Testicular Phospholipids: I. Action of Follicle-Stimulating Hormone (FSH) Upon the Biosynthesis of Phospholipids by Rat Testis

FSH stimulates the synthesis of testicular phospholipids when administered in vivo to hypophysectomized adult rats. The phospholipids involved in this response include sphingomyelin, phosphatidyl choline and phosphatidyl ethanolamine. Stimulation was observed by measuring total phospholipid content of the testis and by incorporation of 32P, choline-3H or ethanolamine-3H administered within 4 hr of death. ICSH exerts a similar effect on the synthesis of phospholipids by the testis. However, when FSH was treated with urea in such a manner as to destroy ICSH activity, FSH was still capable of stimulating phospholipid synthesis to approximately the same extent as untreated FSH. It was also observed that the action of FSH (whether urea-treated or not) was confined to the phospholipids of the tubules. Reasons are given for believing that the action of FSH upon the synthesis of testicular phospholipids leads to a general growth of the testis and does not produce early and selective stimulation of the synthesis of phospholipids such as would be expected if the new phospholipids were important in producing the subsequent changes leading to increased mass of the testis. However, since the germinal epithelium is composed of numerous types of cells, further investigation will be necessary to confirm this suggestion. (Endocrinology86: 18, 1970)