neurotransmitters and main functions

acetylcholine synthesis =

acetyl CoA + choline --> acetylcholine - uses choline acetyl transferase ChAT

acetylcholine breakdown

acetylcholine --> acetate + choline - uses acetylcholinesterase

2 types of receptors on postsynaptic neurons

muscarinic, nicotinic

nicotinic receptors are present in ..

neuromuscular junctions, brain, autonomic nerves

muscarinic receptors are present in ..

smooth muscle, exocrine glands, brain

nicotinic agonist

nicotine

nicotinic antagonist

curare

muscarinic agonist

muscarine (toadstool)

muscarinic antagonist

Atropine

neuropathological changes in alzheimer's disease

loss of brain weight - shrinking, enlargement of brain ventricles, numerous senile plaques and neurofibrillary tangles

how does acetylcholine link to AD

acetylcholine is important for memory and attention - cholinergic neurons die early in AD

AD treatment uses ..

acetylcholinesterase inhibitors (donepezil, rivastigmine, galatamine)

egs of catecholamines

dopamine, adrenaline, noradrenaline

catechol group is..

phenol ring with OH group in 3&4 positions

catecholamines are synthesised from ..

tyrosine

catecholamine catabolism involves ..

monoamine oxidase and catechol-0-methyltransferase

D1 like receptors

D1 and D5, coupled to G stimulatory proteins - stimulate adenylate cyclase

D2 like receptors

D2, 3, 4 - coupled to inhibitory G proteins - inhibits adenylate cyclase

cause of parkinson's disease

degeneration of dopaminergic neurons in the substantia nigra pars compacta and loss of dopamine in the caudate-putamen

how are parkinsons motor symptoms alleviated

treatment with L-dopa which is converted to dopamine in brain

what is used to prevent premature conversion of L-dopa to dopamine

a peripherally active dopa decarboxylase

what can be used to inhibit dopamine degradation

inhibitors of COMPT and MAO-B

serotonin synthesis

from tryptophan, by tryptophan hydroxylase and 5-HTP decarboxylase

serotonin catabolism

broken down to 5-hydroxyindoleactic acid by MAO and aldehyde dehydrogenase

5-HT can bind to … different receptors which are all ..

14. G protein coupled, except for 5HT3 (ligand gated ion channel)

how is serotonin action stopped

mainly by reuptake from synapse via 5HT transporter on presynaptic neuron

excitatory amino acid transmitters

glutamate and aspartate

inhibitory amino acid transmitters

glycine and GABA

GABAa receptor

ionotropic receptor coupled to Cl- channel - has modulatory binding sites

GABAb receptor

metabotropic receptor coupled to Ca2+ and K+ channels via G proteins and second messenger systems

NMDA receptors bind ..

glutamate, glycine, Mg2+, Zn2+ and polyamines- form cation-permeable channels

kainate and AMPA only interact with ..

glutamate and their specific agonists

MGluRs are..

G protein coupled receptors which trigger a second messenger cascade

astrocyte function

buffer glutamate and GABA concentrations

how do astrocytes work

remove GABA/glutamate from synapse via transporters and catabolise them

memantine function

blocks Mg2+ binding site on glutamate NMDA receptor

peptide neurotransmitters features

many types - slow postsynaptic effects, actions terminated by extracellular proteases

other types of neurotransmitter

purines, histamine, gases eg. nitric oxide