Neurotransmitters Flashcards
Excitatory NTs
Increase Na+ permeability = depolarization
ex: glutamate & Aspartate
Inhibitory NTs
increase Cl- or K+ permeability = hyperpolarization
ex: Glycine (spinal cord & brainstem) & GABA (forebrain)– degraded by transamination
Ach synthesis
Acetyl-CoA + choline –> [choline acetyl transferase]–> Ach
ACh receptors (2)
1) Nicotinic (ligand gated Na+ channels in neuromuscular junction– brain)
2) muscarinic (GPCRs –> IP3 or decrease cAMP)
Acetylcholinesterase & inhibitor
organophosphates are irreversible inhibitors of acetylcholineesterase
- it removes free hydroxyl of serine
used:
1) pesticides
2) “nerve gases”
Tyrosine makes –>
catecholamines (EPI, NE, Dopamine)
Tryptophan makes –>
indoleamines (serotonin)
histidine makes –>
histamine
catecholamine synthesis
L-TYR –> [tyrosine hydroxylase] –> L-DOPA –> [Dopa decarboxylase//B6] –> DOPAMINE –> NE –> EPI
inactivation of catecholamines (NE)
1) taken back up into nerve terminal by Na+ co-transport
2) enzymatic inactivation
MAO = oxidative deamination
COMT = methylation
Synthesis of Indoleamines (& Inactivation)
L-TRYP –> [trp hydroxlase//BioH4] –> 5-HYDROXY TRP –> SEROTONIN –> [acetyl-coa//SAM//a few steps] –> MELATONIN
MAO (oxidative deamination) = inactivation of 5-HT (serotonin)
Degradation product of Dopamine
Homovanillic acid
Degradation product of NE & EPI
Vanillylmandelic acid
Degradation product of 5-HT
5-hydroxyindoleacetic acid
Endorphins
peptides that activate opiate receptors
ex:
1) enkephalins:
NH3-Tyr-Gly-Gly-Phe-Met-COO-
NH3-Tyr-Gly-Gly-Phe-Leu-COO-
2) B-endorphins
