Rivlin Lab

A simple guide to understanding how neurons make neurotransmitters Your brain has different classes of neurons, each defined by the chemical messenger (neurotransmitter) they release. These transmitters are built from specific precursors using unique enzymes and cofactors. 1️⃣ Cholinergic Neurons (green) Main transmitter: Acetylcholine (ACh). Source: Built from acetyl-CoA and choline. Special enzyme: ChAT (choline acetyltransferase). 🟢 Example: These neurons drive muscle contraction and attention. 2️⃣ GABAergic Neurons (blue) Main transmitter: GABA (gamma-aminobutyric acid). Source: Derived from glutamate. Special enzyme: GAD (glutamate decarboxylase). 🟢 Example: GABA is the brain’s main “calm-down” signal. 3️⃣ Glutamatergic Neurons (orange) Main transmitter: Glutamate. Source: Recycled from other cells and stored in vesicles. 🟢 Example: Glutamate is the brain’s main “go” signal for learning and memory. 4️⃣ Serotonergic Neurons (green-teal) Main transmitter: Serotonin (5-HT). Source: Made from tryptophan → 5-HTP → serotonin. Special enzymes: TPH (tryptophan hydroxylase), DDC (decarboxylase). Cofactor: BH₄ (tetrahydrobiopterin) 🟢 Example: Serotonin regulates mood, sleep, and appetite. 5️⃣ Dopaminergic Neurons (light blue) Main transmitter: Dopamine. Source: Made from tyrosine → L-DOPA → dopamine. Special enzyme: TH (tyrosine hydroxylase), DDC. Cofactor: BH₄. 🟢 Example: Dopamine drives motivation, reward, and movement. 6️⃣ Noradrenergic / Octopaminergic Neurons (red) Main transmitter: Norepinephrine (mammals) or Octopamine (in invertebrates). Source: Derived from tyrosine/tyramine. Special enzyme: TBH (tyramine β-hydroxylase). Cofactor: BH₄. 🟢 Example: Linked to arousal and “fight or flight.” 7️⃣ Tyraminergic Neurons (orange-brown) Main transmitter: Tyramine. Source: Made from tyrosine → tyramine. Special enzyme: TDC (tyrosine decarboxylase). 🟢 Example: Acts as a trace amine, modulating dopamine and serotonin systems. Supporting Pathways (Panels B & C): Acetyl-CoA production (B): from the citric acid cycle, provides building blocks for acetylcholine. BH₄ synthesis (C): a critical cofactor for making serotonin, dopamine, and norepinephrine. Each neurotransmitter system has its own “assembly line”: specific precursors, enzymes, and cofactors. Together, they form the brain’s chemical language — acetylcholine for movement and attention, glutamate and GABA for balance, and monoamines (serotonin, dopamine, norepinephrine) for mood, reward, and arousal.