Kir6.2 knockout alters neurotransmitter release in mouse striatum: An in vivo microdialysis study

ATP-sensitive potassium (K-ATP) channels have been demonstrated to play important roles in the brain. In the present study, Kir6.2 knockout (Kir6.2 −/−) mice were used to examine the contribution of Kir6.2-containing K-ATP channels to the regulation of neurotransmitter release via in vivo microdialysis studies. The results showed that the extracellular levels of monoamine and amino acid neurotransmitters in Kir6.2 −/− mouse striatum were similar to those in Kir6.2 +/+ mice under basal conditions. After high K + (100 mM) perfusion, the extracellular levels of DA and amino acids were increased in both genotypes. These increases, however, were significantly lower in Kir6.2 −/− mice than those in Kir6.2 +/+ mice. Extracellular levels of 3,4-dihydroxyphenylacetic acid (DOPAC), a major metabolite of DA, were increased in Kir6.2 −/− mice but decreased in Kir6.2 +/+ mice in response to high K + stimulus. The releases of 4-hydroxy-3-methoxy-phenylacetic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were attenuated to a similar extent in both mouse genotypes. Taken together, this study provides direct in vivo evidence that Kir6.2-containing K-ATP channels play regulatory roles in neurotransmitter release in the striatum.