Biopotency of highly purified porcine FSH and human LH on gonadal function

Abstract

ABSTRACT The gonadotrophin preparations that have been used previously to study different aspects of testis function are of limited purity. We have, therefore, purified existing gonadotrophin preparations further. The demonstration of their purity and biological activity are reported as well as their suitability for in-vivo use. After separation of the subunits of the intact hormones by high-performance liquid chromatography followed by analytical sodium dodecylsulphatepolyacrylamide gel electrolphoresis, no contaminating proteins could be detected in either the FSH or LH preparation. After immunoadsorption, contamination by other pituitary hormones (TSH, prolactin, FSH, LH and GH) was found to be less than 0·002% by weight for all the hormones tested. The biological activity of porcine FSH (pFSH) measured in a Steelman–Pohley assay was 150–170 times more potent than the NIH-FSH-P1 reference preparation. The biopotency of human LH (hLH) in the ovarian ascorbic acid depletion test was measured and appeared to be 8100–8300 IU/mg against the 68/40 International Standard. The dose-dependent effects of pFSH and hLH on testis weight and the number of FSH and LH receptors were measured in immature (22-day-old) hypophysectomized rats treated for 7 consecutive days. Treatment with FSH induced a dose-dependent increase in testis weight (threefold) when compared with the control. The concentration and total number of LH receptors were increased (two- to sixfold) in a dose-dependent manner. The number of FSH receptors per testis increased while the number of FSH receptors per mg of protein remained unchanged. Administration of human LH to immature hypophysectomized rats had no effect on either LH or FSH receptors, regardless of the dose administered. The plasma concentration of testosterone measured after seven injections of FSH remained at the level of (0·31 nmol/l) found in saline-injected control rats. After 7 days of treatment with hLH, the plasma concentration of testosterone had increased in a dose-dependent manner (three- to tenfold). These results indicate that the gonadotrophin preparations are both highly purified and retained full biological activity and, therefore, are ideal for in-vivo physiological studies. Journal of Endocrinology (1989) 120, 89–96