Muscarinic presynaptic inhibition of neostriatal glutamatergic afferents is mediated by Q-type Ca2+ channels

摘要: Abstract Cholinergic presynaptic inhibition was investigated on neostriatal glutamatergic transmission. Paired pulse facilitation (PPF) of orthodromic population spikes (PS) were used to construct a concentration-response relationship for muscarine inhibition. Muscarine had an effect proportional its extracellular concentration with EC50 (mean ± standard estimation error) of: 2.5 1.5 nM, and maximal (saturation) 245 16 %. Several peptidic toxins against some voltage-gated Ca2+-channels increased PPF indicating that the they block participate in transmitter release. However, neither 1 μM ω-conotoxin GVIA, specific blocker N-type Ca2+-channels, nor 10–30 nM ω-agatoxinTK, selective P-type able occlude muscarine’s Nevertheless, 100–400 ω-agatoxinTK occluded action dose-dependent manner. These results are consistent Q-type mediating muscarinic afferents.