Posted by rina on September 22, 2007, at 1:47:17
In reply to Muscarinic receptors and bipolar, posted by Jimmyboy on September 21, 2007, at 15:12:05
In the bulbectomised rat model of depression, a decrease in cortical muscarinic receptors occurs that returns to control values following treatment with antidepressants (Earley et al, 1994).
The anticholinergic activity of the tricyclic antidepressants is usually associated with their unacceptable peripheral side-effects and most second-generation antidepressants lack such side-effects.
Possible support for a cholinergic hypothesis of depression is that the cholinesterase inhibitor pyridostigmine, when administered to drug-free patients with depression, causes an enhanced activation of the anterior pituitary glands, as shown by the release of growth hormone (O'Keane et al, 1992).
This suggests that the muscarinic receptors are supersensitive in patients with depression. Janowsky et al (1986) postulated that depression arises as the result of an imbalance between the central noradrenergic and cholinergic systems; in depression, the activity of the former system is decreased and, conversely, in mania it is increased.
As most antidepressants enhance noradrenergic function, it is hypothesised that the reduction in cholinergic activity is a consequence of the increase in noradrenergic activity.
poster:rina
thread:784340
URL: http://www.dr-bob.org/babble/20070919/msgs/784443.html