The Effect of the Administration of a LHRH Analog and the Local Testicular Irradiation on the Rat Prostate

Shin, Ki Yong; Woo, Young Nam

Abstract

Recently LHRH analog has been interested in the endocrine management of metastatic prostatic. cancer. But the effect of LHRH analog therapy on the prostate has not been previously documented definitely. And the initial flare phenomenon may be developed after initiation of LHRH analog therapy, but the definite method to block this phenomenon has not been introduced. To assess the effect of LHRH analog administration on the prostate, The author observed the weight and histopathologic changes of rat prostate during the administration of a potent LHRH analog (leuprolide acetate) for 6 weeks. And the author intended to present a possible method to block the initial flare phenomenon by observation of the weight and histopathologic changes of rat prostate after local testicular irradiation with a minimal dose(500 rad) producing Leydig cell dysfunction. The following results were obtained: 1. The prostate weight in control group was progressively increased during experimental periods At 0 day, 3 weeks and 6 weeks of experimental period, the prostate weights were 0.44gm, 0 58gm and 0.64gm respectively. 2. The prostate weight in leuprolide treated group was significantly decreased at 3 weeks(0.40+/-0.02gm) and 6 weeks (0.30+/-0.04gm) of administration in contrast to the age-matched control group (p<0.05). 3. The prostate weight in testicular irradiation group was significantly decreased at 3 weeks(0.44+/-0.04gm) and 6 weeks(0.42+/-0.02gm) after irradiation in contrast to the age-matched control group(p<0.05). But its change was less prominent than leuprolide treated group. 4. The pathologic change of prostate after leuprolide administration was the vacuolization of acinar cells. The vacuolization was noticed at 2 weeks of administration and pro gressively increased to the 6 weeks. 5. The pathologic change of prostate after testicular irradiation was the progressively increased vacuolization of acinar cells during experimental periods, but its change was less significant than leuprolide treated group. These results suggest that LHRH analog develops the progressive vacuolization of acinar cells, causing the regression of acinar cells and prostatic atrophy as well as the possible inhibition of normal prostatic growth and that local testicular irradiation prior to LHRH analog therapy may be a possible method to block the initial flare phenomenon.