CNS Neurotransmitter Systems

Vocabulary practice focusing on the classification, mechanisms, and clinical significance of CNS neurotransmitters, specifically Glutamate and GABA.

Neurotransmitters

Brain chemicals stored in axon terminals or synapses that transmit signals between neurons and must be synthesized and stored in the presynaptic neuron.

Agonist

Agents, such as neurotransmitters or drugs, which bind to and activate the receptors.

Inverse agonist

Agents that bind to the same receptor as an agonist but induce a pharmacological response opposite to that of the agonist.

Antagonist

Agents which block receptors and prevent agonists or inverse agonists from binding to their respective receptors.

Metabotropic Receptors

A family of G-protein coupled receptors that initiate an intracellular biochemical cascade and mediate slow synaptic neurotransmission.

Glutamate

The main excitatory CNS neurotransmitter that is fast-acting and acts on AMPA, NMDA, Kainate, and mGluR receptors.

Glutaminase

An enzyme used in the synthesis of glutamate from the molecule glutamine.

Vesicular glutamate transporter

A transporter responsible for packing produced glutamate into synaptic vesicles to be ready for release.

Excitatory amino acid transporters

Transporters expressed on presynaptic terminals or astrocytes that take up glutamate to be broken down or recycled into glutamine.

Long term potentiation (LTP)

The strengthening of synapses mediated by glutamate, which is essential for different forms of learning and memory.

Excitotoxicity

A condition occurring in stroke where hypoxia leads to excessive glutamate activity, causing damage to neurons.

Gamma-aminobutyric acid (GABA)

The main inhibitory CNS neurotransmitter that decreases neuronal activity and reduces the likelihood of firing an action potential.

GABA D carboxylic enzyme (GAD)

The enzyme required to synthesize GABA from glutamate.

Vesicular GABA transporter

A transporter that packs GABA into vesicles for release from the presynaptic terminal.

Benzodiazepines

Agonists, such as diazepam, that relieve anxiety and treat status epilepticus by facilitating $GABA_A$ transmission.

Baclofen

A $GABA_B$ agonist used to treat spasticity by inhibiting the release of excitatory transmitters.

Huntington’s disease

A disorder caused by the loss of GABA-containing long projection neurons, resulting in cognitive deficit and uncontrolled movement.