anterior
pituitary. No receptor mRNA was found in the median eminence. AT1 receptors
and AT1A receptor mRNA levels were increased in the subfornical organ, and,
in the anterior pituitary, AT1 receptors and AT1B receptor mRNA were
increased, only after 5 days of water deprivation. No significant changes
occurred after 1 or 3 days of water deprivation, and no regulation of ANG
II receptor expression was detected in other brain areas. Our results show
that prolonged water deprivation selectively regulates AT1 receptor
expression and AT1A and AT1B receptor mRNA levels in the subfornical organ
and anterior pituitary, respectively, supporting a role for these receptors
during sustained dehydration.
