Neurotransmitters are chemical messengers used by neurons (nerve cells) to communicate with each other and with other types of cells. They transmit signals across synapses (gaps between neurons) to regulate numerous functions including mood, memory, muscle movement, and organ control.
🧠 Major Types of Neurotransmitters
| Class | Neurotransmitter | Main Functions | Associated Disorders |
| Excitatory Amino Acids | Glutamate | Primary excitatory NT in CNS, learning, memory | Stroke, epilepsy, ALS |
| Inhibitory Amino Acids | GABA (gamma-aminobutyric acid) | Primary inhibitory NT in CNS | Anxiety, epilepsy |
| Monoamines | Dopamine | Reward, motivation, motor control | Parkinson’s, schizophrenia, addiction |
| Serotonin (5-HT) | Mood, appetite, sleep, cognition | Depression, anxiety, migraine | |
| Norepinephrine (noradrenaline) | Alertness, attention, stress response | ADHD, depression | |
| Epinephrine (adrenaline) | Fight-or-flight response | Hypertension, panic disorder | |
| Acetylcholine | Acetylcholine (ACh) | Muscle activation, memory, parasympathetic activity | Alzheimer’s disease, myasthenia gravis |
| Neuropeptides | Endorphins, Substance P | Pain modulation, reward, mood | Chronic pain, depression |
| Purines | Adenosine, ATP | Sleep regulation, energy transfer | Sleep disorders, fatigue |
| Gasotransmitters | Nitric oxide (NO) | Vasodilation, neurotransmission | Neuroinflammation, stroke |
| Trace Amines | Tyramine, tryptamine | Modulate monoamine systems | Under research |
🔁 Synthesis & Recycling
- Most neurotransmitters are synthesized in the neuron terminal from precursor molecules (often small molecules or amino acids).
- Reuptake transporters and enzymes (e.g., MAO, COMT, acetylcholinesterase) break down or recycle neurotransmitters after release.
🧪 Clinical Applications
- Antidepressants (SSRIs, MAOIs) → modulate serotonin, norepinephrine
- Antipsychotics → block dopamine receptors
- Benzodiazepines → enhance GABAergic activity
- Stimulants → increase dopamine/norepinephrine for ADHD
- Alzheimer’s drugs → prevent breakdown of acetylcholine