Objective:To further explore the regulatory role of the spermatic nerves in spermatogenesis by investigating effects of testicular denervation on sexual hormone levels. Methods:Forty-eight adult SD male rats were randomly divided into four groups: sham operated group(SO), superior spermatic nerve-removed group(SSN), inferior spermatic nerve-removed group(ISN) and superior and inferior nerve-removed group(SSN+ISN). Blood samples were obtained from the retro-orbital sinus before operation and on postoperative Day 1, 7, 14, 21, 28. The levels of serum testosterone(T), luteinizing hormone(LH), follicle stimulating hormone (FSH), prolactin(PRL) and estrogen(E2) were measured by RIA. Results:Serum testosterone levels dramatically decreased(P < 0.05) in all groups on postoperative Day 1, and on Day 7. The T levels of SO group returned to normal,while those of the denervated rats did not despite some increase(P < 0.05). From 14 Day on, testosterone concentrations underwent progressive decline in the denervated groups(P < 0.05), with those of SSN+ISN group significantly lower than SSN group or ISN group(P < 0.05). Serum LH concentrations were markedly elevated(P < 0.05) in all rats one day after surgery. One week later,the LH values of SO group dropped to the preoperative levels, whereas those of the denervated groups continuously increased and the LH levels of SSN+ISN group were higher than SSN group or ISN group(P < 0.05). A pronounced rise of plasma FSH were detected in all groups one day following operation(P < 0.05) and decline to the normal range occurred on Day 7. Testicular denervation also resulted in a striking rise of serum PRL(P < 0.05) and a sharp drop of E2(P < 0.05). Conclusion:The spermatic nerves may exert its modulatory effects on spermatogenesis partly via regulating sexual hormone levels.