Liquid chromatography-mass spectrometry-based urinary metabolomics study on a rat model of simulated microgravity-induced depression.

The pathophysiological mechanism of depression is complex and its etiology remains unclear. Metabolomics can be used to monitor multiple metabolic pathways simultaneously, thereby investigating the mechanisms of depression onset and its regulation. Therefore, we studied the metabolic profile of urine samples from a rat model of depression for identifying potential metabolic biomarkers associated with depression. The depression model of rats was induced by 14-d simulated microgravity (SMG) treatment. Principal component analysis and orthogonal partial least squares discriminate analysis were performed to classify and identify the differences of endogenous metabolites in urine between the normal and depressed rats. Multivariate statistical analysis revealed distinct separation between the urinary metabolic profiles of SMG-treated and control rats. Citric acid, oxalosuccinic acid, creatine, proline, cyclic AMP, L-dihydroxyphenylalanine (DOPA), phenylacetylglycine, 5-hydroxyindole acetaldehyde, succinylcholine, deoxyuridine, 3-hydroxyhippuric acid, glutamine, and 5-hydroxytryptophan levels were significantly reduced, whereas indole-3-acetaldehyde, xanthurenic acid, taurine, kynurenic acid, hippuric acid, 5-hydroxyindoleacetic acid, 2-phenylethanol glucuronide, 2-isopropyl-3-oxosuccinate, and adrenaline levels were elevated significantly in model group. These biochemical changes were related to tryptophan, arginine, proline, and phenylalanine metabolism, and perturbations in energy metabolism. These details of depression will be helpful to the clinical diagnosis of depression caused by space and gravity.

Antidepressant effects of dammarane sapogenins in chronic unpredictable mild stress-induced depressive mice.

Depression is a common, dysthymic, and psychiatric disorder, resulting in enormous social and economic burden. Dammarane sapogenins (DS), an active fraction from oriental ginseng, has shown antidepressant-like effects in chronic restraint rats and sleep interruption-induced mice, and the present study aimed to further confirm the antidepressant effects of DS in a model of chronic unpredictable mild stress (CUMS) and to explore the underlying mechanism. Oral administration of DS (20, 40, and 80 mg/kg) markedly improved depressant-like behaviors, increasing the sucrose intake in the sucrose preference test and reducing the latency in the novelty-suppressed feeding test, and decreasing the immobility time in both the tail suspension and forced swimming tests, compared with the CUMS mice. Biochemical analysis of brain tissue and serum showed that DS treatment restored the decreased hippocampal neurotransmitter concentrations of serotonin, dopamine, norepinephrine (noradrenaline), and gamma-aminobutyric acid, and decreased the elevated of serum hormone levels (corticotrophin releasing factor, adrenocorticotrophic hormone, and corticosterone) induced by CUMS. Our findings confirm that DS exerts an antidepressant-like effect in the CUMS model of depression in mice, and suggest it may be mediated by regulation of neurotransmitters and hypothalamic-pituitary-adrenal axis.

[Antidepressant effects of the extract of Dendrobium nobile Lindl on chronic unpredictable mild stress-induced depressive mice].

To investigate whether the extract of Dendrobium nobile Lindl (DNL) has an antidepressant effect on chronic unpredictable mild stress (CUMS)-induced depressive mice, 72 BALB/c male mice were randomly divided into the control group, the CUMS model group, the extract of DNL groups (50, 100 and 200 mg/kg DNL, i.g.) and the paroxetine group (10 mg/kg, i.g.). The different doses of DNL or the paroxetine was administered orally once daily to CUMS mice for 8 weeks (containing two-week preventive medication before the modeling). The same volume of distilled water was given to the control group and the CUMS group. Except for the control group, the other mice were exposed to chronic stress for 35 days. Behavioral tests were performed by using the sucrose preference test (SPT), the novelty-suppressed feeding (NSF) test, the tail suspension test (TST), and the forced swim test (FST). The levels of dopamine (DA) and 5-hydroxytryptamine (5-HT) were measured by the liquid chromatography-mass spectrometer (LC-MS)/MS. Compared with the control group, obvious behavioral changes were observed in the CUMS group after 5-week CUMS, including a decrease in the sucrose consumption, an increase in the latency to feeding in the NSF test and a prolongation of the immobility time in the TST. Compared with the CUMS group, the application of DNL resulted in a dose-dependent increase in sucrose consumption (P < 0.01) as paroxetine (10 mg/kg) did and a significant dose-dependent decrease in the latency to feeding in the NSF test (P < 0.05). In the TST, the application of paroxetine (10 mg/kg) and the high-dose DNL (200 mg/kg) obviously decreased the immobility time when compared with the CUMS group (P < 0.05). In the FST, compared with the CUMS group, all the groups had no significant differences in the immobility time (P > 0.05). In addition, in the hippocampus and cortex, the levels of 5-HT and DA were significantly decreased in the CUMS group compared with the control group (P < 0.05). In comparison with the CUMS group, paroxetine obviously increased the DA levels in the hippocampus and the cortex and the 5-HT level in the hippocampus (P < 0.05). DNL (50 and 200 mg/kg) significantly increased the DA level in cerebral cortex of the brain, and DNL (100 and 200 mg/kg) increased the DA level in the hippocampus. The 5-HT level in the 200 mg/kg DNL group was notably increased in both two brain regions (P < 0.05), but the 5-HT level in the 100 mg/kg DNL group was significantly increased only in the hippocampus (P < 0.01). These findings indicate that the extract of DNL has an antidepressant-like effect on CUMS-induced depressive mice and its mechanism may be related to the changes in DA and 5-HT in the hippocampus and cortex.