Role of glycogen synthase kinase-3β in expression and trafficking of GluR1-and GluR2-containing AMPA receptors in spinal dorsal horns of rats with remifentanil-induced hyperalgesia

Abstract

Objective To evaluate the role of glycogen synthase kinase-3β (GSK-3β) in the expression and trafficking of GluR1-and GluR2-containing AMPA receptors in the spinal dorsal horns of rats with remifentanil-induced hyperalgesia.Methods Twenty-four male Sprague-Dawley rats,weighing 240-260 g,aged 2-3 months,were randomly divided into 3 groups (n =8 each) using a random number table:control gourp (group C),remifentanil group (group R),and remifentanil + TDZD-8 (GSK-3β inhibitor) group (group R + T).In group R,remifentanil was infused intravenously at 1.0 μg· kg-1 ·min-1 for 1 h.In group R + T,TDZD-8 1 mg/kg was injected intravenously and then remifentanil was infused intravenously at 1.0 μg· kg-1 · min-1 for 1 h.In group C,normal saline was infused intravenously at 0.1 ml· kg-1 · min-1 for 1 h.Mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 24 h before remifentanil infusion and 2,6,24 and 48 h after remifentanil infusion.The rats were sacrificed after the last behavioral test,and L4.6 segments of the spinal cord were removed to determine the expression of AMPA receptor GluR1 and GluR2 in membrane and total protein in the spinal dorsal horn by Western blot.The ratio of GluR1 expression to GluR2 expression (GluR1/GluR2) in membrane protein was calculated.Results Compared with group C,MWT was significantly decreased,TWL was shortened,the expression of GluR1 in membrane and total protein was up-regualted,the expression of GluR2 in membrane and total protein was down-regulated,and GluR1/GluR2 in membrane protein was increased in group R.Compared with group R,MWT was significantly increased,TWL was prolonged,the expression of GluR1 in membrane and total protein was down-regulated,the expression of GluR2 in membrane and total protein was upregulated,and GluR1/GluR2 in membrane protein was decreased in group R + T.Conclusion GSK-3β mediates up-regulated expression and insertion of GluR1-containing AMPA receptors and down-regulated expression and internalization of GluR2-containing AMPA receptors in the spinal dorsal horns of rats with remifentanil-induced hyperalgesia. Key words: Glycogen synthesis kinase 3 ; Receptors, AMPA ; Piperidines ; Hyperalgesia ; Spinal cord