Leydig cells, hormone action

In addition to the stimulatory actions of LH and hCG on steroidogenesis in Leydig cells and ovarian cells, these hormones also cause a refractoriness or desensitization of that same steroidogenic response. This may involve a loss of LH receptors (down regulation), an uncoupling of the LH receptor from the adenylate cyclase, an increase in the metabolism of cyclic AMP due to an increased phosphodiesterase activity and a decrease in the activities in some of the enzymes in the pathways of steroidogenesis (see Ref. 69 for other references). 

Sharpe RM (1982) Cellular aspects of the inhibitory actions of LHRH on the ovary and testis. J Reprod Fert 64 517-527 Sharpe RM, Fraser HM (1980) Leydig cell receptors for luteinizing hormone-releasing hormone and its agonists and their... 

Both LH and FSH influence the action of the testis. LH stimulates the Leydig (interstitial) cells to produce testosterone, the hormone responsible for the development of the male sexual characteristics. FSH stimulates spermatogenesis by its action on the Sertoli cells. 

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