The expression level of muscarinic M1 receptor subtypes in different regions of rat brain

Abstract

Objectives: Post-traumatic stress disorder (PTSD) is characterized by life threatening trauma, overexcitation, flashbacks and nightmares. Research on PTSD is faced with the challenge of understanding how a traumatic experience leads to long lasting detrimental effects on behavior and functions of the brain. Many pharmacological agents are available in the pharmacotherapy of the PTSD where there is no adequate evidence to support the efficacy of any specific agent. It is hypothesized that M1 muscarinic receptor subtypes might play important role in the recall of negative experience. The aim of this research is to investigate both the behavioral and the molecular efficacy of chronic fluoxetine (FLU) (2.5mg/day; i.p) treatment in PTSD and also the probable effect of pharmacotherapy on M1 muscarinic receptor subtype expression in rats. Materials and Methods: For experimental design random selection was performed to all groups; Control, Stress and Treatment groups. The effects of chronic FLU treatment were evaluated in terms of expression levels of the M1 receptors in the hippocampus and the frontal cortex of the rats’ brain. Results: When the rats were subjected to the trauma reminder on the last day of the experiment (Day 30), the anxiety indexes of the stress group were found to be significantly higher than the control (P< 0.001). Moreover, it has been observed that chronic FLU treatment restored the anxiety scores in stress groups by lowering the anxiety indexes (P< 0.001). Conclusion: In this study, it has been indicated that stress induces anxiety like behavior and reduces M1 expression in the hippocampus and the frontal cortex of the rats’ brain. These effects can be prevented by lowering the dose of chronic FLU therapy.