In vivo regulation of the steroidogenic activity of rat luteal cells by insulin.
The aim of the present study was to determine the long-term effects of insulin treatment on luteal cell function. For this purpose, superovulated prepubertal rats were treated with insulin (group I) or vehicle (group C) for 9 days. Serum progesterone (P4) levels were increased in the insulin-treated group (55 +/- 10 vs 134 +/- 31 ng/ml, P < 0.05). Isolated luteal cells were incubated 3 h, and P4 and 20 alpha-hydroxy-progesterone (20 alpha-OH-P) were measured in the incubation media. A decrease in P4 levels and an increase in 20 alpha-OH-P values [P4 (ng/ml): C = 26.6 +/- 0.3; I = 20 +/- 2; 20 alpha-OH-P (ng/ml): C = 62 +/- 2; I: 120 +/- 7; P < 0.01] were observed in group I. In addition, progestagen (P4 + 20 alpha-OH-P) levels were higher in group I (C = 88 +/- 2; I = 140 +/- 9 ng/ml; P < 0.001). When cytochrome P450scc contents were measured by immunoblotting, a marked increase was observed in luteal cells obtained from group I. LH receptor numbers were decreased in luteal cells isolated from group I (C = 388,834 +/- 14,146; I = 303,057 +/- 13,392 sites/cell; P < 0.001) with a concomitantly diminished LH responsiveness. It is concluded that in vivo treatment of superovulated rats with insulin increases luteal progestagen production by increasing the content of cytochrome P450scc.
Stein
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P
Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina.
Bussmann
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LE
Tesone
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M
D004092:20-alpha-Dihydroprogesterone / Q000032:analysis; D000818:Animals; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000032:analysis; D003338:Corpus Luteum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D007328:Insulin / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000494:pharmacology; D010060:Ovulation; D011374:Progesterone / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011974:Receptors, LH / Q000032:analysis
D007328:Insulin; D011974:Receptors, LH; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D007986:Luteinizing Hormone; D002786:Cholesterol Side-Chain Cleavage Enzyme