Localization, identification, and action of galanin in the frog adrenal gland.
The distribution of galanin-like immunoreactivity was studied in the adrenal gland of the frog Rana ridibunda using the indirect immunofluorescence technique. A dense network of varicose fibers immunoreactive to galanin was found in the adrenal tissue. A combination of HPLC analysis and RIA detection was used to characterize galanin-like immunoreactivity in frog adrenal gland extracts. The elution profile revealed the existence of a single form of galanin exhibiting the same retention time as synthetic frog galanin. The possible involvement of galanin in the regulation of corticosteroid secretion was investigated in vitro using a perifusion system for frog adrenal slices. For concentrations ranging from 10(-9) to 3 x 10(-6) M, synthetic frog galanin induced a dose-dependent inhibition of corticosterone and aldosterone release. Repeated pulses of galanin (10(-6) M), given at 90-min intervals, resulted in a reproducible inhibition of corticosteroid secretion without any apparent tachyphylaxis. During prolonged administration of galanin (10(-6) M), the steroidogenic effect of ACTH (10(-9) M) was significantly reduced. In contrast, galanin did not attenuate the stimulation of corticosteroid secretion induced by the angiotensin II analog [Sar1,Val5]angiotensin II. These results show the occurrence of galanin in fibers innervating the frog adrenal gland. The data also demonstrate that synthetic galanin inhibits spontaneous and ACTH-induced corticosteroid release. Taken together, these findings suggest that galanin, released by nerve fibers in the adrenal tissue, can act locally as a modulator of steroid secretion.
Gasman
S
S
European Institute for Peptide Research, Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U-413, UA Centre National de la Recherche Scientifique, University of Rouen, Mont-Saint-Aignan, France.
Vaudry
H
H
Cartier
F
F
Tramu
G
G
Fournier
A
A
Conlon
J M
JM
Delarue
C
C
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D003345:Corticosterone / Q000037:antagonists & inhibitors / Q000378:metabolism; D019004:Galanin / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology; D011895:Rana ridibunda; D014018:Tissue Distribution
D000451:Mineralocorticoid Receptor Antagonists; D000450:Aldosterone; D019004:Galanin; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone