Apocynum venetum Leaf Extract Exerts Antidepressant-Like Effects and Inhibits Hippocampal and Cortical Apoptosis of Rats Exposed to Chronic Unpredictable Mild Stress

Comparing the effect of fluoxetine, escitalopram, and sertraline, on the level of BDNF and depression in preclinical and clinical studies: a systematic review

Brain-derived neurotrophic factor (BDNF) dysfunction is one of the most important mechanisms underlying depression. It seems that selective serotonin reuptake inhibitors (SSRIs) improve depression via affecting BDNF level. In this systematic review, for the first time, we aimed to review the effect of three SSRIs including fluoxetine, escitalopram, and sertraline, on both depression and BDNF level in preclinical and clinical studies. PubMed electronic database was searched, and 193 articles were included in this study. After reviewing all manuscripts, only one important difference was found: subjects. We found that SSRIs induce different effects in animals vs. humans. Preclinical studies showed many controversial effects, while human studies showed only two effects: improvement of depression, with or without the improvement of BDNF. However, most studies used chronic SSRIs treatment, while acute SSRIs were not effectively used and evaluated. In conclusion, it seems that SSRIs are reliable antidepressants, and the improvement effect of SSRIs on depression is not dependent to BDNF level (at least in human studies).

Neuroprotective Role of Selenium Nanoparticles Against Behavioral, Neurobiochemical and Histological Alterations in Rats Subjected to Chronic Restraint Stress

Chronic stress induces changes in the prefrontal cortex and hippocampus. Selenium nanoparticles (SeNPs) showed promising results in several neurological animal models. The implementation of SeNPs in chronic restraint stress (CRS) remains to be elucidated. This study was done to determine the possible protective effects of selenium nanoparticles on behavioral changes and brain oxidative stress markers in a rat model of CRS. 50 rats were divided into three groups; control group (n = 10), untreated CRS group (n = 10) and CRS-SeNPs treated group (n = 30). Restraint stress was performed 6 h./day for 21 days. Rats of CRS-SeNPs treated group received 1, 2.5 or 5 mg/kg SeNPs (10 rats each) by oral gavage for 21 days. Rats were subjected to behavioral assessments and then sacrificed for biochemical and histological analysis of the prefrontal cortex and hippocampus. Prefrontal cortical and hippocampal serotonin levels, oxidative stress markers including malondialdehyde (MDA), reduced glutathione (GSH) and glutathione peroxidase (GPx), tumor necrosis factor alpha (TNF-α) and caspase-3 were assessed. Accordingly, different doses of SeNPs showed variable effectiveness in ameliorating disease parameters, with 2.5 mg/kg dose of SeNPs showing the best improving results in all studied parameters. The present study exhibited the neuroprotective role of SeNPs in rats subjected to CRS and proposed their antioxidant, anti-inflammatory and anti-apoptotic effects as the possible mechanism for increased prefrontal cortical and hippocampal serotonin level, ameliorated anxiety-like and depressive-like behaviors and improved prefrontal cortical and hippocampal histological architecture.

Therapeutic effects of astragaloside IV and Astragalus spinosus saponins against bisphenol A-induced neurotoxicity and DNA damage in rats

Background

Bisphenol A (BPA) is an endocrine disruptor to which humans are often subjected during daily life. This study aimed to investigate the ameliorative effect of astragaloside IV (ASIV) or saponins extracted from Astragalus spinosus (A. spinosus) against DNA damage and neurotoxic effects induced by BPA in prefrontal cortex (PFC), hippocampal and striatal brain regions of developing male rats.

Materials and Methods

Juvenile PND20 (pre-weaning; age of 20 days) male Sprague Dawley rats were randomly and equally divided into four groups: control, BPA, BPA+ASIV and BPA+A. spinosus saponins groups. Bisphenol A (125 mg/kg/day) was administrated orally to male rats from day 20 (BPA group) and along with ASIV (80 mg/kg/day) (BPA+ASIV group) or A. spinosus saponin (100 mg/kg/day) (BPA+ A. spinosus saponins group) from day 50 to adult age day 117.

Results

Increased level of nitric oxide (NO) and decreased level of glutamate (Glu), glutamine (Gln), glutaminase (GA) and glutamine synthetase (GS) were observed in the brain regions of BPA treated rats compared with the control. On the other hand, co-administration of ASIV or A. spinosus saponin with BPA considerably improved levels of these neurochemicals. The current study also revealed restoration of the level of brain derived neurotrophic factor (BDNF) and N-methyl-D-aspartate receptors (NR₂A and NR₂B) gene expression in BPA+ ASIV and BPA+A. spinosus saponins groups. The co-treatment of BPA group with ASIV or A. spinosus saponin significantly reduced the values of comet parameters as well as the intensity of estrogen receptors (ERs) immunoreactive cells and improved the histological alterations induced by BPA in different brain regions.

Conclusion

It could be concluded that ASIV or A. spinosus saponins has a promising role in modulating the neurotoxicity and DNA damage elicited by BPA.

Optimization of food deprivation and sucrose preference test in SD rat model undergoing chronic unpredictable mild stress

BACKGROUND

The chronic unpredictable mild stress (CUMS) model has long been considered the best model for exploring the pathophysiological mechanisms underlying depression. However, there are no widely recognised standards for strategies for modeling and for behavioral testing. The present study aimed to optimize the protocols for food deprivation and the sucrose preference test (SPT) for the CUMS model.

METHODS

We first evaluated the effects of different long periods of food deprivation on the body weight of Sprague Dawley (SD) rats by testing food deprivation for 24 hours (8:00-8:00+), food deprivation for 12 hours during the daytime (8:00-20:00) and food deprivation for 12 hours at night (20:00-8:00+). Next, we established a SD rat CUMS model with 15 different stimulations, and used body weight measurement, SPT, forced swim test (FST), open field test (OFT) and Morris water maze (MWM) test to verify the success of the modeling. In the SPT, consumption of sucrose and pure water within 1 and 12 hours was measured.

RESULTS

Twelve hours of food deprivation during the daytime (8:00-20:00) had no effect on body weight, while 12 hours of food deprivation at night (20:00-8:00+) and 24 hours of food deprivation (8:00-8:00+) significantly reduced the mean body weight of the SD rats. When SPT was used to verify the successful establishment of the CUMS rat model, sucrose consumption measured within 12 hours was less variable than that measured within 1 hour.

CONCLUSIONS

Twelve hours of food deprivation in the daytime (8:00-20:00) may be considered a mild stimulus for the establishment of a CUMS rat model. Measuring sucrose consumption over 12 hours is recommended for SPT.

Genomic Survey, Transcriptome, and Metabolome Analysis of Apocynum venetum and Apocynum hendersonii to Reveal Major Flavonoid Biosynthesis Pathways

Apocynum plants, especially A. venetum and A. hendersonii, are rich in flavonoids. In the present study, a whole genome survey of the two species was initially carried out to optimize the flavonoid biosynthesis-correlated gene mining. Then, the metabolome and transcriptome analyses were combined to elucidate the flavonoid biosynthesis pathways. Both species have small genome sizes of 232.80 Mb (A. venetum) and 233.74 Mb (A. hendersonii) and showed similar metabolite profiles with flavonols being the main differentiated flavonoids between the two specie. Positive correlation of gene expression levels (flavonone-3 hydroxylase, anthocyanidin reductase, and flavonoid 3-O-glucosyltransferase) and total flavonoid content were observed. The contents of quercitrin, hyperoside, and total anthocyanin in A. venetum were found to be much higher than in A. hendersonii, and such was thought to be the reason for the morphological difference in color of A. venetum and A. hendersonii. This study provides valuable genomic and metabolome information for understanding of A. venetum and A. hendersonii, and lays a foundation for elucidating Apocynum genus plant flavonoid biosynthesis.

Hippocampus-specific regulation of long non-coding RNA and mRNA expression in germ-free mice

Gut microbiota can affect multiple brain functions and cause behavioral alterations through the microbiota-gut-brain axis. In our previous study, we found that the absence of gut microbiota can influence the expression of microRNAs and mRNAs in the hippocampal region of the germ-free (GF) mice. Long non-coding RNAs (lncRNAs) are increasingly being recognized as an important functional transcriptional regulator in the brain. In the present study, we aim to identify possible biological pathways and functional networks for lncRNA-associated transcript of the gut microbiota in relation to the brain function. The profiles of lncRNA and mRNA from specific pathogen-free (SPF), colonized GF (CGF), and GF mice were generated using the Agilent Mouse LncRNA Array v2.0. Differentially expressed (DE) lncRNAs and mRNAs were identified, and lncRNA target genes were also predicted. Ingenuity pathway analysis (IPA) was performed to analyze related signaling pathways and biological functions associated with these dysregulated mRNAs and target genes. Validation with quantitative real-time PCR was performed on several key genes. Compared with SPF mice a total of 2230 DE lncRNAs were found in GF mice. Among these, 1355 were upregulated and 875 were downregulated. After comparing the target genes of DE lncRNAs with mRNA datasets, 669 overlapping genes were identified. IPA core analyses revealed that most of these genes were highly associated with cardiac hypertrophy, nuclear factors of activated T cells (NFAT) gonadotropin-releasing hormone (GnRH), calcium, and cAMP-response element-binding protein (CREB) signaling pathways. Additionally, mRNA expression levels of APP, CASP9, IGFBP2, PTGDS, and TGFBR2 genes that are involved in central nervous system functions were significantly changed in the GF mouse hippocampus. Through this study, for the first time, we describe the effect of gut microbiota on the hippocampal lncRNA regulation. This will help in enhancing the overall knowledge about microbiota-gut-brain axis.