Effect of chronic spinal cord injury's severity on sperm parameters in rat: correlation with locomotion deficits.

OBJECTIVES: Infertility is one of the major concerns for male patients following spinal cord injury (SCI). Although the severity of the injury has a large impact on extent of infertility, the effect of exact injury extent (with specific affected spinal tracts) on fertility is not studied yet. MATERIALS AND METHODS: In the present study, sperm parameters, locomotion scores, and hormonal changes were evaluated following dorsal one third SCI (1/3 SCI), dorsal two third SCI (2/3 SCI), and complete spinal cord transection (TX) at T8 spinal level in male rats. RESULTS: Sperm count decreased significantly following 1/3 SCI and Tx compered to normal (control and sham). In addition, sperm count decreased significantly in Tx compared to 1/3 SCI and 2/3 SCI. Concerning sperm motility, although, percentage of motile sperms decreased significantly in Tx group in comparison to all other groups, the percentage of rapid progressive motile sperms (RPM) decreased significantly in all SCI groups compared to normal. Meanwhile, locomotion score (BBB-score) showed a significant progressive decrease following SCI compared to normal or within SCI groups. However, there was no significant changes in the serum hormonal and seminal fructose concentrations following SCI compared to normal. CONCLUSIONS: These results show that understanding the extent of SCI, the affected spinal tracts, and the resultant locomotion deficits may help to predict the deficits in sperm parameters and hence fertility potentials.

Severing the ventral funiculus in chronic spinal cord injury has the most deteriorating effect on spermatogenesis in rats.

Sexual dysfunction, following spinal cord injury (SCI), is highly dependent on the extent of injury. SCI disrupts the supraspinal innervation of the reproductive organs; resulting in structural and functional deficits. Relating the extent of SCI to these changes could eventually improve diagnoses and treatment planning of sexual dysfunction following SCI. In the present study, following chronic SCI of different severities (1/3 dorsal SCI (1/3 SCI), 2/3 dorsal SCI (2/3 SCI), and complete transection (Tx)) at T8 spinal level, histological changes of seminiferous tubules parameters in testis were examined. The diameter of seminiferous tubules (DST) and epithelial height of seminiferous tubules (HST) were significantly decreased in all SCI groups compared to control and sham. In addition, DST in 2/3 SCI and Tx groups and HST in Tx group were significantly decreased in comparison with 1/3 SCI animals. Nonetheless, the diameter of seminiferous tubules' lumen decreased significantly in 2/3 SCI and Tx compared to control, sham, and 1/3 SCI groups. Concerning cellular component, the number of spermatocytes and spermatids layers significantly decreased in both 1/3 and 2/3 SCI in comparison to normal. However, Tx had the most prominent deteriorating effect on these layers; indicating impairment in the process of spermatogenesis. These results show that the spinal tracts are part of the neural circuitries innervating the testis and responsible for their structural support. These tracts are mainly distributed between the lateral and ventral funiculi at T8 spinal level. Consequently, sparing ventral funiculi in the SCI prevents the severe decline in spermatogenesis.