Propionate ameliorates diabetes-induced neurological dysfunction through regulating the PI3K/Akt/eNOS signaling pathway

The effects of ecdysterone and enalapril on nitric oxide synthesis and the markers of oxidative stress in streptozotocin-induced diabetes in rats: a comparative study

Cardiovascular functions in diabetes greatly depend on constitutive NOS (cNOS) activity. A comparative study of the effects of a steroid hormone ecdysterone and enalapril, an ACE inhibitor widely used to treat cardiac disorders on cNOS, inducible NOS (iNOS), xanthine oxidoreductase (XOR) activity, RNS, ROS, and lipid peroxidation in heart tissue in experimental diabetes was conducted. The rat model of diabetes was established by streptozotocin injection. NOS activity, NO2-, NO3-, uric acid, nitrosothiols, hydroperoxide, superoxide, and diene conjugate formation were studied spectrophotomerically. In diabetes, cNOS downregulation correlated with a dramatic fall of NO2- production and ~4.5-fold elevation of nitrosothiols, which agreed with a steep rise of iNOS activity, while NO3- remained close to control. Dramatic activation of XOR was observed, which correlated with the elevation of both superoxide production and nitrate reductase activity and resulted in strong lipid peroxidation. Ecdysterone and enalapril differently affected RNS metabolism. Ecdysterone moderately restored cNOS but strongly suppressed iNOS, which resulted in the reduction of NO3-, but full restoration of NO2- production. Enalapril better restored cNOS but less effectively suppressed iNOS, which promoted NO3- formation. Both drugs similarly inhibited XOR, which equally alleviated oxidative stress and lipid peroxidation. The synergistic action of iNOS and XOR was a plausible explanation for strong lipid peroxidation, abolished by the inhibition of iNOS and XOR by ecdysterone or enalapril. Complementary effects of ecdysterone and enalapril on cNOS, iNOS, and RNS are a promising basis for their combined use in the treatment of cardiovascular disorders caused by cNOS dysfunction in diabetes.

Propionic acid ameliorates cognitive function through immunomodulatory effects on Th17 cells in perioperative neurocognitive disorders

Background

Elderly patients undergoing surgery are prone to cognitive decline known as perioperative neurocognitive disorders (PND). Several studies have shown that the microglial activation and the decrease of short-chain fatty acids (SCFAs) in gut induced by surgery may be related to the pathogenesis of PND. The purpose of this study was to determine whether microglia and short-chain fatty acids were involved in cognitive dysfunction in aged rats.

Methods

Male wild-type Wistar rats aged 11-12 months were randomly divided into control group (Ctrl: Veh group), propionic acid group (Ctrl: PA group), exploratory laparotomy group (LP: Veh group) and propionic acid + exploratory laparotomy group (LP: PA group) according to whether exploratory laparotomy (LP) or PA pretreatment for 21 days was performed. The motor ability of the rats was evaluated by open field test on postoperative day 3 (POD3), and then the cognitive function was evaluated by Y-maze test and fear conditioning test. The expression of IL-1β, IL-6, RORγt and IL-17A mRNA in hippocampus was detected by RT-qPCR, the expression of IL-17A and IL-17RA in hippocampus was detected by Western blot, and the activation of microglia was detected by immunofluorescence.

Results

The PND rat model was successfully established by laparotomy. Compared with Ctrl: Veh group, the body weight of LP: Veh group decreased, the percentage of spontaneous alternations in Y maze decreased (P < 0.001), and the percentage of freezing time in contextual fear test decreased (P < 0.001). Surgery triggers neuroinflammation, manifested as the elevated levels of the inflammatory cytokines IL-1β (P < 0.001) and IL-6 (P < 0.001), the increased expression of the transcription factor RORγt (P = 0.0181, POD1; P = 0.0073, POD5)and major inflammatory cytokines IL-17A (P = 0.0215, POD1; P = 0.0071, POD5), and the increased average fluorescence intensity of Iba1 (P < 0.001, POD1; P < 0.001, POD5). After PA preconditioning, the recovery of rats in LP: PA group was faster than that in LP: Veh group as the body weight lost on POD1 (P = 0.0148) was close to the baseline level on POD5 (P = 0.1846), and they performed better in behavioral tests. The levels of IL-1β (P < 0.001) and IL-6 (P = 0.0035) inflammatory factors in hippocampus decreased on POD1 and the average fluorescence intensity of Iba1 decreased (P = 0.0024, POD1; P < 0.001, POD5), representing the neuroinflammation was significantly improved. Besides, the levels of RORγt mRNA (P = 0.0231, POD1; P = 0.0251, POD5) and IL-17A mRNA (P = 0.0208, POD1; P = 0.0071, POD5) in hippocampus as well as the expression of IL-17A (P = 0.0057, POD1; P < 0.001, POD5) and IL-17RA (P = 0.0388) decreased.

Conclusion

PA pretreatment results in reduced postoperative neuroinflammation and improved cognitive function, potentially attributed to the regulatory effects of PA on Th17-mediated immune responses.

Characteristics of elderly diabetes patients: focus on clinical manifestation, pathogenic mechanism, and the role of traditional Chinese medicine

Diabetes mellitus has become a major public health issue globally, putting an enormous burden on global health systems and people. Among all diseased groups, a considerable part of patients are elderly, while their clinical features, pathogenic processes, and medication regimens are different from patients of other ages. Despite the availability of multiple therapies and techniques, there are still numerous elderly diabetes patients suffering from poor blood glucose control, severe complications, and drug adverse effects, which negatively affect the quality of life in their golden years. Traditional Chinese Medicine (TCM) has been widely used in the treatment of diabetes for several decades, and its relevant clinical practice has confirmed that it has a satisfactory effect on alleviating clinical symptoms and mitigating the progression of complications. Chinese herbal medicine and its active components were used widely with obvious clinical advantages by multiple targets and signaling pathways. However, due to the particular features of elderly diabetes, few studies were conducted to explore Traditional Chinese Medicine intervention on elderly diabetic patients. This study reviews the research on clinical features, pathogenic processes, treatment principles, and TCM treatments, hoping to provide fresh perspectives on the prevention and management strategies for elderly diabetes.

Effects of short-chain fatty acids on blood glucose and lipid levels in mouse models of diabetes mellitus: A systematic review and network meta-analysis

Short-chain fatty acids (SCFAs), the main metabolites of gut microbiota, have been associated with lower blood glucose and lipid levels in diabetic mice. However, a comprehensive summary and comparison of the effects of different SCFA interventions on blood glucose and lipid levels in diabetic mice is currently unavailable. This study aims to compare and rank the effects of different types of SCFAs on blood glucose and lipid levels by collecting relevant animal research. A systematic search through PubMed, Embase, Cochrane Library, and Web of Science database was conducted to identify relevant studies from inception to March 17, 2023. Both pairwise meta-analysis and Bayesian network meta-analysis were used for statistical analyses. In total, 18 relevant studies involving 5 interventions were included after screening 3793 citations and 53 full-text articles. Notably, butyrate therapy (mean difference [MD] = -4.52, 95% confidence interval [-6.29, -2.75]), acetate therapy (MD = -3.12, 95% confidence interval [-5.79, -0.46]), and propionate therapy (MD = -2.96, 95% confidence interval [-5.66, -0.26]) significantly reduced the fasting blood glucose levels compared to the control group; butyrate therapy was probably the most effective intervention, with a surface under the cumulative ranking curve (SUCRA) value of 85.5%. Additionally, acetate plus propionate therapy was probably the most effective intervention for reducing total cholesterol (SUCRA = 85.8%) or triglyceride levels (SUCRA = 88.1%). These findings underscore the potential therapeutic implications of SCFAs for addressing metabolic disorders, particularly in type 2 diabetes mellitus.

Cognitive protection of sinomenine in type 2 diabetes mellitus through regulating the EGF/Nrf2/HO-1 signaling, the microbiota-gut-brain axis, and hippocampal neuron ferroptosis

Recent years have witnessed a growing research interest in traditional Chinese medicine as a neuroprotective nutrient in the management of diabetic cognitive dysfunction. However, the underlying molecular mechanisms of sinomenine in mediating ferroptosis of hippocampal neurons have been poorly understood. This study sought to decipher the potential effect and molecular mechanism of sinomenine in the cognitive dysfunction following type 2 diabetes mellitus (T2DM). Multi-omics analysis was conducted to identify the microbiota-gut-brain axis in T2DM patient samples obtained from the publicly available database. In HT-22 cells, erastin was utilized to create a ferroptosis model, and streptozotocin was injected intraperitoneally to create a rat model of DM. It was noted that intestinal flora imbalance occurred in patients with T2DM-associated cognitive dysfunction. Sinomenine could reduce Erastin-induced hippocampus neuronal ferroptosis by increasing EGF expression. EGF protected hippocampal neurons against ferroptosis by activating the Nrf2/HO-1 signaling pathway. Furthermore, in vivo results confirmed that sinomenine blocked ferroptosis of hippocampal neurons and alleviated cognitive dysfunction in T2DM rats. Collectively, these results suggest that sinomenine confers neuroprotective effects by curtailing hippocampal neuron ferroptosis via the EGF/Nrf2/HO-1 signaling and microbiota-gut-brain axis. It may be a candidate for the treatment of diabetic cognitive dysfunction.

Microbiota-derived short-chain fatty acids mediate the effects of dengzhan shengmai in ameliorating cerebral ischemia via the gut-brain axis

ETHNOPHARMACOLOGICAL RELEVANCE

Dengzhan shengmai (DZSM) formula, composed of four herbal medicines (Erigeron breviscapus, Panax ginseng, Schisandra chinensis, and Ophiopogon japonicus), is widely used in the recovery period of ischemic cerebrovascular diseases; however, the associated molecular mechanism remains unclear.

AIM OF THE STUDY

The purpose of this study was to uncover the links between the microbiota-gut-brain axis and the efficacy of DZSM in ameliorating cerebral ischemic diseases.

MATERIALS AND METHODS

The effects of DZSM on the gut microbiota community and bacteria-derived short-chain fatty acid (SCFA) production were evaluated in vivo using a rat model of cerebral ischemia and in vitro through the anaerobic incubation with fresh feces derived from model animals. Subsequently, the mechanism underlying the role of SCFAs in the DZSM-mediated treatment of cerebral ischemia was explored.

RESULTS

We found that DZSM treatment significantly altered the composition of the gut microbiota and markedly enhanced SCFA production. The consequent increase in SCFA levels led to the upregulation of the expression of monocarboxylate transporters and facilitated the transportation of intestinal SCFAs into the brain, thereby inhibiting the apoptosis of neurocytes via the regulation of the PI3K/AKT/caspase-3 pathway. The increased intestinal SCFA levels also contributed to the repair of the 2VO-induced disruption of gut barrier integrity and inhibited the translocation of lipopolysaccharide from the intestine to the brain, thus attenuating neuroinflammation. Consequently, cerebral neuropathy and oxidative stress were significantly improved in 2VO model rats, leading to the amelioration of cerebral ischemia-induced cognitive dysfunction. Finally, fecal microbiota transplantation could reproduce the beneficial effects of DZSM on SCFA production and cerebral ischemia.

CONCLUSIONS

Our findings suggested that SCFAs mediate the effects of DZSM in ameliorating cerebral ischemia via the gut microbiota-gut-brain axis.

Partial enzymolysis affects the digestion of tamarind seed polysaccharides in vitro: Degradation accelerates and gut microbiota regulates

Two hydrolyzed fractions of tamarind seed polysaccharide (TSP), denoted ETSP1 (176.68 kDa) and ETSP2 (34.34 kDa), were prepared by partial degradation via endo-xyloglucanase, and then characterized and evaluated by simulated gastrointestinal digestion in vitro. The results showed that the hydrolyzed TSPs remained indigestible in gastric and small intestinal media, and were fermented by gut microbiota, similar to the native TSP (M_w = 481.52 kDa). Although the degradation of hydrolyzed TSPs was accelerated during fermentation with a decreasing degree of polymerization, the content of produced total short-chain fatty acids (SCFAs) decreased. After fermentation, the gut microbiota composition was modified, esp. the Firmicutes/Bacteroidetes ratio decreased (1.06 vs. 0.96 vs. 0.80) with a decreasing degree of polymerization, which implied that the potential anti-obesity prebiotic effect was enhanced. At the genus level, hydrolyzed TSPs maintained similar roles as native TSP, including promoting beneficial bacteria (Bifidobacterium, Parabacteroides, and Faecalibacterium) and inhibiting enteropathogenic bacteria (Escherichia-Shigella and Dorea). Moreover, ETSP1 had additional potential due to abundant Bacteroides vulgatus (LDA = 4.68), and ETSP2 might perform better as related to Bacteroides xylanisolvens (LDA = 4.40). All these results indicated the prebiotic potential of hydrolyzed TSP with detailed information about changes in degradation and gut microbiota based on enzyme-hydrolysis.