Extracellular atp as an autocrine/paracrine regulator of prl
release.
Nu[circumflex]uez, Lucia, Carlos Villalobos, and L. Stephen Frawley.
Department of Cell Biology and Anatomy, Medical University of South
Carolina, Charleston, South Carolina 29425
APStracts 4:0051E, 1997.
Recent evidence demonstrates that ATP, co-stored with a number of
hormones and neurotransmitters in secretory granules, is co-released
during exocytosis of these agents. Here, we explored the possibility
that extracellular ATP subserves an autocrine/paracrine role in the
regulation of PRL release by subjecting rat pituitary cells to
various experimental manipulations aimed at evaluating putative
interactions between ATP and mammotropes. Our results strongly
support the view that ATP functions as a local regulator of PRL
secretion. To be more specific, we observed that ATP is released in a
predictable manner by physiologically relevant secretagogues which
are reasonably targeted to mammotropes. Moreover, we found that ATP
can act directly on pituitary cells to stimulate the release of PRL
from most (if not all) mammotropes. Finally, we determined that
antagonism or removal of ATP leads to a diminution of PRL export from
pituitary cells cultured under basal or TRH-stimulated conditions. On
the basis of these results, we propose that ATP acts locally to
amplify and prolong the PRL secretory response elicited by a more
traditional hypophysiotropic signal.
Received 20 November 1996; accepted in final form 12 February
1997.
APS Manuscript Number E581-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 5 March 1997