Involvement Of Potassium Channels Inhibitory Role Of Galanin On Neonatal Rat Locus Coeruleus Neurons

ObjectiveTo explore the effect of galanin?GAL?on locus coeruleus?LC?neurons from neonatal rat and its potassium channel mechanisms.MethodsBrain slices from neonatal rats were prepared and the resting membrane potential and spontaneous action potential of LC neurons was recorded with whole cell patch-clamp configuration.GAL,AR-M1896 and potassium channel blockers were bath applied with different concentration.ResultsBath application GAL induced hyperpolarization and inhibited firing rate of LC neurons.However,AR-M1896?a selective GalR2 agonist?did not induce significant effect on LC neurons,only at very high concentration it induced slight hyperpolarization and reduced firing rate.The inhibitory effect of GAL was partially blocked by TEA?an antagonist of voltage-dependent potassium channel?and significantly blocked by BaCl₂?an antagonist of inward-rectifying potassium channels?and TPQ?a high selective blocker of GIRK channels?,while other potassium channels blockers such as Glybenclamide?ATP-sensitive potassium channel blocker??Charybdotoxin(large-conductance Ca²⁺-activated K⁺ channels blocker)?Apamin(small-conductance Ca²⁺-activated K⁺ channels blocker)failed to block it.ConclusionsGAL inhibits LC neurons from neonatal rats,mainly through GalR1.TEA-sensitive potassium channels and G-protein activated inward rectifying potassium channels,but not ATP-sensitive potassium channel and calcium-activated potassium channel,are involved in this inhibition.