DataSheet1_Niuhuang Qingxin Wan ameliorates depressive-like behaviors and improves hippocampal neurogenesis through modulating TrkB/ERK/CREB signaling pathway in chronic restraint stress or corticosterone challenge mice.docx

Introduction: Chronic stress-associated hormonal imbalance impairs hippocampal neurogenesis, contributing to depressive and anxiety behaviors. Targeting neurogenesis is thus a promising antidepressant therapeutic strategy. Niuhuang Qingxin Wan (NHQXW) is an herbal formula for mental disorders in Traditional Chinese Medicine (TCM) practice, but its anti-depressant efficacies and mechanisms remain unverified.Methods: In the present study, we tested the hypothesis that NHQXW could ameliorate depressive-like behaviors and improve hippocampal neurogenesis by modulating the TrkB/ERK/CREB signaling pathway by utilizing two depression mouse models including a chronic restraint stress (CRS) mouse model and a chronic corticosterone (CORT) stress (CCS) induced mouse model. The depression-like mouse models were orally treated with NHQXW whereas fluoxetine was used as the positive control group. We evaluated the effects of NHQXW on depressive- and anxiety-like behaviors and determined the effects of NHQXW on inducing hippocampal neurogenesis.Results: NHQXW treatment significantly ameliorated depressive-like behaviors in those chronic stress mouse models. NHQXW significantly improved hippocampal neurogenesis in the CRS mice and CCS mice. The potential neurogenic mechanism of NHQXW was identified by regulating the expression levels of BDNF, TrkB, p-ERK (T202/T204), p-MEK1/2 (S217/221), and p-CREB (S133) in the hippocampus area of the CCS mice. NHQXW revealed its antidepressant and neurogenic effects that were similar to fluoxetine. Moreover, NHQXW treatment revealed long-term effects on preventing withdrawal-associated rebound symptoms in the CCS mice. Furthermore, in a bioactivity-guided quality control study, liquiritin was identified as one of the bioactive compounds of NHQXW with the bioactivities of neurogenesis-promoting effects.Discussion: Taken together, NHQXW could be a promising TCM formula to attenuate depressive- and anxiety-like behaviors against chronic stress and depression. The underlying anti-depressant mechanisms could be correlated with its neurogenic activities by stimulating the TrkB/ERK/CREB signaling pathway.</p

Effect of carnosine on mitochondria membrane potentials of spleen lymphocytes in restraint-stressed mice.

<p>Spleen lymphocyte samples containing 5×10⁵ cells were stained with rhodamine-123. After incubation and wash, cells were resuspended in PBS. <i>ΔΨm</i> was determined using a flow cytometer. Data represented mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal group is at ^##p<0.01, and from model group at ^*p<0.05, ^**p<0.01.</p

<i>In vitro</i> effect of carnosine on the number of spleen lymphocytes (including NK cells) treated with corticosterone.

<p>Carnosine had no tendency to inhibit the reduction of total lymphocytes (A) and NK cells (B) induced by corticosterone <i>in vitro</i>. Data represented mean ± S.E.M. of triplicate assays. The significance of differences from untreated cells is at ^##p<0.01.</p

<i>In vivo</i> and <i>in vitro</i> effects of carnosine on the proliferative response (stimulation index) of spleen lymphocytes stimulated by ConA.

<p>(A) Carnosine increased ConA-stimulated lymphocyte proliferation <i>in vivo</i>. Data represented mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal is at ^##p<0.01, and from model at ^*p<0.05, ^**p<0.01. (B) Carnosine increased ConA-stimulated lymphocyte proliferation by treatment <i>in vitro</i>. Data represented mean ± S.E.M. of triplicate assays. The significance of differences from normal is at ^##p<0.01, and from model at ^*p<0.05, ^**p<0.01.</p

Effects of carnosine on brain histamine concentration (pmol/g tissue) in restraint-stressed mice.

<p>Brain regions including cerebral cortex, hippocampus and hypothalamus were rapidly dissected and homogenized in PBS containing 3% perchloric acid. Histamine level in brain regions was determined by HPLC-ECD. The results represent mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal group was at</p>##<p>p<0.01, and model group at</p>**<p>p<0.01, as determined by ANOVA analysis.</p

Effect of carnosine on lymphocyte apoptosis confirmed by TUNEL assay.

<p>(A) The TUNEL assay was carried out by One Step TUNEL Apoptosis Assay Kit. The images of TUNEL positive cells were captured by a fluorescence microscope (200×). (B) Quantitative result of TUNEL assay was analyzed. Data represented mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal is at ^##p<0.01, and from model at ^**p<0.01.</p

Effect of carnosine on gene expressions of GR, Bax and Bcl-2 mRNAs in spleen lymphocytes of restraint-stressed mice.

<p>RT-PCR was employed to determine the effect of carnosine on the expression of GR, Bax and Bcl-2 mRNAs. Relative expression values for each target gene were expressed as a ratio of target gene expression level to 18S expression level. Data represented mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal is at ^##p<0.01, and from model at ^*p<0.05, ^**p<0.01.</p

Effect of carnosine on spleen index and spleen lymphocyte number in restraint-stressed mice.

<p>On the 7^th day of the experiment, all mice except normal control were physically restrained in a 50 ml polypropylene centrifuge tube with holes for 18 h. Spleens were collected from mice and weighted. Spleen index was expressed as spleen weight (g) over body weight (g). Spleens were disrupted with a grinder. After debris separation and erythrocytes lysis, spleen lymphocytes were obtained and counted. The results represent mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal group is at</p>##<p>p<0.01, and from model group at</p>*<p>p<0.05,</p>**<p>p<0.01, as determined by ANOVA analysis.</p

Effects of carnosine on NK cell number and cytotoxic activity in spleen lymphocytes of restraint-stressed mice.

<p>Spleen lymphocyte samples containing 1×10⁶ cells were stained with anti-CD3 (FITC)/anti-NK1.1 (PE) antibody to assess the percentage of NK cells (NK⁺CD3⁻) by flow cytometry. NK cell number was calculated according to NK cell percentage and total spleen lymphocyte number. In the determination of NK cell cytotoxic activity, target cells were YAC-1 cells. YAC-1 cells, stained with DiO, were mixed with freshly isolated spleen lymphocytes and incubated. Then PI was added to the mixtures. After incubation, NK cell activity was determined by flow cytometry. The results represent mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal group was at</p>##<p>p<0.01, and model group at</p>*<p>p<0.05,</p>**<p>p<0.01, as determined by ANOVA analysis.</p

Effect of carnosine on cytochrome c (Cyt c) contents in mitochondria and cytoplasm in restraint-stressed mice.

<p>Spleen lymphocytes samples containing (2×10⁶) were gently lysed with lysis buffer. Lysates were centrifuged to obtain supernatants (cytosolic extracts free of mitochondria) and the pellets (fraction that contains mitochondria). These two fractions were adjusted to 2 mg protein/ml in the buffer. Contents of cytochrome c were determined using difference spectra at the wavelength pairs of 550∼535, 554∼540 and 563∼577 respectively. The results represent mean ± S.E.M. obtained from 10 animals in each group. The significance of differences from normal group is at</p>##<p>p<0.01, and from model group at</p>*<p>p<0.05,</p>**<p>p<0.01, as determined by ANOVA analysis.</p