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Effects of Unilateral Castration and Unilateral Cryptorchidism of the Holstein Bull on in Vitro Leydig Cell Response^1,2,

Clemson University, Clemson, SC 29631

³ Reprint Requests: Dept. of Dairy Sci., Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061.

Abstract

The effects of unilateral castration (UC) and induced unilateral cryptorchidism (CR) on in vitro Leydig cell function were determined utilizing 36 Holstein bulls altered at either 3, 6 or 9 mo of age. Testes were removed 11 mo after gonadal manipulation and Leydig cells were dispersed in media containing 0 or 75 ng luteinizing hormone (LH). After incubation for 4 h, testosterone (T) concentration in the media was determined by radioimmunoassay. Leydig cells of UC animals produced greater (P<.001) amounts of T than did Leydig cells of either CR or intact (IN) bulls with either 0 or 75 ng LH. Leydig cell T response was greater (P<.001) in UC animals altered at 3 mo of age than in those altered at 6 or 9 mo of age. In a second experiment using only UC bulls altered at 3 mo of age, similar results were obtained. Leydig cells of UC bulls produced greater (P<.05) amounts of T in vitro, both without LH or in response to 75 ng LH, than did Leydig cells of IN bulls at 10 mo after gonadal manipulation. Results indicate that UC in the bull causes increased Leydig cell capacity for T production in the remaining hypertrophied testis and this effect is greater when UC is performed at 3 mo of age than at 6 or 9 mo of age.

¹ Scientific Contribution No. 1976, South Carolina Agr. Exp. Sta.

² Dept. of Dairy Sci.

⁴ The authors are indebted to G. D. Niswender, Colorado State Univ., Ft. Collins, for testosterone anti-serum, S250 and to the Endocrine Study Section, Bethesda, MD, for NIH-LH-B4 used in this study.