Changes of Testosterone and Leydig Cells after Transplantation of Newborn Rat Testis Tissues in Castrated Male Rat

Jang, Seok Heun; Woo, Young Nam

Abstract

In this study, in order to obtain physiologic synthesis of testosterone in primary or secondary gonadal insufficiency by Leydig cells transplantation, newborn rat testis tissues were transplantated in castrated male rat. The rats were castrated about 5-6 weeks after birth and were observed for 10 days. At this time, testes were removed from a one-day-old rat and these were transplanted onto the bilateral renal subcapsular lesions of the castrated rats under an operative microscope. Of the 27 rats that were castrated, testis transplantation was possible in 24 rats. The 24 transplanted rats which managed to survive were divided into three groups of 8 rats according to the different time in which blood samplings were to be done, at 2 weeks, 4 weeks, and 6 weeks. After the blood samplings, nephrectomy of the testis transplanted kidney was done. Among the 2 weeks group, one rat died during the experiment and one rat had the transplanted testis unilaterally. Among the 4 weeks and 6 weeks group, 2 rats died from each group, and in the rest 6 rats, the transplanted testes remained in both kidneys. The serum testosterone levels of transplanted group at 2, 4, 6 weeks, the control group of 2 weeks after the castration, and the normal mature rat(about 10 weeks old) showed significant difference(p= 0.001). However, the serum testosterone levels of the transplanted group for 2 weeks and the control group of 2 weeks showed no difference(p= 0.665). The serum testosterone levels of the transplanted group for 4 weeks and 6 weeks did not reach the level of the control group at 4 weeks and 6 weeks(p= 0.020 and 0.030), but their increase was definite. The differences in the Leydig cells of the control group and the transplanted group were observed, and in the control group, the development of the Leydig cells were nonspecific as compared to the somewhat hyperplastic findings in the transplanted group. The morphologic differences of the Leydig cells between these two groups were difficult to be found under an light microscope. In order to classify Leydig cells according to the developmental stage and to understand the functional aspects, the followings are needed to be studied further: the ultrastructural analysis of the Leydig cells; the interactions and changes between Leydig cells and other cells in the testis tissue; measurements of the receptors of the various sex hormones. These studies are thought to be contributory to the in vitro culture of Leydig cells as well as to the clinical applications of the testis transplantation.