OBJECTIVE To observe the changes in brain function characteristics of Chaihu Tongbian Decoction in rats with slow transit constipation (STC) and depression using resting-state functional magnetic resonance imaging (rs-fMRI).
METHODS 70 healthy SPF grade male SD rats were randomly divided into the blank group, model group, mosapride group, fluoxetine hydrochloride group, low (11.02 g·kg-1), medium (22.05 g·kg-1), and high (44.1 g·kg-1) dose Chaihu Tongbian Decoction groups. A rat model of STC with depression was constructed using compound diphenylephrine tablets combined with solitary confinement and chronic unpredictable mild stress (CUMS). Drugs were administered after successful modeling. The general condition of the rats was observed; 24 h total number of fecal particles, fecal water content and intestinal carbon end advance rate were calculated; HE staining of the colon tissue was performed; the depressive-like behavior of the rats was detected. By comparing rs-fMRI amplitude of low-frequency fluctuation (ALFF) values, the differences in neuronal activity in the brains of rats in each group were explored.
RESULTS Compared with the blank group, the 24 h total number of fecal particles, fecal water content and intestinal carbon end advance rate in the model group were significantly reduced (P < 0.01). HE staining showed that the colon tissue lesions in the model group were severe. Open field experiment and sugar water consumption showed that the activity level of rats in the model group decreased (P < 0.01), and behavioral changes like anxiety and depression appeared. The rs-fMRI results showed that compared with the blank group, the ALFF value of the right posterolateral hippocampus in the model group decreased and the ALFF value of the left amygdala increased (P < 0.01). Compared with the model group, after 4 weeks of treatment, the 24 h total number of fecal particles, fecal water content, and intestinal carbon end advance rate in the mosapride group and each dose group of Chaihu Tongbian Decoction were improved (P < 0.05); compared with the model group, after 4 weeks of treatment, the fluoxetine hydrochloride group and each dose group of Chaihu Tongbian Decoction could improve the anxiety and depression-like behavior of rats (P < 0.05); compared with the model group, after 4 weeks of treatment, the fluoxetine hydrochloride group and the high-dose Chaihu Tongbian Decoction group could increase the ALFF value of the right posterolateral hippocampus and decrease the ALFF value of the left amygdala (P < 0.05).
CONCLUSION Chaihu Tongbian Decoction can effectively relieve constipation and depressive symptoms in STC rats with depression, and its mechanism may be related to activating the right posterolateral hippocampus and inhibiting amygdala activity.
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