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OBJECTIVES: Many clinical reports describe the beneficial effects of low-dose atypical antipsychotic added to the antidepressants in the management of anxiety disorders. The aim of this study was to evaluate the effect of low-dose atypical antipsychotic when added to antidepressant treatment on cholinergic M1 receptor expression in the hippocampus and amygdale region in learning and cognitive disorders caused by anxiety.
METHODS: The treatments were administered by using different test models on memory, learning, and anxiety, as well as the effect on muscarinic M1 receptor expression levels were assessed. Citalopram (10 mg/kg/sc) and combination [citalopram and risperidone (1 mg/kg/ sc)] treatments were applied after stress induction using the immobilization model in rats. Animals groups were randomly divided as: control, stress, stress + citalopram, and stress + combination treatment group. Rats in stress groups were immobilized in cages for 4 h a day for 15 days. On days 1–5, groups were subjected to Morris water maze (MWM), open field, and elevated plus maze (EPM) tests.
RESULTS: MWM test results have shown that citalopram induces an anxiolytic effect. Low-dose risperidone treatment has increased the antidepressant-like activity of citalopram in all tests. In OFT the number of squares that rats were circulating on the plane was increased and the time spent by the rats on the maze platform was also increased in MWM. In addition to this, the time spent by the rats on the open arms of the EPM test were also increased. Since the combined treatment increased the discovery of the environment and the active behaviour in tests; all those reflected the increase in general activity. Findings also suggest that treatments may play an effective role in altering the expression level of M1 receptors which are effective in learning and recalling information in the amygdale and the hippocampus. Combination treatment has been shown to provide a meaningful correction of stress-induced memory and learning functions.
CONCLUSIONS: These findings indicate that combination treatment may help reduce the stress-induced impairments in cognitive functions.