ch12 neurotransmitters

Acetylcholine

Released by many PNS & some CNS neurons – Excitatory on NMJ but inhibitory at other synapses

Amino Acids

Glutamate, GABA, Glycine

Glutamate

released by nearly all excitatory neurons in
the brain ---- inactivated by reuptake (by neurons) and
uptake (by neuroglia)

GABA

inhibitory neurotransmitter for 1/3 of all brain
synapses (antianxiety drugs (e.g. Valium) = enhance
inhibitory effect of GABA

Glycine

inhibitory neurotransmitter in the spinal
cord

Norepinephrine

Fight-or-flight response in PNS – Awakening, dreaming, mood regulation in CNS

Dopamine

Addiction/rewards, pleasure, emotions and muscle function
(Parkinson = reduced dopamine)

Serotonin

Mood regulation, appetite, temperature control, sleep – Prozac = serotonin reuptake inhibitor

Nitric oxide

Excitatory NT with widespread effects in the body • Extremely short half-life (because so reactive!) – May play a role in memory and learning – Plays a major role in vasodilation (lower BP, erection)

Carbon monoxide

Excitatory NT in brain – May play a role in memory and circadian rhythms – Also plays a role in vasodilation (increase blood flow locally)

Enkephalins (neuropeptides)

These are ‘opioid peptides’ that function as natural
painkillers and have been linked to many other biological
processes (i.e. memory, learning, puberty, sexuality,
depression)

Substance P

enhances our perception of pain – Enkephalin and endorphin have pain-relieving effect by blocking the release of substance P

Diffusion

Neurotransmitters move away from synaptic cleft (down
concentration gradient)

Enzymatic degradation

Enzymes degrade neurotransmitter (e.g. Ach esterase)

Uptake by glial cells or reuptake by neurons

Neurotransmitters get into neurons or glial cells by endocytosis
(e.g. Prozac = serotonin reuptake inhibitor)