Referenced in: none

Automatically associated channels: SK3

Title: Lowering glucose level elevates [Ca2+]i in hypothalamic arcuate nucleus NPY neurons through P/Q-type Ca2+ channel activation and GSK3β inhibition.

Authors: Yu Chen, Jun Zhou, Na Xie, Chao Huang, Jun-qi Zhang, Zhuang-li Hu, Lan Ni, You Jin, Fang Wang, Jian-Guo Chen, Li-Hong Long

Journal, date & volume: Acta Pharmacol. Sin., 2012 May , 33, 594-605

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/22504905

Abstract
To identify the mechanisms underlying the elevation of intracellular Ca(2+) level ([Ca(2+)](i)) induced by lowering extracellular glucose in rat hypothalamic arcuate nucleus NPY neurons.Primary cultures of hypothalamic arcuate nucleus (ARC) neurons were prepared from Sprague-Dawley rats. NPY neurons were identified with immunocytochemical method. [Ca(2+)](i) was measured using fura-2 AM. Ca(2+) current was recorded using whole-cell patch clamp recording. AMPK and GSK3β levels were measured using Western blot assay.Lowering glucose level in the medium (from 10 to 1 mmol/L) induced a transient elevation of [Ca(2+)](i) in ARC neurons, but not in hippocampal and cortical neurons. The low-glucose induced elevation of [Ca(2+)](i) in ARC neurons depended on extracellular Ca(2+), and was blocked by P/Q-type Ca(2+)channel blocker ω-agatoxin TK (100 nmol/L), but not by L-type Ca(2+) channel blocker nifedipine (10 μmol/L) or N-type Ca(2+)channel blocker ω-conotoxin GVIA (300 nmol/L). Lowering glucose level increased the peak amplitude of high voltage-activated Ca(2+) current in ARC neurons. The low-glucose induced elevation of [Ca(2+)](i) in ARC neurons was blocked by the AMPK inhibitor compound C (20 μmol/L), and enhanced by the GSK3β inhibitor LiCl (10 mmol/L). Moreover, lowering glucose level induced the phosphorylation of AMPK and GSK3β, which was inhibited by compound C (20 μmol/L).Lowering glucose level enhances the activity of P/Q type Ca(2+)channels and elevates [Ca(2+)](i) level in hypothalamic arcuate nucleus neurons via inhibition of GSK3β.