Li, KC (reprint author), Chinese Acad Sci, Inst Neurosci, Beijing 100864, Peoples R China,firstname.lastname@example.org
Background: It has been shown that estrogen is synthesized in the spinal dorsal horn and plays a role in modulating pain transmission. One of the estrogen receptor (ER) subtypes, estrogen receptor alpha (ER alpha), is expressed in the spinal laminae I-V, including substantia gelatinosa (SG, lamina II). However, it is unclear how ERs are involved in the modulation of nociceptive transmission. Results: In the present study, a selective ER alpha antagonist, methyl-piperidino-pyrazole (MPP), was used to test the potential functional roles of spinal ER alpha in the nociceptive transmission. Using the whole-cell patch-clamp technique, we examined the effects of MPP on SG neurons in the dorsal root-attached spinal cord slice prepared from adult rats. We found that MPP increased glutamatergic excitatory postsynaptic currents (EPSCs) evoked by the stimulation of either A delta- or C-afferent fibers. Further studies showed that MPP treatment dose-dependently increased spontaneous EPSCs frequency in SG neurons, while not affecting the amplitude. In addition, the PKC was involved in the MPP-induced enhancement of synaptic transmission. Conclusions: These results suggest that the selective ER alpha antagonist MPP pre-synaptically facilitates the excitatory synaptic transmission to SG neurons. The nociceptive transmission evoked by A delta- and C-fiber stimulation could be potentiated by blocking ER alpha in the spinal neurons. Thus, the spinal estrogen may negatively regulate the nociceptive transmission through the activation of ER alpha.
Zhong, Yan-Qing; Li, Kai-Cheng; Zhang, Xu.Potentiation of excitatory transmission in substantia gelatinosa neurons of rat spinal cord by inhibition of estrogen receptor alpha,MOLECULAR PAIN,2010,6():92-92