Cholinergic
Cholinergic agents are compounds which mimic the action of
The parasympathetic nervous system, which uses acetylcholine almost exclusively to send its messages, is said to be almost entirely cholinergic. Neuromuscular junctions, preganglionic neurons of the sympathetic nervous system, the basal forebrain, and brain stem complexes are also cholinergic, as are the receptor for the merocrine sweat glands.
In neuroscience and related fields, the term cholinergic is used in these related contexts:
- A substance (or ligand) is cholinergic if it is capable of producing, altering, or releasing acetylcholine, or butyrylcholine ("indirect-acting"), or mimicking their behaviours at one or more of the body's acetylcholine receptor ("direct-acting") or butyrylcholine receptor types ("direct-acting"). Such mimics are called parasympathomimetic drugs or cholinomimetic drugs.
- A receptor is cholinergic if it uses acetylcholine as its neurotransmitter.[2]
- A synapse is cholinergic if it uses acetylcholine as its neurotransmitter.
Cholinergic drug
Structure activity relationship for cholinergic drugs
- A molecule must possess a nitrogen atom capable of bearing a positive charge, preferably a quaternary ammonium salt.
- For maximum potency, the size of the alkyl groups substituted on the nitrogen should not exceed the size of a methyl group.
- The molecule should have an oxygen atom, preferably an ester-like oxygen capable of participating in a hydrogen bond.
- A two-carbon unit should occur between the oxygen atom and the nitrogen atom.
- There must be two methyl groups on the nitrogen
- A larger third alkyl group is tolerated but more than one large alkyl groups leads to loss of activity
- The overall size of the molecule cannot be altered much. Bigger molecules have poorer activity
Cholinergic hypothesis of Alzheimer's disease
The hypothesis states that a possible cause of AD is the reduced synthesis of acetylcholine, a neurotransmitter involved in both memory and learning, two important components of AD. Many current drug therapies for AD are centered on the cholinergic hypothesis, although not all have been effective. Studies performed in the 1980s demonstrated significant impairment of cholinergic markers in Alzheimer's patients.[4]
Thus it was proposed that degeneration of cholinergic neurons in the basal forebrain and the associated loss of cholinergic neurotransmission in the cerebral cortex and other areas contributed significantly to the deterioration in cognitive function seen in patients with Alzheimer's disease[5]
Further studies on the cholinergic system and AD demonstrated acetylcholine plays a role in learning and memory.
When young adults perform memory and attention tasks, brain activation patterns are balanced between the
AD is currently treated by increasing acetylcholine concentration by using
See also
- Adrenergic
- Anticholinergic
- Dopaminergic
- GABAergic
- Glutamatergic
- moly (herb)
- Nootropic
- Racetam
- Serotonergic
- Nicotinic acetylcholine receptor
References
- ISBN 978-0-444-52166-8.
Cholinomimetics or cholinergic drugs are those drugs that cause effects similar to those resulting from introduction of acetylcholine, or simulation of ganglions of the parasympathetic nervous system. These drugs imitate action of endogenously released acetylcholine.
- ^ "Dorlands Medical Dictionary:cholinergic receptors".[permanent dead link]
- ^ "Medicinal Chemistry of Adrenergics and Cholinergics". Archived from the original on 2010-11-04. Retrieved 2010-10-23.
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- ^ PMID 16788077.
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