neuro Flashcards
(22 cards)
AchE- Acetyl choLine esterase
Target of nerve gases sarin, insecticides, drugs ( physostigmine- glaucoma) In the synapse released made in the postsynaptic neuron
Tyrosine Hydroxylase
RLS - Rate limited enzyme Catchecholamines Synthesis Tyrosine–> LDOPA
AADC Aromatic Amino acid Decarboxylase
AADC= L-DOPA 5- Hydroxytryptophan–> 5’ HydroxyTryptamine
COMT
Catechola-O-methyltrasnferase Liver, PNS
MAO
Mitochondrial Monoamine oxidase
PNMT
Phenylethanolamine-N_methyltrasnferase NE–> E in the cytoplasm Site: Only in epinephrine neurons and Adrenals
SERT
Serotonin re-uptake inhibitors Target of SSRIs
Ionotropic Vs Metabotropic
Ionotropic- ligand gated- causes a conformational change leading to ion channel opening
Fast msec
direct gating
ion selectivity- size and charge
Kinetics of binding, how wide channel opens, ions conc
Metabotropic- GPCR- no channel- confirmational change
indirect gating of an ion channel ( not directly through there channel However)
2nd messenger cascades
slower -longer lasting
even change in transcription
ChAT.
Choline + acetyl CoA ——> choline acetyltransferase (ChAT) —> acetylcholine (ACh). Choline is produced endogenously in the liver and by membranes RLS_ the amount of choline that is available in the presynaptic neuron is the rate limiting factor for the production of ACh.
Norepinephrine
Only NT made in the vesicles identifies NE neurons Dopamine Beta- hydroxylase DA-Beta- (DBH) Dopamine–> NE
L-Tyrosine
Hydroxyphenylalanine Catecholamine Synthesis precursor L-tyrosine— ( tyrosine- hydroxylase- RLS) > L Dopa
Catecholamines Synthetic Pathway
Tyrosine Hydroxylase is the Rate Limiting Step

Serotonin (5-HT) Synthesis, Release & Inactivation

- Active transport of tryptophan into cell
- Tryptophan converted to 5-hydroxytryptophan by tryptophan-5-hydroxylase (rate limiting step)
- 5-hydroxytryptophan is converted to serotonin (5-HT; 5-hydroxytryptamine) by aromatic L-amino acid decarboxylase (AADC)
- Serotonin is actively transported into the storage vesicles
- Ca2+ mediated exocytosis/release of 5-HT; NT diffuses across the cleft and binds to its postsynaptic receptor
- Re-uptake/removal of serotonin by specific presynaptic transporter (SERT)
- Serotonin is metabolized by mitochondrial MAO or reloaded into vesicles.
Metabotropic Receptors
Indirect gating
Can direct the flow of ions
Ions DONOT flow through***
Dont directly form ion pores
cause opening of a neighboring ion channels
Ie Muscarinic AchR
Ionotropic Receptors
Ligand- Gated ion channel
Direct gating
Same receptor - binds ligand- then the channel opens for the ion
ie- Nicotinic Receptor AcHR on the SKELETAL muscles to get a quick response
Sympathetic & Parasympathetic NTs and Receptors

Note in this diagram that CNS neurons innervate muscle directly while other CNS neurons synapse onto specific ganglia or chromaffin cells in the adrenal glands. Take special note of the NTs released at each synapse and the respective receptors present on the post-synaptic cells.
Important for this block, chromaffin cells are neuroendocrine cells found mostly in the medulla of the adrenal glands. Notice that sympathetic neurons (presynaptic cell) release ACh onto chromaffin cells (postsynaptic cell) which express nicotinic receptors. Activation of nicotinic receptors causes the release of E/adrenaline and NE/noradrenaline from the chromaffin cells into the circulation, where these NTs affect multiple organs.
NOTE: postsynaptic cells innervated by sympathetic neurons/chromaffin cells express nicotinic receptors (ionotropic) while postsynaptic cells innervated by parasympathetic neurons can have muscarinic receptors (GPCRs)
Serotonin (5-HT) influences peripheral tissues

Serotonin (5-HT) is a NT that has CNS and peripheral targets.
It is important in the regulation bone remodeling (SSRI’s decrease bone density), lipolysis, glucose metabolism, bone marrow and gut microbiome.
TPH1 - receptor for 5 HT ??
Sympathetics

Sympatheitcs T1-L2
-
One of 3 routes:
- Sympathetic chain ganglia
- Collateral ganglia
- Adrenal Gland
- All have Nicotinic Receptors–> quick Response–> Ionotropic***
Input
Afferent
PNS
Dorsal Alar Pate
Output
Efferent
PNS
Motor Neurons In the Basal Plate
output to
- Autonomic ganglia
- Motor nerves