Neuroprotective Effects of Testosterone on Regenerating Spinal Cord Motoneurons in Rats

ABSTRACT

Degeneration in the CNS and peripheral nervous system consists of degradation and phagocytosis of axons and their myelin sheath distal to the site of injury. Testosterone is a gonadal sex steroid hormone that plays an important role in CNS development. One of the lesser-known testosterone actions is neuroprotection. In the present study, the authors investigated the neuroprotectective effect of intracerebral ventricular injection of testosterone on the number of spinal motoneurons after sciatic nerve crush. In all, 32 male Wistar rats were divided to 4 groups (control, compression, compression + castration, compression + testosterone injections; n = 8). Four weeks after compression the lumber segments of spinal cord were sampled, processed, sectioned serially, and stained with toluidine blue (pH = 4.65) by using steriological quantitative technique (physical dissector), the number of alpha motoneurons in the right ventral horns of spinal cord were counted and compared between groups. Statistical analyses showed that testosterone injections (1μl icv, 4 times, 1 week interval between injections) significantly (p < .05) reduced neuronal damage. These results indicated that testosterone has an obvious neuroprotective effect on lumbar spinal motoneurons.

Keywords:

• alpha motoneurons
• neuronal degeneration
• sciatic nerve
• testosterone

ACKNOWLEDGMENT

This study was supported by a grant from the Islamic Azad University, Mashhad branch, Iran. The authors are grateful to A. Rahimi and S. Mousavi for invaluable technical assistance.