Effects of insulin-like growth factor-I on androgen production by highly purified pubertal and adult rat Leydig cells.
Leydig cells were isolated and purified from adult and midpubertal rats to study the effects of insulin-like growth factor-I (IGF-I) on steroidogenesis. Androgen production, as measured in Leydig cell conditioned culture media, from four different treatment groups (1 = no hormone; 2 = 70 ng/ml IGF-I; 3 = 0.1 ng/ml LH; 4 = 70 ng/ml IGF-I + 0.1 ng/ml LH) were compared daily. After 3 days in culture, the cells were treated with a maximally stimulating dose of luteinizing hormone (LH) (100 ng/ml) for 3 hours. Androgen production was highest in the cells treated with both IGF-I and low concentrations of LH. In the presence of IGF-I, regardless of LH, cells derived from pubertal animals had a greater increase in steroidogenesis during the culture period than did cells from adult animals. Pretreatment with IGF-I prior to maximal LH stimulation induced a greater increase in androgen production in cells from pubertal rats than in cells from adult animals. It is concluded that IGF-I has a direct effect on Leydig cells and may act synergistically with LH to promote androgen synthesis. The greater response in pubertal cells raises the possibility that IGF-I is important in the maturing process of the testis.
Gelber
S J
SJ
Department of Pediatrics, Johns Hopkins University, Baltimore, Maryland.
Hardy
M P
MP
Mendis-Handagama
S M
SM
Casella
S J
SJ
D000375:Aging / Q000378:metabolism*; D000728:Androgens / Q000378:metabolism*; D000818:Animals; D002469:Cell Separation; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007985:Leydig Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000728:Androgens; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone