Mechanism for baclofen inhibition on quantal glutamate release in spinal dorsal horn neurons
- VernacularTitle:氯苯氨丁酸抑制脊髓背角神经元谷氨酸量子释放的机制
- Author:
Hongyu MA
;
Kun YANG
- Publication Type:Journal Article
- Keywords:
baclofen;
spinal cord;
glutamate;
whole-cell voltage-clamp technique
- From:
Chinese Pharmacological Bulletin
2003;0(09):-
- CountryChina
- Language:Chinese
-
Abstract:
Aim To investigate the inhibition mechanisms of baclofen, a specific GABA B receptor agonist, on quantal glutamate release in the rat spinal dorsal horn neurons.Methods Whole-cell voltage-clamp technique was performed on dorsal horn neurons in rat spinal cord slice to record glutamatergic spontaneous miniature excitatory postsynaptic currents (mEPSCs). Baclofen action on quantal glutamate release was assessed by analyzing the change of mEPESC to baclofen perfusion.Results Baclofen(10 ?mol?L -1,50 s) depressed the frequency, but not amplitude distribution of glutamatergic mEPSCs, indicating baclofen presynaptic depression on glutamate release. The depression on frequency of mEPSCs persisted in Ca 2+-free solution, or in the presence of K + conductance blocker, 4-AP. On the other hand, the depression was occluded by forskolin, an activator of adenylate cyclase, but not protein kinase C (PKC) activator phorbol 12,13-dibutyrate (PDBu). N-ethylmaleimide (NEM), a sulphydryl alkylating agent, which destroys G protein, abolished baclofen depression.Conclusion Not presynaptic K +, Ca 2+ conductance or PKC, but G protein and/or cAMP pathway are involved in the baclofen depression on glutamate release in rat spinal dorsal horn;this depression might contribute to the analgesic action of baclofen at spinal level.
