5-HT2A receptor mediates the ventrolateral orbital cortex-evoked antiallodynia in a neuropathic pain model of rats:A possible presynaptic facilitatory effect
会议名称：《中国生理学会第23届全国会员代表大会暨生理学学术大会》
会议日期：2010年
学科分类：1001[医学-基础医学(可授医学、理学学位)] 100104[医学-病理学与病理生理学] 10[医学]
基 金：supported by the National Natural Science Foundation of China(No.30700222 30800334)
摘 要：Previous studies have indicated that the ventrolateral orbital cortex(VLO),as a high center,is involved in an endogenous analgesic system consisting of a spinal cord-thalamic nucleus submedius-VLO-periaqueductal gray(PAG)-spinal cord *** study has showed that 5-HT receptor is involved in the VLO mediated descending antinociception in the tail flick ***,it is unknown,under neuropathic pain state,whether the VLO 5-HT receptor is also *** the 5-HT receptor is an excitatory G-protein coupled receptor and is distributed not only in the postsynaptic neurons,but also in presynaptic neurons or ***,we suppose that activation of 5-HT receptor induced anti-neuropathic pain in VLO may be produced,except for by postsynaptic direct activation of the VLO neurons projecting to PAG,also probably through a presynaptic facilitatory effect on the excitatory glutamate synapse transmission,leading to activation of the VLO-PAG brainstem descending inhibitory system and depression of the nociceptive inputs at the spinal *** provide support for this hypothesis,the current study was designed to examine whether 5-HT receptor activation-induced anti-allodynia could be blocked by glutamate receptor antagonist and enhanced by its *** withdrawal threshold(PWT) as an index of nociceptive response was measured in response to mechanical stimulation(von Frey filaments) in the spared nerve injury(SNI) *** effect of microinjection of drugs into the VLO on the PWT was *** results showed that microinjection of DOI(2,4,8,16 nmol/0.5μL),a selective 5-HT receptor agonist,into VLO attenuated SNI-induced mechanical allodynia in a dose-dependent *** effect was completely blocked by the selective 5-HT receptor antagonist ketanserin tartrate salt(10 nmol/0.5μL) or significantly attenuated by premicroinjection of a non-selective glutamate receptor antagonist kynurenic acid(KA,2 nmol/0.5μL) into VLO.A small dose(25 nmol/0.5μL) of gl