The effects of testosterone on the response of growth hormone secretion in cultured rat pituitary cells

ABSTRACT

The effects of testosterone on the pituitary growth hormone (GH) response directly and to hypothalamic growth hormone-releasing hormone (GHRH) were evaluated in vitro using a male pituitary cell monolayer culture system. Wistar male rats were gonadectomized at 22 days of age, and 21 days later their anterior pituitaries were removed and trypsinized for cell dispersion. Testosterone 0, 0.1, 1.0, 10.0 nM was added to the medium for 1 day and GH amounts in media were measured. In another experiment, testosterone 1, 0.1, 1.0, 5.0, 10,0 nM was added to the medioum for 3 days, and subsequently 5 nM GHRH was added for 1 day, thereafter GH amounts in media were measured. The results were as follows 1) The increase of GH response after testosterone administration to the cultured rat pituitary cell was not significant. 2) The rat pituitary cell response to GHRH was augmented after pretreatment with testosterone. These results are suggested that testosterone has no direct effect on GH secretion, but by increasing the pituitary cell response to GHRH, contributes to the regulation of GH secretion in vitro.