Elsevier

Journal of Ethnopharmacology

Volume 208, 17 August 2017, Pages 94-104
Journal of Ethnopharmacology

Xiaochaihutang attenuates depressive/anxiety-like behaviors of social isolation-reared mice by regulating monoaminergic system, neurogenesis and BDNF expression

https://doi.org/10.1016/j.jep.2017.07.005Get rights and content

Abstract

Ethnopharmacological relevance

Xiaochaihutang (XCHT), as a classical herbal formula for the treatment of “Shaoyang syndrome” has been demonstrated to exert an antidepressant effect in multiple animal models of depression as shown in our previous studies. However, the effects of XCHT on social isolation (SI)-reared mice have not been investigated. This study aims to explore the effects of XCHT on depressive/anxiety-like behaviors of SI-reared mice, and its implicated mechanisms, including alterations in the monoaminergic system, neurogenesis and neurotrophin expression.

Materials and methods

Male C57 BL/6 J mice (aged 4 weeks after weaning) were reared isolatedly for 8 weeks and XCHT (0.8, 2.3, 7.0 g/kg) were given by gavage once a day. Forced swimming test (FST), tail suspension test (TST), open field test (OFT), elevated-plus maze test (EPM) and intruder-induced aggression test were used to explore the effects of XCHT on depressive/anxiety-like behaviors of SI-reared mice after administration of XCHT for 6 weeks. HPLC-MS/MS was performed to quantify the levels of neurotransmitters in the hippocampus by in vivo microdialysis, while western immunoblotting was used to evaluate the action of XCHT on the synthesis, transport and degradation of monoamine neurotransmitters. Immunofluorescence was used to study the effects of XCHT on neurogenesis and neurotrophin expression, including Ki-67, DCX, BrdU and BDNF.

Results

Our results showed that administration of XCHT (0.8, 2.3 and 7.0 g/kg) for 6 weeks significantly attenuated the increase in immobility time in TST and FST, improved the anxiety-like behaviors in OFT and EPM, and improved the aggressive behaviors of SI-reared mice. XCHT significantly elevated monoamine neurotransmitters levels and inhibited 5-HT turnover (5-HIAA/5-HT) in hippocampal microdialysates of SI-reared mice. In addition, we found XCHT enhanced monoamine neurotransmitter synthesis enzymes (TPH2 and TH) expressions, inhibited serotonin transporter (SERT) expression and decreased monoamine neurotransmitter degradation enzyme (MAOA) expression in the hippocampus of SI-reared mice for the first time. Moreover, XCHT significantly augmented hippocampal neurogenesis and BDNF expression in hippocampus of SI-reared mice.

Conclusions

Our results showed for the first time that XCHT improved depressive/anxiety-like behaviors of SI-reared mice by regulating the monoaminergic system, neurogenesis and neurotrophin expression. The findings indicate that XCHT may have a therapeutic application for early-life stress model of depression and in turn provide further evidence supporting XCHT a novel potential antidepressant from a distinct perspective.

Introduction

The social isolation (SI) rearing model is commonly considered as an early life stressor in animals, where post-weaning animals are raised in single-housed conditions (Fone and Porkess, 2008, Yorgason et al., 2016). It is often used to model childhood neglect leading to behavioral changes indicative of depression/anxiety in adulthood. These behavioral changes include hyper-locomotor activity under a novel environment (Koponen et al., 1989), raised anxiety-like performance, increased despair statement and aggressive behaviors (Koike et al., 2009, Kokare et al., 2010), which are similar to those observed in depressive individuals with early life stress. SI has been known to significantly influence the adult brain function, such as the activity of monoaminergic system, hippocampal neurogenesis and neurotrophin expression (Ibi et al., 2008, Lukkes et al., 2009).

Xiaochaihutang (XCHT) is a classic Chinese herbal formula for the treatment of “Shaoyang syndrome”, which is recorded in “ShangHan Lun” written by Zhang Zhongjing (150–219 A.D.) of the Chinese Eastern Han Dynasty. It has been reported that XCHT could treat clinical depressive disorders (Jia et al., 2009, Li and Gao, 1996). Our previous studies suggested that XCHT exerted antidepressant effects in the forced swimming test, tail suspension test and improved depressive-like behaviors in model of chronic unpredictable mild stress and neuroendocrine model of anxiety/depression (Su et al., 2014a, Zhang et al., 2015, Zhang et al., 2016). Furthermore, we demonstrated that XCHT could regulate depressive/anxiety-like behaviors of adult rats induced by social isolation stress (Ma et al., 2016).

The monoamine deficiency hypothesis proposes that depressive symptoms arise from the deficiency of monoamine neurotransmitters, such as 5-HT, NE, and/or DA (Delgado, 2000). The monoaminergic system is mostly implicated in the pathophysiology of depression and in the mechanisms of antidepressants therapy. Studies have discovered that agents altering monoamine metabolism, such as serotonin (5-hydroxytryptamine, 5-HT), norepinephrine (NE) and dopamine (DA) relieve depressive symptoms. At present, monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), NE reuptake inhibitors (NRIs) and the dual reuptake inhibitors (SNRIs) are commonly used for the treatment of depression. Our previous study found that XCHT could alter monoamine neurotransmitter levels in several brain regions (Su et al., 2014b), but XCHT's effects in altering the synthesis, transport and degradation of monoamine neurotransmitters have never been investigated. In addition, neurotrophic factors and adult neurogenesis have been shown to mediate the behavioral responses to antidepressants. The brain-derived neurotropic factor (BDNF) is regulated by antidepressants and is associated with antidepressant-like behavioral response in animal models of depression (Duman and Monteggia, 2006, Monteggia et al., 2004). Neurogenesis is also considered to modulate hippocampal function to produce antidepressant effects (Sahay and Hen, 2007). Our group has demonstrated that XCHT promoted hippocampal neurogenesis of non-stressed mice and depressive animals including socially isolated adult rats and depressive mice exposed to chronic corticosterone stress. Yet, it is still unknown whether neurotrophic factors and adult neurogenesis are underlying mechanisms that mediate XCHT's regulation on depressive/anxiety-related behaviors of SI-reared mice.

Therefore, in order to further evaluate the antidepressant effect of XCHT and the possible mechanism of action from distinct perspectives, we adopted social isolation-reared mice model of depression to investigate the consequences of XCHT on depressive/anxiety-related behaviors and elucidate the potential neurobiological mechanisms underlying these changes by investigating monoaminergic system, neurogenesis and neurotrophin expression in hippocampus.

Section snippets

Drugs

XCHT is an herbal formula comprising seven drugs (Su et al., 2014a, Wu et al., 2015): Radix Bupleuri (12 g; Latin name: Bupleurum chinense DC.; no. 1012002), Radix Scutellariae (9 g; Latin name: Scutellaria baicalensis Georgi; no. 1101002), Ginseng (9 g; Latin name: Panax ginseng C.A. Meyer; no. 20111001), Rhizoma Pinelliae (9 g; [Latin name: Pinellia ternata (Thunb.) Breit.]; no. 110303), Radix Glycyrrhizae (6 g; Latin name: Glycyrrhiza uralensis Fisch.; no. 1101002), Rhizoma Zingiberis recens (6 g;

XCHT alleviates depressive-like behaviors of SI-reared mice

Depressive-like behaviors were tested in TST and FST. Fig. 2 shows that the immobility time of social isolation-reared mice was significantly increased compared with the control group in TST and FST (P < 0.01 and P < 0.05, respectively). Treatment with XCHT (7.0 g/kg) for 6 weeks significantly reduced the immobility time in TST compared with SI group (P < 0.05). Similarly, XCHT (2.3 g/kg) administration significantly shortened the prolonged immobility time in FST that was induced by post-weaning

Discussion

In this study, we found that SI-reared mice exhibited a higher level of spontaneous locomotor activity, a longer duration of immobility in the TST and FST, decreased time spent in open arms of the EPM test and enhanced aggressive behaviors, of which these behavioral alternations were significantly reversed after XCHT treatment, suggesting that XCHT could remarkably alleviate depressive/anxiety-related behaviors of post-weaning mice resulting from chronic social isolation stress.

The

Conclusion

Our study demonstrated that chronic social isolation stress after weaning produced profound depressive/anxiety-like behaviors with decreased function in the monoaminergic system and decreases in neurogenesis/neurotrophin-associated proteins expression. XCHT attenuated depressive/anxiety-like behaviors of social isolation-reared mice, and the plausible neurobiological mechanism underlying these behavioral changes may be related to improving the monoaminergic activity, neurogenesis and

Conflicts of interest

The authors declare no conflict of interest.

Acknowledgments

This research was supported by the Key Project of National Natural Science Foundation of China, P.R. China (81130071), the Project of Innovation Team of Liaoning of P.R. China (LT2013021) and Doctoral Scientific Research Foundation of Liaoning Province (2013010582-401).

References (43)

  • C. Lieberwirth et al.

    Social isolation impairs adult neurogenesis in the limbic system and alters behaviors in female prairie voles

    Horm. Behav.

    (2012)
  • L. Lu et al.

    Modification of hippocampal neurogenesis and neuroplasticity by social environments

    Exp. Neurol.

    (2003)
  • I. Mahar et al.

    Stress, serotonin, and hippocampal neurogenesis in relation to depression and antidepressant effects

    Neurosci. Biobehav. Rev.

    (2014)
  • H. Scharfman et al.

    Increased neurogenesis and the ectopic granule cells after intrahippocampal BDNF infusion in adult rats

    Exp. Neurol.

    (2005)
  • G.Y. Su et al.

    Antidepressant-like effects of Xiaochaihutang in a rat model of chronic unpredictable mild stress

    J. Ethnopharmacol.

    (2014)
  • H.N. Wang et al.

    Anti-depressive mechanism of repetitive transcranial magnetic stimulation in rat: the role of the endocannabinoid system

    J. Psychiatr. Res.

    (2014)
  • P. Willner et al.

    The neurobiology of depression and antidepressant action

    Neurosci. Biobehav. Rev.

    (2013)
  • J.T. Yorgason et al.

    Social isolation rearing increases dopamine uptake and psychostimulant potency in the striatum

    Neuropharmacology

    (2016)
  • K. Zhang et al.

    Analysis of main constituents and mechanisms underlying antidepressant-like effects of Xiaochaihutang in mice

    J. Ethnopharmacol.

    (2015)
  • K. Zhang et al.

    Antidepressant-like effects of Xiaochaihutang in a neuroendocrine mouse model of anxiety/depression

    J. Ethnopharmacol.

    (2016)
  • M. Banasr et al.

    Serotonin-induced increases in adult cell proliferation and neurogenesis are mediated through different and common 5-HT receptor subtypes in the dentate gyrus and the subventricular zone

    Neuropsychopharmacol.: Off. Publ. Am. Coll. Neuropsychopharmacol.

    (2004)
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