Advantages of pulsatile hormone treatment for assessing hormone-induced gene expression by cultured rat Sertoli cells

In response to various hormonal (follicle-stimulating hormone [FSH] and testosterone [T]) and biochemical inputs, testicular Sertoli cells (Sc) produce factors that regulate spermatogenesis. A number of FSH- and T-responsive Sc-specific genes, necessary for spermatogenesis, have been identified to date. However, the hormone-induced in vitro expression pattern of most of these genes is reported to be inconsistent at various time points in primary rat Sc cultures. As a matter of convenience, cultured Sc are constantly exposed to hormones for a few hours to days in the reported literature, although Sc are exposed to pulsatile FSH and T in vivo. The major aim of the present study is to evaluate the advantage, if any, of the in vitro administration of pulsatile hormone (FSH and T in combination) treatment on gene expression of cultured Sc as compared with that of constant hormone treatment. Pulsatile treatment (a 30-min hormonal exposure every 3 h) mimicking the in vivo condition reveals a more prominent effect of hormones in augmenting gene expression as compared with constant treatment. Our results indicate that the expressions of Stem cell factor (Scf, only responsive to FSH), Claudin11 (only responsive to T) and Transferrin (both FSH- and T-responsive) mRNAs are significantly higher at 12 h upon pulsatile treatment than upon constant hormonal treatment. Maximal expression of relevant genes because of pulsatile treatment with hormones suggests that this protocol provides a more suitable premise for assessing hormone-induced gene expression in isolated Sc than one involving constant exposure to hormones.