Galanin enhances corticosterone secretion from dispersed rat adrenocortical cells through the activation of GAL-R1 and GAL-R2 receptors coupled to the adenylate cyclase-dependent signaling cascade.
Galanin is a regulatory peptide, which acts via three subtypes of receptors, named GAL-R1, GAL-R2 and GAL-R3. Reverse transcription-polymerase chain reaction demonstrated the expression of GAL-R1 and GAL-R2, but not GAL-R3 mRNAs in dispersed rat adrenal zona fasciculata-reticularis (inner) cells. The immuno-blockade of GAL-R1 and GAL-R2, but not GAL-R3, decreased the binding of [3H]galanin to dispersed cells, a complete inhibition being obtained only by the simultaneous blockade of both receptor subtypes. Galanin stimulated corticosterone and cyclic-AMP release from dispersed inner rat adrenocortical cells, while inositol triphosphate production was not affected. Again these responses to galanin were reversed by both the GAL-R1 and GAL-R2, but not the GAL-R3 immuno-blockade. The adenylate cyclase inhibitor SQ-22536 and the protein kinase (PK) A inhibitor H-89 abolished the corticosterone response of dispersed cells to galanin, while the phospholipase C inhibitor U-73122 and the PKC inhibitor calphostin-C were ineffective. We conclude that rat inner adrenocortical cells express GAL-R1 and GAL-R2 as mRNA and protein, and galanin stimulates corticosterone secretion acting via these receptor subtypes which are both coupled to the adenylate cyclase/PKA-dependent signaling pathway.
Andreis
Paola G
PG
Department of Anatomy and Physiology, Section of Anatomy, University of Padua, I-35121 Padua, Italy.
Malendowicz
Ludwik K
LK
Rebuffat
Piera
P
Spinazzi
Raffaella
R
Ziolkowska
Agnieska
A
Nussdorfer
Gastone G
GG
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000302:Adrenal Cortex / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D003345:Corticosterone / Q000378:metabolism*; D019004:Galanin / Q000494:pharmacology*; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D044091:Receptor, Galanin, Type 1 / Q000378:metabolism*; D044092:Receptor, Galanin, Type 2 / Q000378:metabolism*; D015398:Signal Transduction
D044091:Receptor, Galanin, Type 1; D044092:Receptor, Galanin, Type 2; D019004:Galanin; D000262:Adenylyl Cyclases; D003345:Corticosterone