Neurotransmitters and NMDA Receptor Pathophysiology

Practice flashcards covering NMDA receptor mechanisms, antagonists, Orexin systems, and the Serotonin synthesis pathway, following the lecture notes.

NMDA (N-methyl-D-aspartate) Receptor Overstimulation

Triggered by hypoxia, hypoglycemia, and high nitric oxide levels; leads to increased glutamate, excessive calcium influx, and neuronal damage (apoptosis).

Aspartate

An NMDA receptor agonist used in neurotransmission.

Magnesium ($Mg$)

An NMDA antagonist used for Preeclampsia treatment, as an antiarrhythmic, laxative, tocolytic, anticonvulsant, neuroprotective agent, and vasodilator.

Dizocilpine

An NMDA receptor antagonist categorized as an experimental psychosis drug.

Ketamine

An NMDA receptor antagonist used as a general anesthetic.

Phencyclidine (PCP)

An NMDA receptor antagonist utilized as an experimental psychosis drug.

Biperiden

An NMDA antagonist used in the treatment of extrapyramidal side effects associated with Parkinson's.

Riluzole

An NMDA receptor antagonist used for the treatment of Amyotrophic Lateral Sclerosis (ALS).

Memantine

An NMDA receptor antagonist used for the treatment of Alzheimer's disease.

Felbamate and Valproic acid

Antiepileptic drugs that function as NMDA receptor antagonists.

Acamprosate

An NMDA receptor antagonist used in the treatment of alcohol addiction.

Amantadine

A drug with dopaminergic, anticholinergic, and antiviral properties that also acts as an NMDA antagonist.

Orexins (Hypocretins)

Peptide-structured neurotransmitters responsible for glutamate release, excitation, and wakefulness.

$OX_1$ and $OX_2$

G protein-coupled receptors specifically for orexins.

Tryptophan hydroxylase

The enzyme that converts L-Tryptophan into L-5-Hydroxytryptophan using $O_2$ and Tetrahydrobiopterin as cofactors; inhibited by Chlorphenylalanine.

L-Aromatic amino acid decarboxylase

The enzyme responsible for converting L-5-Hydroxytryptophan to 5-Hydroxytryptamine (Serotonin/$5-HT$) using Vitamin $B_6$ as a cofactor.

5-Hydroxyindoleacetic acid (5-HIAA)

A metabolic product of serotonin produced via MAO-A and aldehyde dehydrogenase ($NAD$); it serves as a marker for carcinoid tumors.

Melatonin Synthesis

A pathway where serotonin ($5-HT$) is converted to N-acetyl-$5-HT$ by $5-HT$ N-acetylase and then to melatonin by Hydroxyindole O-methyltransferase.