Uential UVD procedure, involving intratympanic sodium arsanilate injections (i.e., one

Uential UVD procedure, involving intratympanic sodium arsanilate injections (i.e., one ear, followed several weeks later by the other ear), and observed a significant increase in the NMDA receptor Bmax and a decrease in Kd in the hippocampus. This sequential UVD procedure has the advantage of buy EXEL-2880 relevance to paroxysmal vestibular disorders in humans in which the right vestibular labyrinth malfunctions, and then the left, or vice versa, e.g. some types of Meniere’s disease [8]. The aim of the present study was to investigate the expression of several glutamate receptor 11967625 subunits and calmodulin kinase IIa (CaMKIIa) in the CA1, CA2/3 and dentate gyrus (DG) subregions of the hippocampus, at various time points following BVD, using western blotting. For the NMDA receptor, the NR1 subunit was analysed because it is necessary for NMDA receptor function, binding the co-agonist, glycine, while the NR2 subunit binds glutamate [18]. The NR2A and NR2B subunits were measured because they have an important impact on the receptor’s channel conductance, ligand affinity and sensitivity to Mg2+ [19?2]. For the AMPA receptor, all 4 GluR subunits were measured, GluR1 and GluR2 being the most commonly expressed in the hippocampus, with lower levels of GluR3 and GluR4 [23?5]. There is a close relationship between CaMKII and NMDA and AMPA receptor subunits. CaMKII binds to the NR1 and NR2B subunits, and phosphorylates AMPA receptors, thereby altering their channel conductance [26,27]. Furthermore, activation of NMDA receptors increases the activation of CaMKII, leading to autophosphorylation [28]. Therefore, we also measured CaMKIIa and phosphorylated CaMKIIa (pCaMKIIa) expression in the same hippocampal subregions.and 1 week time points; n = 7 for the BVD group and 6 for the sham group for the 1 month time point; and n = 14 for the BVD group and 12 for the sham group at the 6 month time point, making a total of 81 animals). For the 6 month time point, BVD or sham animals were divided into those with or without spatial forced alternation in T maze training (n = 7 or 6 for each group, respectively), to determine whether spatial learning experience had any effect on hippocampal glutamate receptor expression. The animals in this group have previously been reported to exhibit spatial memory deficits [5]. Animals were maintained on a 12:12 h light:dark cycle at 22uC and housed in individual cages.Ethics StatementAll procedures were carried out in accordance with the regulations of the University of Otago Committee on Ethics in the Care and Use of Laboratory Animals and were approved by that Committee.SurgeryThe animals were anaesthetized using 300 mg/kg fentanyl citrate (i.p.) and 300 mg/kg medetomidine hydrochloride (i.p.) and BVD surgery was performed under microscopic control as detailed previously [4]. Briefly, a retro-auricular approach was used to expose the tympanic bulla. Once exposed, the malleus and incus were removed, the stapedial artery was cauterized; and the horizontal and anterior semicircular canal ampullae and the saccule and utricle were drilled open and their contents aspirated. The sham surgery involved exposing the temporal bone and removing the tympanic membrane without producing a vestibular lesion. Finally, the temporal bone was sealed using dental cement. After the surgical margins had been sutured, a postoperative analgesic, carprofen (5 mg/kg, s.c.), was administered. Previous studies have confirmed, using temporal bone histology, that this.