The function of oestradiol and its receptor in the rat testis

The testis consists of 2 different tissues i.e. the interstitial tissue, which is the site of steroidogenesis, and seminiferous tubules where spermatogenesis occurs. Testosterone production takes place in the Leydig cells of the interstitial tissue and is under the influence of the tropic hormone LH. The action of LH is initiated by interaction with specific receptors located on the cell membrane of the interstitial cells. Binding to the receptor leads to a stimulation of cAMP production and this in turn leads to an activation of cAMP dependent protein kinases. The obligatory function of cAMP in the stimulation of testosterone production can be questioned since cAMP production is undetectable with doses of LH which result in maximum steroidogenesis. The role of protein kinase seems more clear since a correlation exists between protein kinase activation and stimulation of testosterone production. The involvement of protein synthesis in the mechanism of action of LH was confirmed by the discovery of the synthesis of a specific protein after LH stimulation and the inhibition of testosterone production by protein synthesis inhibitors.