Posted by zeugma on February 25, 2006, at 19:01:52
In reply to Re: What exactly is acetylcholine (ACh) ??, posted by linkadge on February 25, 2006, at 14:03:27
Acetylcholine, in susceptible individuals, induces depression, and I do not believe this is linked to excessive intellection/reflection. It's really one of the many ideas that have been floated around to explain why some are more depressed than others; it was popular when the TCA's were the most common antidepressants, but dropped when other drugs and neurotransmitters became more fashionable. But never disproved, of course. Nothing in the realm of affective disorders ever appears to be proved or disproved- just dropped when more 'interesting' ideas come along.
But a rat strain, developed when acetylcholine was a neurotransmitter of great interest to theorists, is still here, and note its characteristics:
Neurosci Biobehav Rev. 2005;29(4-5):739-59. Epub 2005 Apr 22.
The Flinders Sensitive Line rat: a selectively bred putative animal model of depression.Overstreet DH, Friedman E, Mathe AA, Yadid G.
Department of Psychiatry, Skipper Bowler Center for Alcohol Studies, University of North Carolina at Chapel Hill, CB #7178, Thurston-Bowles Bldg 3009, Chapel Hill, NC 27599-7178, USA. dhover@med.unc.edu
The Flinders Sensitive Line (FSL) rats were originally selectively bred for increased responses to an anticholinesterase agent[which increases acetylcholine levels in the nervous system- certain pesticides are such agents, I believe]. The FSL rat partially resembles depressed individuals because it exhibits reduced appetite and psychomotor function but exhibits normal hedonic responses and cognitive function. The FSL rat also exhibits sleep and immune abnormalities that are observed in depressed individuals. Neurochemical and/or pharmacological evidence suggests that the FSL rat exhibits changes consistent with the cholinergic, serotonergic, dopaminergic, NPY, and circadian rhythm models but not the noradrenergic, HPA axis or GABAergic models of depression. However, evidence for the genetic basis of these changes is lacking and it remains to be determined which, if any, of the neurochemical changes are primary to the behavioral alterations. The FSL rat model has been very useful as a screen for antidepressants because known antidepressants reduced swim test immobility when given chronically and psychomotor stimulants did not. Furthermore, rolipram and a melatonin agonist were shown to have anti-immobility effects in the FSL rats and later to have antidepressant effects in humans. Thus, the FSL rat model of depression exhibits some behavioral, neurochemical, and pharmacological features that have been reported in depressed individuals and has been very effective in detecting antidepressants.
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It is fortunate that the rats outlive the often flighty theorists that literally spawned them.
-z
poster:zeugma
thread:612749
URL: http://www.dr-bob.org/babble/alter/20060130/msgs/613286.html