Acute stimulation of intestinal cell calcium influx induced by 17 beta-estradiol via the cAMP messenger system.
Recent studies have provided evidence for nuclear estrogen receptor-mediated calcium transport in intestinal mucosal cells. The possibility that, in addition, estrogens directly stimulate intestinal Ca2+ fluxes through second-messenger pathways was investigated. Exposure of enterocytes isolated from female rat duodenum to low physiological levels of 17 beta-estradiol (10(-11), 10(-10) and 10(-8) M) rapidly (1-10 min) increased (50-170%) cell 45Ca2+ influx. 17 alpha-Estradiol, dihydrotestosterone and progesterone were devoid of activity, suggesting specificity of the estrogen effect. Maximum responses induced by 17 beta-estradiol (5 min at 10(-10) M) could be abolished to a great extent (84%) by pretreating the cells with verapamil (10 microM) and nitrendipine (1 microM), involving the activation of voltage-dependent Ca2+ channels in the fast increase of rat duodenal calcium uptake by the hormone. Evidence was obtained indicating that the acute estrogen stimulation of enterocyte Ca2+ influx is mediated by the cyclic AMP/PKA pathway. 17 beta-Estradiol rapidly increased cAMP content of rat duodenal cells in parallel to the changes in Ca2+ uptake. In addition, forskolin, dibutyryl cAMP and Sp-cAMPS mimicked and Rp-cAMPS suppressed the prompt 17 beta-estradiol-induced stimulation of Ca2+ influx. These results are consistent with a direct action of estrogens in the enterocyte, presumably a non-genomic one, initiated on the cell surface and resulting in rapid activation of the cAMP pathway and Ca2+ channels, which may be relevant for regulation of intestinal calcium transport.
Picotto
G
G
Departamento de Biologia y Bioquimica, Universidad Nacional del Sur, Bahia Blanca, Argentina.
Massheimer
V
V
Boland
R
R
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D004386:Duodenum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D009568:Nitrendipine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015290:Second Messenger Systems / Q000502:physiology*; D013873:Thionucleotides / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D013873:Thionucleotides; D005576:Colforsin; C016957:adenosine-3',5'-cyclic phosphorothioate; D004958:Estradiol; D003994:Bucladesine; D009568:Nitrendipine; D014700:Verapamil; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D002118:Calcium