ON THE FORMATION OF TESTOSTERONE BY THE PERFUSED RABBIT TESTIS

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Abstract
The results of this investigation have proven the feasibility of using a perfusion method in vitro to demonstrate testosterone biosynthesis and secretion in the rabbit testis. It has been shown that (i) accumulation of testosterone in the venous effluent of the perfused testis was the result of biosynthesis and secretion of this compound rather than passive leakage from the organ; (ii) integrity of the enzymes involved in testosterone biosynthesis were maintained during perfusion for up to 7 hours; (iii) secretion rate of testosterone in this system was independent of testis size, venous blood flow, and glucose supply to the testis; (iv) both acetate-1-14C and cholesterol-7α-3H were incorporated into testosterone; (v) no solubilizing agents were needed in this preparation for the biotransformation of cholesterol-7α-3H to test.osterone-3H; (vi) addition of human chorionic gonadotrophin (HCG) or interstitial cell stimulating hormone (ICSH) to the perfusate resulted in increased testosterone secretion and alterations in rates of incorporation of acetate-1-14C and cholesterol-7α-3H into testosterone; (vii) slices of rabbit testis produced radioactive testosterone when incubated with cholesterol-7α-3H and acetate-1-14C, and when gonadotrophins were added to such incubations, the specific radioactivity of testosterone-14C increased whereas that of testosterone-3H decreased; and (viii) the interstitial cell stimulating hormone may have its predominant effect in promoting biosynthesis of cholesterol from acetate both in perfused and in slices of rabbit testis.