Sodium propionate oral supplementation ameliorates depressive-like behavior through gut microbiome and histone 3 epigenetic regulation.

Major depressive disorder (MDD) is a global health concern, affecting over 250 million individuals worldwide. In recent years, the gut-brain axis has emerged as a promising field for understanding the pathophysiology of MDD. Microbial metabolites, such as short-chain fatty acids (SCFAs)-acetate, butyrate, and propionate-, have gained attention for their potential to influence epigenetic modifications within the host brain. However, the precise mechanisms through which these metabolites participate in MDD pathophysiology remain elusive. This study was designed to investigate the effects of oral SCFA supplementation in adult male Wistar rats subjected to chronic unpredictable mild stress (CUMS). A subset of control and CUMS-exposed rats received different supplementations: sodium acetate (NaOAc) at a concentration of 60 mM, sodium butyrate (NaB) at 40 mM, sodium propionate (NaP) at 50 mM, or a mixture of these SCFAs. The gut microbiome was assessed through 16S rRNA sequencing, and epigenetic profiling was performed using Western blot analysis. Results demonstrated that NaP supplementation significantly alleviated anhedonia in stressed animals, as evidenced by improved performance in the sucrose consumption test. This ameliorative effect was potentially associated with the modulation of gut bacterial communities, accompanied by the attenuation of the region-specific epigenetic dysregulation in the brain of the animals exposed to chronic stress. These findings suggest a potential association between gut dysbiosis and stress response, and NaP could be a promising target for future MDD interventions. However, further studies are needed to fully elucidate the underlying mechanisms of these effects.

Histone 3 Trimethylation Patterns are Associated with Resilience or Stress Susceptibility in a Rat Model of Major Depression Disorder.

Major Depressive Disorder (MDD) is a severe and multifactorial psychiatric condition. Evidence has shown that environmental factors, such as stress, significantly explain MDD pathophysiology. Studies have hypothesized that changes in histone methylation patterns are involved in impaired glutamatergic signaling. Based on this scenario, this study aims to investigate histone 3 involvement in depression susceptibility or resilience in MDD pathophysiology by investigating cellular and molecular parameters related to i) glutamatergic neurotransmission, ii) astrocytic functioning, and iii) neurogenesis. For this, we subjected male Wistar rats to the Chronic Unpredictable Mild Stress (CUMS) model of depression. We propose that by evaluating the sucrose consumption, open field, and object recognition test performance from animals submitted to CUMS, it is possible to predict with high specificity rats with susceptibility to depressive-like phenotype and resilient to the depressive-like phenotype. We also demonstrated, for the first time, that patterns of H3K4me3, H3K9me3, H3K27me3, and H3K36me3 trimethylation are strictly associated with the resilient or susceptible to depressive-like phenotype in a brain-region-specific manner. Additionally, susceptible animals have reduced DCx and GFAP and resilient animals present increase of AQP-4 immunoreactivity. Together, these results provide evidence that H3 trimethylations are related to the development of the resilient or susceptible to depressive-like phenotype, contributing to further advances in the pathophysiology of MDD and the discovery of mechanisms behind resilience.

Ornithine Aspartate and Vitamin-E Combination Has Beneficial Effects on Cardiovascular Risk Factors in an Animal Model of Nonalcoholic Fatty Liver Disease in Rats.

Cardiovascular (CV) disease is the main cause of death in nonalcoholic fatty liver disease (NAFLD), a clinical condition without any approved pharmacological therapy. Thus, we investigated the effects of ornithine aspartate (LOLA) and/or Vitamin E (VitE) on CV parameters in a steatohepatitis experimental model. Adult Sprague Dawley rats were randomly assigned (10 animals each) and treated from 16 to 28 weeks with gavage as follows: controls (standard diet plus distilled water (DW)), NAFLD (high-fat choline-deficient diet (HFCD) plus DW), NAFLD+LOLA (HFCD plus LOLA (200 mg/kg/day)), NAFLD+VitE (HFCD plus VitE (150 mg twice a week)) or NAFLD+LOLA+VitE in the same doses. Atherogenic ratios were higher in NAFLD when compared with NAFLD+LOLA+VitE and controls (p < 0.05). Serum concentration of IL-1ß, IL-6, TNF-α, MCP-1, e-selectin, ICAM-1, and PAI-1 were not different in intervention groups and controls (p > 0.05). NAFLD+LOLA decreased miR-122, miR-33a, and miR-186 (p < 0.05, for all) in relation to NAFLD. NAFLD+LOLA+VitE decreased miR-122, miR-33a and miR-186, and increased miR-126 (p < 0.05, for all) in comparison to NAFLD and NAFLD+VitE. NAFLD+LOLA and NAFLD+LOLA+VitE prevented liver collagen deposition (p = 0.006) in comparison to NAFLD. Normal cardiac fibers (size and shape) were lower in NAFLD in relation to the others; and the inverse was reported for the percentage of regular hypertrophic cardiomyocytes. NAFLD+LOLA+VitE promoted a significant improvement in atherogenic dyslipidemia, liver fibrosis, and paracrine signaling of lipid metabolism and endothelial dysfunction. This association should be further explored in the treatment of NAFLD-associated CV risk factors.

Intranasal HSP70 administration protects against dopaminergic denervation and modulates neuroinflammatory response in the 6-OHDA rat model.

HSP70 is one of the main molecular chaperones involved in the cellular stress response. Besides its chaperone action, HSP70 also modulates the immune response. Increased susceptibility to toxic insults in intra- and extracellular environments has been associated with insufficient amounts of inducible HSP70 in adult neurons. On the other hand, exogenous HSP70 administration has demonstrated neuroprotective effects in experimental models of age-related disorders. In this regard, this study investigated the effects of exogenous HSP70 in an animal model of dopaminergic denervation of the nigrostriatal axis. After unilateral intrastriatal injection with 6-hydroxydopamine (6-OHDA), the animals received purified recombinant HSP70 through intranasal administration (2 µg/rat/day) for 15 days. Our results indicate a neuroprotective effect of intranasal HSP70 against dopaminergic denervation induced by 6-OHDA. Exogenous HSP70 improved motor impairment and reduced the loss of dopaminergic neurons caused by 6-OHDA. Moreover, HSP70 modulated neuroinflammatory response in the substantia nigra, an important event in Parkinson's disease pathogenesis. Specifically, HSP70 treatment reduced microglial activation and astrogliosis induced by 6-OHDA, as well as IL-1ß mRNA expression in this region. Also, recombinant HSP70 increased the protein content of HSP70 in the substantia nigra of rats that received 6-OHDA. These data suggest the neuroprotection of HSP70 against dopaminergic neurons damage after cellular stress. Finally, our results indicate that HSP70 neuroprotective action against 6-OHDA toxicity is related to inflammatory response modulation.