Behavioral Depression in the Swim Test Causes a Biphasic, Long-lasting Change in Accumbens Acetylcholine Release, with Partial Compensation by Acetylcholinesterase and Muscarinic-1 Receptors.
From: Laboratory of Behavioral Physiology, Medical School, University of Los Andes, Merida, Venezuela. radap@ula.ve
Neuroscience
- Publish Date: Aug 2006
- ISSN: 0306-4522
- Volume: 141
- Issue: 1
- Pages: 67-76
- Medium: Print
- Language: English
- Citation (JAMA): Rada P, Colasante C, Skirzewski M, et al. Behavioral Depression in the Swim Test Causes a Biphasic, Long-lasting Change in Accumbens Acetylcholine Release, with Partial Compensation by Acetylcholinesterase and Muscarinic-1 Receptors.. Neuroscience Aug 2006;141:67-76
Abstract
The nucleus accumbens may play a role in acquisition and expression of behavioral depression as measured using the inescapable swim test. Previous work shows that a local injection of a cholinergic muscarinic-1 receptor agonist increases immobility and a specific muscarinic-1 antagonist acts as an antidepressant-like drug by increasing swimming escape efforts. The present study used microdialysis to monitor extracellular acetylcholine levels in the accumbens, fluorescent labeled toxins to monitor changes in acetylcholinesterase and muscarinic-1 receptors, and semiquantitative-polymerase chain reaction to detect changes in gene expression for the muscarinic-1 receptor. Microdialysis showed that acetylcholine levels did not change while an animal was swimming; however, a significant transient decrease occurred when the rat was returned to the dialysis cage, followed by a long-lasting increase that reached a maximum three hours after the test. Acetylcholine levels stayed high even 24 h after the initial test as evidenced by a significant elevation in basal level prior to the second swim. This increase in neurotransmitter may have been partially compensated by a significant increase in the degradative enzyme, acetylcholinesterase, and by a decrease in muscarinic-1 receptors and their gene expression. These results further demonstrate the importance of accumbens cholinergic function in the appearance of a depression-like state.
Mesh Headings (Keywords): Acetylcholine, Acetylcholinesterase, Analysis of Variance, Animals, Behavior, Animal, Blotting, Northern, Cell Count, Chromatography, High Pressure Liquid, Depression, Disease Models, Animal, Fluorescent Antibody Technique, Male, Microdialysis, Nucleus Accumbens, RNA, Messenger, Rats, Rats, Sprague-Dawley, Receptor, Muscarinic M1, Reverse Transcriptase Polymerase Chain Reaction, Swimming, Time Factors
Check for Full Text / PubMed Unique Identifier (PMID): 16677771
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