10/ synapses and nts 3 Flashcards
what is ChAT? what is it used as?
- choline acetyl transferase
- enzyme that converts choline and acetyl CoA into ACh
- good marker for cholinergic neurons
when is acetyl CoA produced
cellular respiration in mitochondria
whats ACh broken down by AChE into
choline
acetic acid
what types of receptor does ACh act on? brain proportions of each type
- nicotinic (ionotropic). nAChRs. ACh gated sodium/calcium channel. found at neuromuscular junction and CNS
- muscarinic (metabotropic). mAChRs. 5 types - M1,3,5 excitory vis Gq, M2,4 inhib via Gi/o. CNS and ANS
- brain has 10-100 X more m than n
what chemicals block ACh release
- botulinum toxin
- black widow spider venom
what chemicals block AChE
- nerve gas
- organophosphate pesticides
- alzheimers treatments
what chemicals activate ACh receptors
- nicotine, muscarine
- neonicotinoid pesticides - over activates and kills insect
what blocks ACh receptors
- nicotinic: curare, alpha bungarotoxin
- muscarinic: atropine (antidote for nerve gas. also causes pupil dilation and increased hr bc ach used by ANS)
what are monoamines synthasised from
- amino acids
- include catecholamines and serotonin/5HT -NTs
serotonin/5HT
- aa tryptophan (LIMITING FACTOR)
- make 5 HTP
- make 5HT
storage of monoamines
- packed into vesicles by vesicular monoamine transporters - VMAT
removal of monoamines
- removed from synaptic cleft by specific re uptake transporters
- destroyed by monoamine oxidase MAO and catechol-O-methyltransferase COMT (on post SN, only catecholamines)
catecholamines formation
- subcategory of catechol w aa
- start w tyrosine aa
- make dopamine precursor L dopa using TH enzyme (TH is LIMITING FACTOR)
- make dopamine
- make noradrenaline
- make adrenaline
what type of receptor are monoamine receptors most often
- GPCRs
dopamine receptors
- D1 like: D1, D5
- D2 like: D2, D3, D4
nor/epinephrine receptors
adrenergic receptors, alpha and beta types (beta blockers)
serotonin/5HT receptors
7 receptors, one is a ligand gated sodium/potassium channel
broad areas dopamine is involved in
reward, movement
dopamine - motor control
- dopaminergic neurons in substantia nigra project to the striatum
- this nigrostriatal pathway facilitates initiation of voluntary movement
what is parkinsons disease caused by
- death of dopaminergic neurons
how can parkinsons be treated
- increasing dopamine by…
- giving L dopa (TH enzyme making it is limiting)
- dopamine cant cross bbb
- MAO-B inhibitors. blocks monoamine oxidase which destroys dopamine
dopamine reward
- dopaminergic neurons in ventral tegmental area VTA project to cortex and limbic system
- this mesolimbic pathway mediates reward and motivation
what happens through intra cranial self stimulation of the mesolimbic pathway
extremely rewarding - target for addiction
what and how do noradrenergic neurons regulate
- arousal mainly, also sleep wake, attention, mood, anxiety, pain…
- small number in the locus coeruleus innervate the whole brain
