Transferrin and sulfated glycoprotein-2 messenger ribonucleic acid levels in the testis and isolated Sertoli cells of hypophysectomized rats

Both FSH and testosterone act on Sertoli cells in the testis. It is possible that the action of these hormones on Sertoli cells results in an increased capacity for the cells to carry out their prescribed functions, among which are the synthesis and secretion of specific glycoproteins. Changes in the testicular levels of two specific mRNAs in hypophysectomized hormone-treated rats were determined by solution hybridization to cRNA probes. The mRNAs coding for transferrin and sulfated glycoprotein-2 (SGP-2), both of which are secretion products of Sertoli cells, decreased dramatically in the testis of hypophysectomized rats that were maintained for 20 days untreated with hormones. If hypophysectomy was done to rats at 20 days of age, daily injections for a subsequent 20 days with FSH or FSH in combination with testosterone partially maintained both transferrin and SGP-2 mRNA levels. Testosterone alone was ineffective in 20-day-old rats. In contrast, if hypophysectomy was performed on 40-day-old rats, daily injections of testosterone alone or in combination with FSH were most effective in maintaining higher levels of the specific mRNAs. When the Sertoli cells from rats hypophysectomized at 20 days of age were placed in cell culture, FSH again was most effective in the stimulation of transferrin mRNA above control levels. However, when the Sertoli cells from the rats hypophysectomized at 40 days of age were placed in culture, FSH was slightly stimulatory, but testosterone had no effect on the transferrin mRNA levels. Neither FSH nor testosterone affected the levels of SGP-2 mRNA in the cultured cells regardless of the age of the animal at the time of hypophysectomy. Additional in vivo studies were done in which the rats were hypophysectomized at 20 days of age, allowed to regress for 17 days, and then injected daily with hormones for 3 days. The levels of transferrin and SGP-2 mRNA in this experiment were stimulated by FSH alone or by a combination of FSH and testosterone to an extent similar to that in the cultured cells. These studies showed that FSH is most important in the younger rats and testosterone is most important in the older rats in the maintenance of specific mRNA levels. In addition, the level of stimulation observed with either hormone is different depending on whether the hormone is given in culture or in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)