The Actions of Insulin-Like Growth Factors I and II on Cultured Sertoli Cells*

Abstract

Cultured Sertoli cells prepared from young rats (13 days old) showed increased incorporation of [3H]thymidine into DNA, increased production of lactate, and increased incorporation of [3H]leucine into protein in response to micromolar concentrations of insulin and nanomolar concentrations of insulin-like growth factor II (IGF-II). The first of these responses was also seen with nanomolar concentrations of IGF-I. Receptor affinity labeling studies using Sertoli cell membranes and whole Sertoli cells showed that these cells possess abundant growth factor receptors of type I (mol wt, 350,000) that show high affinity for IGF-I, moderate affinity for IGF-II, and low affinity for insulin. Sertoli cell membranes also show abundant growth factor receptors of type II (mol wt, 230,000) that show high affinity for IGF-II, moderate affinity for IGF-I, and no detectable affinity for insulin. Moreover, the responses of the Sertoli cell to insulin were observed at concentrations of 100 nM or higher, whereas insulin receptors are known to be saturated by insulin at concentrations of 10 nM or less. It is, therefore, concluded that Sertoli cells possess receptors for IGF-I and that the responses observed to insulin may result from binding of these hormones to receptors for IGF-I.

Thyroid hormone and retinoic acid induce the synthesis of insulin-like growth factor-binding protein-4 in prepubertal pig sertoli cells

“…Within the testis the Sertoli cell has been proposed to be a site of IGF-I production (39), reception (40) and action (41,42) as well as of IGFBP generation (43). The intratesticular IGF system appears to be under a complex regulation by endocrine and paracrine factors (16) not fully understood.…”

Differentiating effects of somatomedin-C/insulin-like growth factor I and insulin on Leydig and Sertoli cell functions

“…8) (Lin et al, 1986a, b) in rat Leydig cells. The presence of Sm-C/IGF-I receptors in immature rat Sertoli cells has also been reported (Borland et al, 1984 ;Oonk and Grootegoed, 1987a,b), but contradictory results were obtained concerning insulin receptors. Borland et al (1984) could not demonstrate such receptors in immature cultured rat Sertoli cells and in that model insulin at nanomolar concentrations had no biological effect.…”

Effects of basic fibroblast growth factor and nerve growth factor on lactate production, gamma-glutamyl transpeptidase and aromatase activities in cultured Sertoli cells

“…Lactate production in Sertoli cells has been shown to be under the control of folliclestimulating hormone (FSH) (3), insulin, insulin-like growth factor-I (IGF-I) and IGF-II (4,5), transforming growth factor-b (TGFb) (6) and, more recently, it has been shown that tumor necrosis factor-a (TNFa) is also involved in its production (7). Reduced glutathione is a powerful scavenger of reactive oxygen species and toxic chemicals, which is used by many tissues in the detoxification of electrophilic compounds and cellular protection against oxidative stress (8,9).…”