Tao-Hong-Si-Wu decoction improves depressive symptoms in model rats via amelioration of BDNF-CREB-arginase I axis disorders

Abstract

Context: The traditional Chinese medicine formula Tao-Hong-Si-Wu decoction (TSD), used for treating ischaemic stroke, has the potential to treat depressive disorder (DD).

Objective: To explore the effective targets of TSD on DD animal models.

Materials and methods: Sprague-Dawley (SD) rats were modelled by inducing chronic unpredictable mild stress (CUMS) during 35 days and treated with three dosages of TSD (2.5, 5 and 10 g/kg) or fluoxetine (10 mg/kg) by oral gavage for 14 days. Bodyweight measurements and behavioural tests were performed to observe the effect of TSD on the CUMS animals. A gas chromatography coupled with mass spectrometry (GC-MS)-based metabolomic analysis was conducted to reveal the metabolic characteristics related to the curative effect of TSD. Levels of the proteins associated with the feature metabolites were analysed.

Results: Reduced immobile duration and crossed squares in the behavioural tests were raised by 48.6% and 32.9%, on average, respectively, by TSD treatment (ED₅₀=3.2 g/kg). Antidepressant effects of TSD were associated with 13 decreased metabolites and the restorations of ornithine and urea in the serum. TSD (5 g/kg) raised serum serotonin by 54.1 mg/dL but suppressed arginase I (Arg I) by 47.8 mg/dL in the CUMS rats. Proteins on the brain-derived neurotrophic factor (BDNF)-cAMP response element-binding protein (CREB) axis that modulate the inhibition of Arg I were suppressed in the CUMS rats but reversed by the TSD intervention.

Discussion and conclusions: TSD improves depression-like symptoms in CUMS rats. Further study will focus on the antidepressant-like effects of effective compounds contained in TSD.

Keywords: GC–MS; Metabolomics; depressive disorder; traditional Chinese medicine.

Figure 1.

The comparison of body weight and the findings of behavioural tests before and after dosing of TSD. (a) A schema displaying the process of animal experiments; (b) ED₅₀ of TSD determined by measuring serotonin in another cohort of CUMS rats. Sixty percent increased serotonin in the rat serum is considered as desired response after pharmaceutical treatments. (c) Bodyweight changes along with the TSD dosing for the groups of rats; (d) the total immobile time of rats recorded in the forced swimming test; (e–g) grooming times, rearing times, and numbers of crossed squares recorded in the open field test, respectively. *Significance between the treated and non-treated CUMS rats; ^#significance between the model and common rats; *^/#p < 0.05; ***^/###p < 0.001.

Figure 2.

Score plots of PCA and OPLS-DA for the separations of serum metabolome between different groups of rats. (a, b) Score plot of PCA and OPLS-DA for the separations between the CUMS model group and the blank group; (c) a PCA showing the separation between the CUMS model group and the CUMS rats treated with different dosages of TSD. (d) OPLS-DA showing the separation between CUMS model rats and the integration of TSD-treated rats. B: The blank group; M: the model group; TL: the model animals treated with a low dose of TSD; TM: model animals treated with a medium dose of TSD; TH: rats treated with a high dose of TSD (the same indications are used below); T: TSD-intervened group.

Figure 3.

Metabolites with different characteristics between groups of serum metabolism of rats. FX: CUMS rats treated with fluoxetine. (a) A Venn diagram showing the differential metabolites associated with CUMS modelling and with the effect of TSD. Metabolites encompassed within the left oval: characteristic metabolites involved in the CUMS modelling; metabolites encompassed within the right oval: feature metabolites linked to the effect of TSD on CUMS rats; metabolites included the intersection of the two ovals represent the key metabolites contribute to both the differential analyses; (b–p) key discriminant metabolites that varied both in the comparison between B vs. M and M vs. TSD, a.u.: arbitrary unit; l-Ala: l-alanine; l-Pro: l-proline; l-orn: l-ornithine; l-Tyr: l-tyrosine; l-Gly: l-glycine; l-Glu: l-Phe: l-phenylalanine; 3-AIBA: 3-aminoisobutyric acid; 3-HB: 3-hydroxybutyric acid; l-Glu: l-glutamic acid; l-Ser: l-serine; l-Val: l-valine; l-HP: l-hydroxyproline; d-GFO: β-d-galactofuranoside; BAA: benzeneacetic acid; 1-PSPA: 1-palmitoyllysophosphatidic acid; (q, r) pathway analyses showing the primarily varied metabolic pathways involving the CUMS modelling and the TSD effect, respectively; (q) metabolic pathway analyses for the comparison of B vs. M; (r) metabolic pathway analysis for the comparison between the model group and the integrated groups of rats treated with TSD.

Figure 4.

Measurements of serotonin, Arg I and their related metabolites in different groups. (a) Serum level of arginase I; (b) serum level of serotonin; (c) hippocampal levels of serotonin, Arg I, glycine, urea and ornithine in the groups of rats. The indicators */**/*** stand for the significance by the comparison between the medicine-treated group and the non-treated group; the indicators #/##/### represent significant variations between the model group and the control; *^/#p < 0.05; **^/##p < 0.01; ***^/###p < 0.001; NS: non significant.

Figure 5.

The effect of TSD on the expressions of upstream proteins of Arg I. (a) Targeted hippocampus protein expressions comprised in the BDNF/ERK/CREB signalling. (b) Summary schema of determined varied metabolites and proteins involved in the BDNF-CREB-Arg I axis. Arg I is the enzyme that catalyses the conversion from arginine to ornithine and urea. The transcription of Arg I is regulated by the expression of CREB, which is downstream of serotonin/BDNF/TrkB signalling. The BDNF-CREB-Arg I axis is downregulated after the induction of CUMS modelling and can be reversed by TSD administration.