Cholinergic Transmission Flashcards
what was the first neurotransmitter discovered?
acetylcholine
in which pathways is ACh implemented?
cholinergic pathways
within the peripheral nervous system, which three systems contain cholinergic pathways?
neuromuscular junctions/ somatic motor system (including motor nerve and skeletal muscle)
and in the autonomous nervous system: the parasympathetic system and the sympathetic system
what is the difference between the sympathetic and the parasympathetic nervous systems?
parasympathetic:
stimulating actions for ‘rest and digest’ or ‘feed and breed’
sympathetic:
responsible for stimulating fight-or-flight actions.
what are the three major locations of cholinergic pathways in the central nervous system?
- interneuron within the striatum
- basal forebrain cholinergic system.
- dorsolateral pons.
what is the ChAT enzyme?
controls the synthesis rate of acetylcholine and coA via controlling precursor availability and neuronal firing
what is the AChE enzyme?
controls the breakdown of Ach
located inside presynaptic terminal to breakdown excess acetylcholine and located on the postsynaptic membrane to provide transmission remportal and spatial precision
what are six AChE blockers?
physostigmine neostigmine pyridostigmine sarin and soman novichok black widow spider venok
describe the AChE blocker physostigmine..
comes from clabar bean seeds and can cross over the BBB
this blocker causes poisoning and induces symptoms such as mental confusion and slurred speech
describe the AChE blockers neostigmine and pyridostigmine…
also known as prostigmin and mestinon
these blockers are synthetic and do not cross the BBB
these blockers can be used to treat myasthenia gravis (a weakness of the muscles disease)
describe the AChE blockers sarin and soman…
these blockers are nerve gases which can cross the BBB.
they produce irreversible outcomes and induce many symptoms including over stimulation of the Ach systems and vomiting.
there is however, an antidote called pyridostigmine
describe the AChE blocker Novichok…
novichok is a secret chemical weapon that is extremely potent and irreversible. novichok can also cross the BBB
what disease can AChE inhibitors be used to treat?
alzheimers as they can prevent the breakdown of Ach which is a common contributer to the disease
what is the enzyme VAChT?
vesicular acetycholine transporter
located at the presynaptic terminal
packages ach into vesicles for secretion
what is VAChT blocker?
versamicol
what are choline transporters?
choline transporters sustain ach synthesis via recylcing choline. they are located in the presynaptic terminal
what are two major cholinergic receptor pathways?
nicotinic and muscarinic
what is the distribution of nicotinic receptors?
located in the neuro-muscular junctions, the autonomous systems and the central nervous system.
what are the physiological effects of the cholinergic pathways in the NMJs, autonomous systems, and the CNS?
NMJs: muscle contraction, breathing, movements.
autonomous systems: activation of nachrs in autonomic ganglia, stimualte adrenaline release, increase metabolic rate.
CNS: influence mood, cognition, and reinforcing effects.
what are four agonists of nAChRs?
nicotine
varenicline tartrate
galantamine hydrobromide
succinylcholine
what are the three categories of nAChR antagonists and their sub-antagonists?
ganglion blockers: mecamylamine (inversine)
neuromuscular blockers: D-tubocurarine, vecuronium, pancuronium, atracurium, and snake toxins.
centrally acting nicotinic antagonists: dextromethophan
describe the distribution of muscarinic receptor subtypes in the peripheral nervous system…
M2Rs: cardiac muscle
M3Rs: smooth muscle cells, beta-cells of pancreas, mediation of other secretory processes
describe the distribution of muscarinic receptors in the central nervous system…
receptors widely distributed throughout the brain, especially M5 receptors.
what are muscarinic receptor agonists?
parasympathetic agents: muscarine, pilocarpine, arecoline
what are muscarinic receptor antagonist?
atropine and scopolamine
