Electrophysiological and Neurochemical Studies of the Vestibular Nuclei of the Rat in Relation to the Cerebellum

 
 
 
 

Electrophysiological and Neurochemical Studies of the Vestibular Nuclei of the Rat in Relation to the Cerebellum

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dc.contributor.advisor Godfrey, Ph.D., Donald A. en_US
dc.contributor.author Sun, Yizhe en_US
dc.date.accessioned 2008-07-10T16:38:09Z
dc.date.available 2008-07-10T16:38:09Z
dc.date.created 2006 en_US
dc.date.issued 2008-07-10T16:38:09Z
dc.identifier.uri http://rave.ohiolink.edu/etdc/view?acc_num=mco1140206345 en_US
dc.identifier.uri http://hdl.handle.net/2374.OX/18091
dc.description We employed extracellular recording from rat brain slices to compare the spontaneous activity in the four major nuclei of the vestibular nuclear complex (VNC), and to investigate the roles of acetylcholine (Ach) and g-aminobutyric acid (GABA) in the VNC of normal rats. We also employed microdissection of freeze-dried brain sections combined with HPLC analysis to measure the distributions of amino acid neurotransmitters in the VNC of normal rats. Next, we used these same techniques, combined with surgical transections of the inferior cerebellar peduncle (ICP), to study changes of amino acid distributions and GABA pharmacology after loss of the major cerebellar input to the VNC. The mapping study of spontaneously active neurons in the four major nuclei showed that spontaneous firing was present in all subnuclei of the VNC, with the highest density in the medial vestibular nucleus (MVN) and the lowest in the lateral vestibular nucleus (LVN). Amounts are sufficient, except in the LVN, for pharmacological studies. There were regional differences of spontaneous firing in the MVN. Results with the effects of ACh agonists and antagonists showed that cholinergic effects on spontaneous activity of MVN, spinal vestibular and superior vestibular neurons are mostly through muscarinic receptors. Nevertheless, MVN neurons were also somewhat responsive to nicotine. Effects of subtype-preferential muscarinic antagonists on MVN neurons suggested that the most prominent subtype is M4. Quantitative distributions of 12 amino acids in the VNC were measured in both control rats and in rats with transection of the ICP. After the unilateral cut, concentrations of GABA and glutamate decreased 2 days after surgery in nearly all VNC regions. Glutamate levels completely recovered by 30 days, whereas GABA showed only partial recovery on the lesioned side. The degrees of reduction of GABA and glutamate in different VNC regions varied. Larger losses of GABA and glutamate occurred 7 days after bilateral transections than 7 days after unilateral transections of the ICP. Study of the GABA pharmacology in the MVN of bilaterally lesioned rats showed a higher sensitivity to both GABAA and GABAB agonists than for MVN neurons of control rats, suggesting these receptor subtypes are up-regulated. Responses of MVN neurons to GABA antagonists alone were smaller in lesioned than in control rats. en_US
dc.format application/pdf en_US
dc.format 236p. en_US
dc.rights unrestricted en_US
dc.rights Copyright and permissions information available at the source archive en_US
dc.subject Vestibular Nuclei en_US
dc.subject Brain Slice en_US
dc.subject GABA en_US
dc.subject Acetylcholine en_US
dc.subject Cerebellar Peduncle en_US
dc.title Electrophysiological and Neurochemical Studies of the Vestibular Nuclei of the Rat in Relation to the Cerebellum en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name PhD en_US
dc.degree.level doctoral en_US
dc.degree.discipline Graduate Studies en_US
dc.degree.grantor University of Toledo Health Science Campus en_US
dc.contributor.publisher University of Toledo Health Science Campus / OhioLINK en_US

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