Presence of a 5-HT7 receptor positively coupled to adenylate cyclase activation in human granulosa-lutein cells.
Although serotonin (5-HT) has been shown to stimulate progesterone production by human granulosa-lutein cells (hGLC), the receptor type and associated signaling pathway remain uncharacterized. We report here that 5-HT receptors in these cells are positively coupled to adenylate cyclase activity. Formation of cAMP was stimulated by 5-HT and its agonists in a dose- and time-dependent manner. Mianserin, amoxapine, and loxapine were equipotent in antagonizing 5-HT-induced cAMP formation. For both cAMP formation in cells and adenylate cyclase assay using membrane fractions, the rank order of potency for agonists of 5-HT were: 5-carboxy-aminotryptamine >5-HT> or =5-methoxytryptamine, consistent with a typical pharmacological profile of human 5-ht7 (h5-ht7) receptor. Sequence data of amplified complementary DNA fragments reverse transcribed from hGLC RNA revealed complete identity with published sequence of h5-ht7 receptor complementary DNA. Northern analysis showed the presence of 2.8-kb h5-ht7 transcripts in hGLC. The three variants h5-ht7A, h5-ht7B, and h5-ht7D were also detected in hGLC. Preincubation of hGLC with 5-HT (10(-8)-10(-6) M) resulted in a marked reduction in the cAMP response when the cells were subsequently stimulated with gonadotropin, and this heterologous desensitization could be reversed by 5-ht7 receptor antagonist clozapine. These data demonstrate that h5-ht7 receptor is present and stimulate cAMP formation in hGLC. In addition, the h5-ht7 receptor seems to be implicated in the heterologous down-regulation hCG-stimulated cAMP response in hGLC, with a possible ramification for luteal insufficiency.
Graveleau
C
C
Institute for Hormone and Fertility Research, University of Hamburg, Germany.
Paust
H J
HJ
Schmidt-Grimminger
D
D
Mukhopadhyay
A K
AK
D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D015152:Blotting, Northern; D015139:Blotting, Southern; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D015536:Down-Regulation / Q000235:genetics; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006107:Granulosa Cells / Q000201:enzymology*; D006801:Humans; D014975:Lutein / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology; D011374:Progesterone / Q000378:metabolism; D011967:Receptors, Gonadotropin / Q000096:biosynthesis; D011985:Receptors, Serotonin / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013256:Steroids / Q000096:biosynthesis
D011967:Receptors, Gonadotropin; D011985:Receptors, Serotonin; D013256:Steroids; C104425:serotonin 7 receptor; D011374:Progesterone; D000242:Cyclic AMP; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D000262:Adenylyl Cyclases; D014975:Lutein