Efeito do 17β-estradiol na performance locomotora de ratas submetidas à lesão medular por compressão

Abstract

Traumatic spinal cord injury promotes rapid cell death at the lesion epicenter and triggers a series of vascular, cellular and biochemical events, known as secondary damage, which culminate in more cell death, amplifying the injury and tissue dysfunction. The 17β-estradiol (E2) is an endogenous steroid hormone produced primarily by the gonads that has demonstrated neuroprotective effect in vitro and in vivo in several diseases and trauma to the central nervous system (CNS). E2 has shown multiple neuroprotective effects after spinal cord injury by modulating many secondary damage, such as: inflammation, apoptosis, oxidative stress and vascular changes. Accordingly, the aim of this study was to assess whether, acutely, the E2 promotes locomotor recovery in ovariectomized rats subjected to spinal cord compression injury. In the present study, female Wistar rats were subjected to bilateral ovariectomy (OVX) and after one week spinal cord injury was induced by inflation of a embolectomy catheter balloon (Fogarty 2F) with 15μl of saline into the epidural space between T8 and T9 vertebrae for 5 minutes. Fifteen minutes after spinal cord injury surgery a single dose of 100 μg/Kg of E2 diluted in oil (OVX+E2 group) or oil vehicle alone (OVX+oil group) was administered subcutaneously. Some of the animals were subjected to OVX and after a week was performed only spinal laminectomy (OVX+sham group). The locomotor performance of the animals was assessed using the BBB test for 14 days and it was detected significant improvement in locomotor recovery in OVX+E2 group compared to OVX+oil group at 10 and 14 days after spinal cord injury. To verify that better locomotor ability of animals treated with E2 is related with the least amount of damage to the spinal cord tissue, the cross-sections of the histopathological analysis of spinal cord tissue of these animals was performed. The histopathological evaluation detected that the OVX+E2 group showed significantly less tissue damage under the aspects of length, width and area of the lesion compared to OVX+oil group. Accordingly, the results suggest that E2 is able to promote locomotor recovery after a mild compression injury to the spinal cord, and this effect is associated with a reduction of the damage to the spinal cord tissue, supporting the hypothesis that E2 is a neuroprotective hormone