Neurotransmitters

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Glutamate

Exhibitory. Ionotropic receptors (AMPA, NMDA, etc)
NMDA important for learning and memory
Excess = Seizure

GABA

Inhibitory. GABA_A (Ionotropic) and GABA_B (metabotropic).
Balances glutamate.
Excess = coma, unconsciousness, etc.

Acetylcholine

Muscarinic receptors (metabotropic) and Nicotinic receptors (ionotropic)
First NT discovered in Otto Loewi’s frog heart experiment
Cholinergic transmission in the cortex
Linked to Alzheimers

Dopamine

All receptors (D₁-D₅) are metabotropic
Involved in complex behaviors, including motor function, reward, and higher cognition. Found throughout the forebrain.
*Reward system!

Norepinephrine

All receptors (α1, α2, β1, β2, and β3) are metabotropic.
Alert and arousal. Sympathetic nervous system. Flight or fight responses.

Serotonin

All receptors except 5-HT₃ are metabotropic.
Controls behavior, mood, vision, anxiety, s** behavior, and sleep
Many drugs target serotonin there are subtypes for specification.

Amino acids

Most abundant transmitters. Vital for healthy functionals.
Glutamate, GABA, and glycine

Amine

Four major neurotransmitter systems; acetylcholine, dopamine, norepinephrine, serotonin. Involved in similar systems, but have their own structures (distinct and overlapping).

Peptides

opioid peptides like endorphins are mimicked by opiates such as morphine to reduce the perception of pain.
Oxytocin and vasopressin peptide hormones contribute to memory and pair-bonding. Synthesized by the hypothalamus

Gas

Produced on demand by outside axon terminals and diffuses out of neuron (so not held in vesicles). No receptors; diffuses to target cell and activates second messengers. Can function as a retrograde transmitter.

Mesostriatal pathway:

Involved in dopamine
Substantia nigra to basal ganglia

Mesolimbocortical pathway

Involved in dopamine
Midbrain (ventral tegmental area) to limbic system (nucleus accumbens) to cortex.