University:
Kentucky State University
Course:
BIO 303 | Human Physiology
Academic year:

2021
Views:

338

Pages:

14
Author:

rehinhea0c

Fast Neurotransmitteres Glutamate (L-glutamic acid) • Main excitatory neurotransmitter in the mammalian CNS • 95% of excitatory synapses in the brain are glutamatergic • Precursor for the GABA (major inhibitory neurotransmitter) Fast synaptic transmission Slow synaptic transmission Kainate Ca++ NMDA presynaptic Na+ Kainate AMPA Kainate 95% of excitatory synapses in the brain are glutamatergic postsynaptic The Glutamate Synapse Interconversion of glutamate to glutamine Note – significant Glu uptake (mainly astrocytes) Glutamate and CNS disorders 1) Stroke Ischemia à no ATP à increase Glutamate à Over activation NMDA R & AMPA R à increase Ca+ à cell death 2) dysfunction of glutamatergic transmission may also involve in schizophrenia-like symptoms, cognitive dysfunction, Depression and memory impairment GABA • Main inhibitory neurotransmitter in the mammalian CNS GABA • Main inhibitory neurotransmitter in the mammalian CNS Ionotropic GABAA Heterooligomeric protein complex that consists of several binding sites coupled to an integral Clchannel Metabotropic GABAB G - protein coupled receptor, seven transmembrane domain protein GABA-A- ionotropic receptor • An integral chloride channel activated by competitive agonists: GABA and muscimol • Blocked by convulsant bicuculine (competitive antagonist) and picrotoxin (noncompetitive antagonist) • Allosterically modulated by benzodiazepines and barbiturates, which potentiate the effect of GABA GABAA receptor Actions at GABAA Receptors GABA A and ethanol l Ethanol facilitates GABA ability to activate the receptor and prolongs the time that the Clchannel remains open GABA Synthesis Glutamate GAD GABA GABA is formed by the α-decarboxylation of glutamate in the reaction catalyzed by GAD (glutamic acid decarboxylase) GABA Degradation GABA GABA-T succinic semialdehyde GABA is catabolized into the succinic semialdehade in the reaction catalyzed by GABA-T (GABA-Transaminase)