Activation of 5-HT(7) receptor in rat glomerulosa cells is associated with an increase in adenylyl cyclase activity and calcium influx through T-type calcium channels.
Serotonin (5-HT) stimulates aldosterone secretion from the rat adrenal gland through 5-HT(7) receptors. The aim of the present study was to investigate the transduction mechanisms associated with activation of 5-HT(7) receptors in rat glomerulosa cells. The stimulatory effect of 5-HT on aldosterone secretion and cAMP formation was significantly reduced by the 5-HT(7) receptor antagonist LY 215840. Pretreatment of cells with the adenylyl cyclase inhibitor SQ 22536 or the PKA inhibitor H-89 markedly attenuated the effect of 5-HT on aldosterone secretion. Conversely, type 2 and 4 phosphodiesterase inhibitors potentiated the 5-HT-induced stimulation of aldosterone secretion. Administration of 5-HT in the vicinity of cultured glomerulosa cells induced a slowly developing and robust increase in cytosolic calcium concentration ([Ca(2+)](i)). The effect of 5-HT on [Ca(2+)](i) was suppressed by mibefradil, a T-type calcium channel blocker. Patch-clamp studies confirmed that 5-HT activated a T-type calcium current. Mibefradil also induced a dose-dependent inhibition of 5-HT-induced aldosterone secretion. The sequence of events associated with activation of 5-HT(7) receptors was investigated. The PKA inhibitor H-89 markedly attenuated both the [Ca(2+)](i) response and the activation of T-type calcium current induced by 5-HT. In contrast, reduction of the calcium concentration in the incubation medium did not affect 5-HT- induced cAMP formation. Preincubation of glomerulosa cells with cholera toxin abolished the stimulatory effect of 5-HT on aldosterone secretion, but pertussis toxin had no effect. Taken together, these data demonstrate that, in rat glomerulosa cells, activation of native 5-HT(7) receptors stimulates cAMP formation through a G(salpha) protein, which in turn provokes calcium influx through T-type calcium channels. Both the adenylyl cyclase/PKA pathway and the calcium influx are involved in 5-HT-induced aldosterone secretion.
Lenglet
Sebastien
S
European Institute for Peptide Research (IFRMP 23), Institut National de la Santé et Recherche Médicale Unité-413, Unité Affiliée Centre National de la Recherche Scientifique, University of Rouen, 76821 Mont-Saint-Aignan, France.
Louiset
Estelle
E
Delarue
Catherine
C
Vaudry
Hubert
H
Contesse
Vincent
V
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000378:metabolism*; D002469:Cell Separation; D000242:Cyclic AMP / Q000032:analysis / Q000096:biosynthesis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D010477:Perfusion; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D015384:Zona Glomerulosa / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*
D015220:Calcium Channels; D020747:Calcium Channels, T-Type; D004791:Enzyme Inhibitors; D010726:Phosphodiesterase Inhibitors; D011985:Receptors, Serotonin; C104425:serotonin 7 receptor; D012701:Serotonin; D000450:Aldosterone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D002118:Calcium