Differential effects of follicle-stimulating hormone, insulin, and insulin-like growth factor I on hexose uptake and lactate production by rat Sertoli cells.
The stimulatory effects of follicle-stimulating hormone (FSH), insulin, and insulin-like growth factor I (IGF-I) on lactate production and hexose uptake by Sertoli cells from immature rats were studied. The time-courses and the maximal stimulatory effects of FSH, insulin, and IGF-I on lactate production were virtually identical. When Sertoli cells were incubated in the presence of FSH in combination with insulin or IGF-I (submaximal doses), additive but no pronounced synergistic effects were observed. The stimulatory effects of FSH and insulin were not dependent on the presence of extracellular calcium. 2-Deoxy-D-glucose (2-DOG), an analogue of D-glucose, was used to investigate the hexose transport system of Sertoli cells. Uptake of 2-DOG was linear in time and virtually all of the intracellular 2-DOG was phosphorylated up to 30 min of incubation; 2-DOG uptake was inhibited by cytochalasin B, but not by cytochalasin E. D-glucose, but not D-galactose, appeared to be an effective competitor of 2-DOG uptake. The Km of 2-DOG uptake was not influenced by FSH, insulin, and IGF-I. FSH had no effect on the Vmax of 2-DOG uptake, whereas insulin and IGF-I caused a 30% stimulation of the Vmax. It is concluded that FSH, insulin, and IGF-I stimulate lactate production by cultured Sertoli cells, but that only insulin and IGF-I stimulate hexose transport. The insulin-like effect of FSH on Sertoli cells may principally involve stimulation of glycolytic enzyme activities.
Oonk
R B
RB
Department of Biochemistry, Medical Faculty, Erasmus University Rotterdam, The Netherlands.
Jansen
R
R
Grootegoed
J A
JA
D000818:Animals; D001692:Biological Transport; D003847:Deoxyglucose / Q000378:metabolism; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006601:Hexoses / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007773:Lactates / Q000096:biosynthesis*; D008297:Male; D051381:Rats; D012708:Sertoli Cells / Q000378:metabolism*; D013002:Somatomedins / Q000494:pharmacology*
D006601:Hexoses; D007328:Insulin; D007773:Lactates; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D003847:Deoxyglucose