NRSC 1110 Ch 6

Acetylcholine

ACh, produced by choline and acetyl coA

Cholinergic

Referring to cells that use acetylcholine as their synaptic transmitter.

choline acetyltransferase (ChAT)

enzyme that synthesizes ACh

Membrane transporters

co transporters, move with direction of flow of the other ion

Vesicular transporters

counter transporters, move against the direction of flow for the other ion

vesicular ACh transporter (VAChT)

moves ACh into vesicles

acetylcholine esterase (AChE)

enzyme that breaks down ACh into choline and acetic acid; choline is recycled via Na+ cotransporter

Catecholamines

dopamine, norepinephrine, epinephrine; subclass of monoamines

Tyrosine

derivation for catecholamines

tyrosine hydroxylase (TH)

enzymatic catalyst, converts tyrosine to DOPA; rate limiting enzyme

Dopa

A chemical precursor of dopamine and the other catecholamines, formed from tyrosine

DOPA decarboxylase

converts DOPA to dopamine

dopamine beta hydroxylase

converts dopamine to norepinephrine

Phentolamine N methyltransferase PNMT

converts NE to epinephrine

DAT and NET

reuptake of catecholamines

Monoamine oxidase (MAO) and Catecho-O methyltransferase (COMT)

degredation of catecholamines

Indolamine

Serotonin (5-HT)

Tryptophan

makes serotonin

tryptophan hydroxylase

converts tryptophan to 5-HTP; rate limiting step

Aromatic L-amino acid decarboxylase

converts 5-HTP to serotonin 5-HT

VMAT2 (vesicular monoamine transporter 2)

packaging of serotonin

SERT

serotonin transporter; reuptake

MAO

degradation of serotonin in the cytosol

SSRI

selective serotonin reuptake inhibitor

amino acid neurotransmitters

glutamate, GABA, glycine

proteinogenic amino acids

Glutamate and glycine

non-proteinogenic amino acids

GABA

VGLUT 1,2,3

packaging of glutamate

EAATs

reuptake of glutamate from the synaptic cleft; in neurons and astrocytes

GABA

inhibitory neurotransmitter

glutamic acid decarboxylase (GAD)

Enzyme that transforms glutamate into GABA.

vGATs

packaging of GABA

GAT transporter

reuptake of GABA

GABA-T

enzyme that degrades GABA, becomes succinate

Endocannabinoids

lipids, retrograde messengers, synthesized in response to increase Ca2+

Parkinson's

lack of dopamine

Epilepsy

lack of GABA; GABA inhibits brain activity, so lack of GABA means too much brain activity \= seizures

Myathenia gravis

syndrome characterized by muscle weakness; lack of ACh

Nitric oxide

retrograde messenger

Arginine

synthesizes Nitric oxide

Receptor subtypes

receptors with different characteristics in different tissues

nicotinic receptors

cholinergic receptors that also respond to stimulation by nicotine

muscarinic receptors

Cholinergic receptors that are metabotrophic

Three types of ionotropic glutamate receptors

AMPA, Kainate, NMDA

NMDA

glutamate receptor, allows flow of Na and Ca

coincidence detectors

needing multiple "situations" to occur at once to open

GABA a receptor

a chloride channel that causes hyperpolarization of the membrane- inhibitory

Signal amplification

turns one signal molecule into multiple second messenger molecules

Heterotrimeric G proteins

A large group of proteins consisting of three subunits (α, β, and γ) that can be activated by exchanging bound GDP for GTP, resulting in the liberation of two signaling molecules‚ αGTP and the βγ dimer.

Short-cut pathway

effector protein is an ion channel

GPCR structure

3 subunits with GDP bound to alpha

G alpha s

activates adenylyl cyclase; increase protein phosphorylation

G alpha q

Stimulates phospholipase C (PIP2), increase protein phosphorylation, activate calcium binding proteins

G alpha i

inhibits adenylyl cyclase, decreases cAMP

mGluR

metabotropic glutamate receptor (8 of them)

Protein phosphatases

Enzymes that can rapidly remove phosphate groups from proteins.

Divergence

transmitter activating more than one receptor subtype \= greater post synaptic response

Convergence

different transmitters converge to affect same system