Ovariectomy modulation of morphine analgesia of neuropathic pain is associated with the change of K(+)-Cl(-) cotransporter 2 protein level in spinal dorsal horn.

Journal: International Journal Of Clinical And Experimental Medicine
Published:
Abstract

Sex differences in opioid analgesia have been confirmed both in clinical and experimental studies. Gonadal hormones (estrogens in particular) have a great role in this process. However, the mechanisms that underlie these sex differences are not very clear. In this study, we used K(+)-Cl(-) cotransporter 2 (KCC2) as a molecule target to investigate the mechanism underlying the phenomenon. Sprague-Dawley rats were randomly assigned to ovariectomy (OVX)+morphine group, OVX+Saline group, sham surgery (OVX-sham)+morphine group and OVX-sham+saline group. All the rats received SNI surgery three weeks after ovariectomy. We used von Frey values as a sign of neuropathic pain. On PO day 14, 1 μg morphine or the vehicle saline was administered intrathecally via a PE-10 catheter formerly implanted. Hindpaw withdrawal threshold was determined before and 30, 60, 90, 120, 150, 180 min after drugs injection. The L4-L5 segments of the spinal cord were removed and immunoblotted for KCC2 protein at the time of 2 and 3 h after drugs administration. We find that ovariectomy can regulate the sensitivity to morphine analgesia of neuropathic pain and KCC2 protein level will change in the spinal dorsal horn.

Authors
Weijun Shen, Liang Shen, Guoqiang Chen, Fen Wang, Cheng Li, Fuqing Lin, Xiaohu Yang, Shukun Fu
Relevant Conditions

Neuralgia, Oophorectomy