title: The effects of protein kinase C and calmodulin kinase II inhibitors on vestibular compensation in the guinea pig.
abstract: Previous studies have demonstrated that vestibular compensation, the process of behavioural recovery which occurs following unilateral deafferentation of the vestibular labyrinth (UVD), is correlated with changes in in vitro phosphorylation of various protein substrates in the brainstem vestibular nucleus complex (VNC). The aim of the present study was to investigate the possible causal relationship between protein kinase activity and the induction of the vestibular compensation process, by delivering inhibitors of protein kinase C (PKC) or Ca(2+)/calmodulin-dependent kinase II (CaMKII) into the ipsilateral VNC at the time of the UVD and determining their effects on three static symptoms of UVD, spontaneous nystagmus (SN), yaw head tilt (YHT) and roll head tilt (RHT) in guinea pigs. Infusion of the PKC inhibitor, 3-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrr ole-2,5-dione, HCl (bisindolylmaleimide I, HCl/GF 109203X, HCl) ('Bis I'), at a concentration of 5 or 50 microM, significantly increased SN frequency at the earliest time points (6 and 8 h post-UVD) compared to vehicle controls and the less selective analogue, 2,3-bis(1H-indol-3-yl)-N-methylmaleimide (bisindolylmaleimide V) ('Bis V'). However, the compensation of YHT and RHT was unaffected by the PKC inhibitor. By contrast, the cell-permeable CaMKII inhibitor, myristoylated autocamtide-2 related inhibitory peptide (N-Myr-Lys-Lys-Ala-Leu-Arg-Arg-Gln-Glu-Ala-Val-Asp-Ala-Leu-OH) ('myr-AIP') or the cell-impermeable analogue, autocamtide-2 related inhibitory peptide (N-Lys-Lys-Ala-Leu-Arg-Arg-Cln-Glu-Ala-Val-Asp-Ala-Leu-OH) ('AIP'), failed to alter the compensation of SN, YHT or RHT at any dose compared to vehicle controls. These results implicate PKC-, but not CaMKII-, signal transduction pathways in the initiation of SN compensation in guinea pig.
authors.affiliation: Vestibular Research Group, Department of Pharmacology, School of Medical Sciences, University of Otago Medical School and Neuroscience Research Centre, University of Otago, Dunedin, New Zealand.
authors.forename: A J
authors.initials: AJ
authors.lastname: Sansom
authors.forename: P F
authors.initials: PF
authors.lastname: Smith
authors.forename: C L
authors.initials: CL
authors.lastname: Darlington
authors.forename: R
authors.initials: R
authors.lastname: Laverty
mesh_terms: D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D007758:Ear, Inner / Q000293:injuries; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009760:Nystagmus, Physiologic / Q000187:drug effects* / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D014726:Vestibular Nuclei / Q000187:drug effects* / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases