| Background The reason and mechanism of male infertility have attracted the investigator's attention in recent years. An increasing number of reports have suggested a trend toward decreasing sperm quality in men over the past five decades. Due to the relatively short period of time for this trend to occur, it is believed that decreasing sperm quality is the result of environmental rather than genetic factors. Temperature as an environmental factor brings heat induced male infertility has been attentioned. Several studies have shown that in most mammals, including humans, the testis is always maintained at a lower temperature than that in the abdomen, and exposure of the testis to body temperature or above results in increased death of spermatogenic cells. Mild testicular heating has been established as a safe and reversible approach for suppression of spermatogenesis. In addition, some studies suggest that the one of reasonof infertility with cryptorchidism is spermatogenic cell apoptosis induced by abdomen temperature. Currently, surgical ligation of the vas deferens is the only efficacious male contraceptive method. The high financial cost, surgical risk involved, and relatively high incidence of permanent infertility are some of the inherent disadvantages of this method, hence itslimited use. The search for a self-applied, reliable and reversible method has been intensified in recent years. Thus, safety, efficacy and applicability of thermal manipulation of spermatogenesis as a method of male contraception could either be established or refuted. Futher understanding of the regulation of spermatogenic cell apoptosis may allow new targeted approaches to male contraceptive development and treatment of some forms of male infertility.Objective 1) To determine whether the heat-induced loss of spermatogenic cells in the adult rat occurs via apoptosis. 2) To explore the sensitivety of spermatogenic cells with local testicular heating. 3) To examine the role of Fas and FasL in rat testicular spermatogenic cell apoptosis with local testicular heating.Material and Methods Adult male Sprague-Dawley rats were housed in a standard animal facility under controlled temperature (22℃) and photoperiod(12h:12h), with free access to water and rat chow. The scrotum containing testes were then immersed for 30 min in a thermostatically controlled water bath at 43 ℃. Control rats were treated in the same way, except the testes were immersed in a water bath maintained at 22℃. The rats sacrificed at 0.5, 1,3,6, 10, 25, 50 and 80d after heat exposure and collected samples. The weight of testis was detected and the histology of testis was observed by HE stain; The apoptosis of spermatogenic cells was detected by means of electron microscopy, flow cytometry and TUNEL (TdT-mediated dUDP-X nick end labeling) method; Fas and FasL expression was observed with flow cytometry and immunohistochemistry.Results Rat testicular weight fell beginning at 3 days and reachingminimum values during 10-25 days after heating and it was recover at 50 days post-heating (P<0.01) . But by 80 days following heat treatment testicular weight was almost normal. Histological examination showed that germinal epithelium became thin, the number of spermatogenic cells was decreased, vacuoles were common, many spermatogenic cell nuclei contained highly condensed chromatin and multinucleate cells were appeared. On groups of 10 and 25d, these change were severe. By the day80, germinal epithelium was almost recovered.Spermatogenic cell apoptosis: 1) In all groups of heat treatment, crescent chromatin condensation under nuclear membrane and the apoptotic bodies were detected by electron microscopy. Correspondingly, the features of spermatogenic cell apoptosis were occasional in the control groups. 2) Flow cytometry found that the percentage of cells with sub-haploid was increased in all heat treatment groups compared with respective control group (P<0.01) . Moreover, the change was marked in heat treatment groups of 0.5-6d (controls: 0.5d:2.85... |
PDF Full Text Request