alexa The distribution and function of gamma-aminobutyric acid (GABA) in the superior colliculus.
Biomedical Sciences

Biomedical Sciences

Journal of Biomedical Engineering and Medical Devices

Author(s): Okada Y

Abstract Share this page

Abstract Laminer analysis of the distribution of GABA and GAD in the superior colliculus has shown that the distribution pattern of GABA within the SC is similar in rabbit, cat, and guinea pig. The highest levels of GABA were found in the superficial gray layer (SGL), averaging 37-40 mmol/kg dry weight. The GABA concentrations in the deep layers were each only half that of the levels in the SGL. The concentrations of both GABA and GAD in the upper half of SGL are the same as those in the substantia nigra and medial forebrain bundle which have the highest amounts of GABA in the CNS. Denervation studies of the fibers projecting to SGL suggest that the GABA concentrated in the SGL is intrinsic to the layer. The results obtained from immunohistochemical and electron microscopic studies on the localization of GABA neurons corresponds well with the regional distribution pattern of GABA and GAD reported here. However, pharmacological and electrophysiological studies do not necessarily accord well with the GABA distribution studies because they indicate that there are many GABA sensitive neurons in both the SGL and DGL. To investigate the role of GABA in the SGL, the effect of GABA and its agonists and antagonists on neurotransmission in SGL has been studied in SC slices in a perfusion system. Bath applied GABA (100 microM to 1 mM) enhanced the amplitude of postsynaptic field potentials (PSP) in SGL in a dose-dependent fashion and at concentrations above 1 mM it depressed the PSP in a dose-dependent fashion. A similar response pattern was obtained with muscimol (0.1-10 microM excitation; greater than 10 microM inhibition). However (-)-baclofen only inhibited the PSP. Bicuculline (1 microM) shifted the dose-response inhibitory curve of GABA to the right, while the excitatory effect was enhanced. These results indicate that GABA has an excitatory and inhibitory action on neurotransmission in the SGL. The nigro-tectal GABAergic fibers terminate in the intermediate and deep layers of SC. Inhibition of GABAergic activity in the SC causes irrepressible saccades made toward the center of the movement field while GABA activation delays and slows saccadic eye movements. Thus, GABA in the SC plays an important role in the control of eye movements. The same GABAergic projection is also related to the propagation of generalized seizures. There exist collicular neurons which suppress the propagation of seizures.(ABSTRACT TRUNCATED AT 400 WORDS)
This article was published in Prog Brain Res and referenced in Journal of Biomedical Engineering and Medical Devices

Relevant Expert PPTs

Relevant Speaker PPTs

Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri, Food, Aqua and Veterinary Science Journals

Dr. Krish

1-702-714-7001 Extn: 9040

Clinical and Biochemistry Journals

Datta A

1-702-714-7001Extn: 9037

Business & Management Journals


1-702-714-7001Extn: 9042

Chemical Engineering and Chemistry Journals

Gabriel Shaw

1-702-714-7001 Extn: 9040

Earth & Environmental Sciences

Katie Wilson

1-702-714-7001Extn: 9042

Engineering Journals

James Franklin

1-702-714-7001Extn: 9042

General Science and Health care Journals

Andrea Jason

1-702-714-7001Extn: 9043

Genetics and Molecular Biology Journals

Anna Melissa

1-702-714-7001 Extn: 9006

Immunology & Microbiology Journals

David Gorantl

1-702-714-7001Extn: 9014

Informatics Journals

Stephanie Skinner

1-702-714-7001Extn: 9039

Material Sciences Journals

Rachle Green

1-702-714-7001Extn: 9039

Mathematics and Physics Journals

Jim Willison

1-702-714-7001 Extn: 9042

Medical Journals

Nimmi Anna

1-702-714-7001 Extn: 9038

Neuroscience & Psychology Journals

Nathan T

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

John Behannon

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

1-702-714-7001 Extn: 9042

© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version