Neurophysin expression is stimulated by dopamine d1 agonist in
dispersed hypothalamic cultures.
Mathiasen, J. R., E. R. Larson, M. A. Ariano, and C. D. Sladek.
Departments of Physiology and Biophysics and Neuroscience, Finch
University of Health Sciences/The Chicago Medical School, North
Chicago, Illinois 60064-3095
APStracts 2:0242R, 1995.
We have exposed primary dispersed hypothalamic cultures from 14-day
old fetal Sprague-Dawley rats to substances known to either elevate
cAMP levels or increase vasopressin (VP) secretion. The levels of VP
in the medium collected from the cultures were determined by
radioimmunoassay and the number of neurophysin (NP) positive cells
following immunohistochemistry were counted. cAMP elevating agents,
3-isobutyl-1-methylxanthine (IBMX, 200 [mu]M) and forskolin (25
[mu]M; together, I/F) maintained NP synthesis and VP secretion in 19
day cultures. I/F replacement by K+ (28 mM), isoproterenol (10
[mu]M), glutamate (10 [mu]M) or bicucculline (10 [mu]M) during the
last week of culture resulted in maintainence of NP expression and
transient stimulation of VP secretion, but these agents did not
induce NP expression independent of I/F treatment. In contrast,
exposure to the dopamine D1 agonist SKF 38393 (SKF, 10 [mu]M)
significantly increased NP expression independently, and after
replacement of I/F. Dopamine D1A receptors were detected by
immunofluorescence on NP expressing cells providing a morphological
basis for this response. These results suggest a role for D1A
receptors in the regulation of VP gene expression.
Received 25 May 1995; accepted in final form 22 August 1995.
APS Manuscript Number R313-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 15 September 1995.