EFFECT OF CHLORMADINONE ACETATE-PELLET IMPLANTATION ON THE VOLUME OF PROSTATE, PERIPHERAL-BLOOD LEVELS OF SEX-HORMONES AND SEMEN QUALITY INTHE DOG

Chlormadinone acetate (GS implant(R), CMA) pellet, a synthetic luteal hormone preparation, Was Subcutaneously implanted at 5, 10 and 20 mg/k g in four normal male dogs ranging in age from 3 to 10 years to determ ine the changes in the prostatic volume, peripheral plasma levels of s ex hormones and semen quality. The plasma levels of CMA, LH, testoster one (T) and 5 alpha-dihydrotestosterone (DHT) were measured by radioim munoassay. The prostatic volume was measured by computed tomography. T he semen was collected by digital manipulation. The pellet was removed 26 weeks after implantation. The effects of CMA pellet implantation w ere examined during implantation and until 22 weeks after removal.:The prostatic volume was reduced to 61+/-3 (mean +/-S.E., n=4), 52+/-5 (n =4) and 53+/-9 (n=4)% of the preimplantation volumes in the 5, 10 and 20 mg/kg groups, respectively. The plasma CMA levels in the 10 mg/kg a nd 20 mg/kg groups peaked at 2 weeks, but were gradually decreased. At 22 weeks after removal of the pellet, the prostatic volume returned t o 74-85% of the preimplantation volumes. The plasma LH levels tended t o increase after implantation in all groups. The plasma T and DHT leve ls were slightly decreased in all groups. In the 10 and 20 mg/kg group s, the number of sperm and motility sperm was reduced, and the rate of abnormal sperm increased. These findings indicated that implantation of a CMA-pellet at a dose of 10 mg/kg or more decreases the prostatic volume to 1/2 the original size and retains its effect for a long time , although it depresses gonadal function. The present study suggested that CMA implantation is useful in treating benign prostatic hyperplas ia.