Cinnamomum zeylanicum extract has antidepressant-like effects by increasing brain-derived neurotrophic factor (BDNF) and its receptor in prefrontal cortex of rats

Abstract

Objective: Depression is one of the most common mood disorders. Considering the evidence on the effect of Cinnamomum on mood disorders, this study investigatedthe effect of hydroalcoholic extract of Cinnamomum (HEC) in an animal model of depression.

Materials and methods: Thirty-two male rats were selected and divided into four groups (n=8) including: control, depressed, and depressed treated with200 and 400 mg/kg HEC. Depression induction protocol was conducted in all groups except for the control group. Sucrose preference test (SPT) and forced swimming test (FST) were done to analyze the depression score. After four weeks, the animals brain cortex was removed and BDNF protein and tyrosine receptor kinase B (TrkB) gene expression levels were determined by ELISA and Real Time PCR, respectively.

Results: The results of this study showed that 400 mg/kg of HEC increased the tendency to drink the sucrose solution. Furthermore, immobility time significantly increased in the depressed group compared to the control group while it was attenuated by administration of 400 mg/kg extract on the 28th day versus the depressed group. Also the extract at both doses increased swimming time compared to the depressed group. In addition, an increase in the BDNF protein and TrkB gene expression levels was observed in the prefrontal cortex of the treatment groups.

Conclusion: We found that HEC ameliorated depression symptoms in rats and these effects were probably due to an increase in BDNF proteins and its receptor, TrkB, gene expressions in the prefrontal cortex.

Keywords: Depression; Gene expression; Hydroalcoholic extract of Cinnamomum; Mood disorders; Receptor tyrosine kinases.

Figure 1

The SPT in control, depressed and Dep +HEC 200 and Dep +HEC 400 groups. Each marker is representing the mean±SEM for 8 rats. *p<0.05, **p<0.01 and ***p<0.001 show significant differences compared to the control group. +p<0.05, ++p<0.01 and ⁺⁺⁺p<0.001 show significant differences within groups compared to the base. ^p<0.05 shows significant differences compared to the depressed group. Dep=depressed, HEC=hydroalcoholic extract of Cinnamomum, SPT=Sucrose preference test

Figure 2

The swimming time index in the FST in the control, depressed and Dep +HEC 200 and Dep +HEC 400 groups. Each column is representing the mean±SEM for 8 rats. **p<0.01 shows significant differences compared to the control group. +p<0.05 and ++p<0.01 show significant differences within groups compared to the base. ^p<0.05 shows significant differences compared to the depressed group. Dep=depressed, HEC=hydroalcoholic extract of Cinnamomum

Figure 3

The immobility time index in the FST in the control, depressed and Dep +HEC 200 and Dep +HEC 400 groups. Each column is representing the mean±SEM for 8 rats. **p<0.01 and ***p<0.001 show significant differences compared to the control group. +p<0.05, ++p<0.01 and ⁺⁺⁺p<0.001 show significant differences within groups compared to the base. ^p<0.05 shows significant differences compared with the depressed group. Dep=depressed, HEC=hydroalcoholic extract of Cinnamomum

Figure 4

The BDNF protein level in the prefrontal cortex of the control, depressed and Dep +HEC 200 and Dep +HEC 400 groups. Each column represents the mean±SEM for 8 rats. ***p<0.001showsdifferences compared to the control group. ⁺⁺⁺p<0.001 shows significant differences compared to the depressed group. Dep=depressed, HEC=hydroalcoholic extract of Cinnamomum

Figure 5

The TrkB gene expression ratio in the prefrontal cortex of the control, depressed and Dep +HEC 200 and Dep +HEC 400 groups. Each column represents the mean±SEM for 8 rats. ***p<0.001 shows significant differences compared to the control group. +p<0.05 and+++p<0.001 show significant differences compared to the depressed group. Dep=depressed, HEC=hydroalcoholic extract of Cinnamomum