Neuroprotective effects of soy isoflavones on chronic ethanol-induced dementia in male ICR mice

Neuroprotective potential of formononetin, a naturally occurring isoflavone phytoestrogen

The increased prevalence of neurological illnesses is a burgeoning challenge to the public healthcare system and presents greater financial pressure. Formononetin, an O-methylated isoflavone, has gained a lot of attention due to its neuroprotective potential explored in several investigations. Formononetin is widely found in legumes and several types of clovers including Trifolium pratense L., Astragalus membranaceus, Sophora tomentosa, etc. Formononetin modulates various endogenous mediators to confer neuroprotection. It prevents RAGE activation that results in the inhibition of neuronal damage via downregulating the level of ROS and proinflammatory cytokines. Furthermore, formononetin also increases the expression of ADAM-10, which affects the pathology of neurodegenerative disease by lowering tau phosphorylation, maintaining synaptic plasticity, and boosting hippocampus neurogenesis. Besides these, formononetin also increases the expression of antioxidants, Nrf-2, PI3K, ApoJ, and LRP1. Whereas, reduces the expression of p65-NF-κB and proinflammatory cytokines. It also inhibits the deposition of Aβ and MAO-B activity. An inhibition of Aβ/RAGE-induced activation of MAPK and NOX governs the protection elicited by formononetin against inflammatory and oxidative stress-induced neuronal damage. Besides this, PI3K/Akt and ER-α-mediated activation of ADAM10, ApoJ/LRP1-mediated clearance of Aβ, and MAO-B inhibition-mediated preservation of dopaminergic neurons integrity are the major modulations produced by formononetin. This review covers the biosynthesis of formononetin and key molecular pathways modulated by formononetin to confer neuroprotection.

Different types of milk consumption and the risk of dementia: Analysis from a large-scale cohort study

BACKGROUND & AIMS

Previous studies have investigated whether milk consumption has a role in preventing the development of cognitive impairment, but the results were inconsistent. Importantly, most of them have disregarded the role of different types of milk. This study aimed to examine the associations between different types of milk consumption and the risk of dementia.

METHODS

In this large-scale cohort study, participants without cognitive impairment at baseline were included from the UK Biobank. The type of milk mainly used was self-reported at baseline, including full-cream milk, skimmed-milk, soy milk, other milk, and no milk. The primary outcome was all-cause dementia. Secondary outcomes included Alzheimer's disease and vascular dementia.

RESULTS

Of the 307,271 participants included in the study (mean age 56.3 [SD 8.1] years), 3789 (1.2%) incident all-cause dementia cases were observed over a median follow-up of 12.3 years. After adjustment for potential confounders, only soy milk consumers had a statistically significantly lower risk of all-cause dementia compared with no milk consumers (hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.54 to 0.90). When compared with soy milk non-consumers consisting of full-cream milk, skimmed-milk, and other milk consumers, soy milk consumers still showed a lower risk of all-cause dementia (HR, 0.76; 95% CI, 0.63 to 0.92), and there was no significant interaction with genetic risk for dementia (P for interaction = 0.15). Soy milk consumers showed a lower risk of Alzheimer's disease (HR, 0.70; 95% CI, 0.51 to 0.94; P = 0.02), while the association was not significant for vascular dementia (HR, 0.72; 95% CI, 0.47 to 1.12; P = 0.14).

CONCLUSIONS

The main consumption of soy milk was associated with a lower risk of dementia, particularly non-vascular dementia. Additional studies are needed to investigate how this association varies with the dose or frequency of the consumption of soy milk and to examine the generalizability of these findings in different populations.

Roles of genistein in learning and memory during aging and neurological disorders

Genistein (GEN) is a non-steroidal phytoestrogen that belongs to the isoflavone class. It is abundantly found in soy. Soy and its products are used as food components in many countries including India. The present review is focused to address roles of GEN in brain functions in the context of learning and memory as a function of aging and neurological disorders. Memory decline is one of the most disabling features observed during normal aging and age-associated neurodegenerative disorders namely Alzheimer's disease (AD) and Parkinson's disease (PD), etc. Anatomical, physiological, biochemical and molecular changes in the brain with advancement of age and pathological conditions lead to decline of cognitive functions. GEN is chemically comparable to estradiol and binds to estrogen receptors (ERs). GEN acts through ERs and mimics estrogen action. After binding to ERs, GEN regulates a plethora of brain functions including learning and memory; however detailed study still remains elusive. Due to the neuroprotective, anti-oxidative and anti-inflammatory properties, GEN is used to restore or improve memory functions in different animal models and humans. The present review may be helpful to understand roles of GEN in learning and memory during aging and neurological disorders, its direction of research and therapeutic perspectives.

Soy isoflavones alleviate lipopolysaccharide-induced depressive-like behavior by suppressing neuroinflammation, mediating tryptophan metabolism and promoting synaptic plasticity

Depression is highly prevalent in patients suffering from chronic inflammatory diseases. Dysregulated neuroinflammation and concomitant-activated microglia play a pivotal role in the pathogenesis of depression. As one of the biologically functional phytochemicals in soybeans, soy isoflavones (SI) have been reported to exhibit anti-inflammatory, antioxidant, estrogen-like and neuroprotective activities. However, there is no research on how SI administration affects the depressive-like behavior induced by neuroinflammation. Therefore, this study was conducted to evaluate the antidepressant-like action of SI in acute lipopolysaccharide (LPS)-treated mice and to explore its underlying mechanisms. An open field test, a sucrose preference experiment, a tail suspension test and a forced swimming task were conducted to assess the influence of SI on the depressive-like behavior induced by LPS injection. Then, the levels of the pro-inflammation cytokines, tryptophan (Trp) metabolism in the cortex and hippocampus, and the synaptic plasticity-related signal pathway in the hippocampus, which are involved in the pathophysiology of depression, were examined. The results showed that SI administration remarkably alleviated LPS-induced depressive-like behavior as indicated by the increased sucrose preference index and the decreased immobility time both in the tail suspension test and the forced swimming task. SI significantly suppressed neuroinflammation in the hippocampus of LPS mice, as indicated by a decrease in the levels of interleukin (IL)-1β, IL-10, tumor necrosis factor (TNF-α) and suppression of the signal pathway of TLR4/NF-κB. Additionally, SI administration regulated tryptophan (Trp) metabolism by increasing 5-hydroxytryptamine (5-HT) levels, inhibiting the release of kynurenine (KYN) in the cortex and hippocampus, and elevating the expressions of synaptic plasticity-related protein markers such as postsynaptic density-95 (PSD-95) and synaptophysin (SYN). The current study demonstrated that soy isoflavones could reverse LPS-induced depressive-like behavior by suppressing neuroinflammation, normalizing the Trp metabolism, up-regulating the expressions of synaptic plasticity-related proteins, and inhibiting the TLR4/NF-κB pathway activation in the hippocampus of mice, exerting their antidepressant-like action.

Soy isoflavones protects against cognitive deficits induced by chronic sleep deprivation via alleviating oxidative stress and suppressing neuroinflammation

Mounting evidence suggests that there is a close association between chronic sleep deprivation (CSD) and cognitive deficits. The animal model of CSD-induced cognitive deficits is commonly used to seek potential treatments. Soy isoflavones (SI) have been reported to possess antioxidant, anti-inflammation, and neuroprotective effects. In the present study, the effects of SI on CSD-induced memory impairment were investigated. The mice were subjected to the sleep interruption apparatus and continuously sleep deprived for 2 weeks, while orally administrated with SI (10, 20, and 40 mg/kg) or Modafinil (MOD,100 mg/kg) during the CSD process. Immediately after the SD protocol, cognitive performance of mice was evaluated by the object location recognition (OLR) test, the novel object recognition (NOR) test, and the Morris water maze (MWM) task, as well as the hippocampus, was extracted for evaluation of oxidative stress parameters and inflammation levels through biochemical parameter assay and western blotting analysis. The results showed that SI administration remarkably improved the cognitive performance of CSD-treated mice in OLR, NOR, and MWM tests. In addition, SI significantly elevated total antioxidant capacity and superoxide dismutase enzyme activities, decreased malondialdehyde level, promoting antioxidant element nuclear erythroid-2-related factor 2, and its downstream targets, including heme oxygenase 1, and quinone oxidoreductase 1 protein expressions. Moreover, SI treatment significantly suppressed nuclear factor kappa B p65, nitric oxide synthase, and cyclooxygenase 2 activation, as well as the pro-inflammatory cytokines (Tumor necrosis factor-α [TNF-α], interleukin-6 [IL-6], and interleukin-1β [IL-1β]) release in the hippocampus of CSD-treated mice. In summary, the current study provides an insight into the potential of SI in treatment of cognitive deficits by CSD.

Compatibility with Semen Sojae Praeparatum attenuates hepatotoxicity of Gardeniae Fructus by regulating the microbiota, promoting butyrate production and activating antioxidant response

BACKGROUND

Herb-induced liver injury is a leading cause of drug-induced liver injury in China and its incidence is also increasing worldwide. Gardeniae Fructus (ZZ) has aroused wide concern for hepatotoxicity in recent decades. But when ZZ is administered in combination with Semen Sojae Praeparatum (DDC) to compose a herbal pair Zhizichi Decoction (ZZCD), lower hepatotoxicity is observed. The mechanism involved in the attenuated effect remains to be investigated.

HYPOTHESIS/PURPOSE

Our previous studies showed that DDC benefited host metabolism by regulating the gut microbiota and it reduced the exposure of major toxic components of ZZ. The present study was aimed to investigate how DDC attenuated hepatotoxicity of ZZ from the perspective of gut microbiota.

METHODS

Rats received ZZ and ZZCD treatment of different dosages and antibiotic treatment was applied to explore the involvement of gut microbiota. Biochemical assays and histopathological analysis were conducted to evaluate liver injury. Gut microbiota in caecal contents was profiled by 16S rRNA sequencing. Short-chain fatty acids (SCFAs) in caecal contents were measured by gas chromatography mass spectrometry (GCMS). To verify the protective effect of butyrate, it was administered with genipin, the major hepatotoxic metabolite of ZZ, to rats and HepG2 cells. Plasma lipopolysaccharide (LPS) level and colon tissue section were used to evaluate gut permeability. Expression level of Nuclear factor erythroid-derived 2-like 2 (Nrf2) was detected by immunohistochemistry in vitro and by western blot in vivo.

RESULTS

Our study showed that ZZCD displayed lower hepatotoxicity than ZZ at the same dosage. ZZ induced gut dysbiosis, significantly reducing Lactobacillus and Enterococcus levels and increasing the Parasutterella level. In combination with DDC, these alterations were reversed and beneficial genus including Akkermansia and Prevotella were significantly increased. Besides, butyrate production was diminished by ZZ but was restored when in combination with DDC. Butyrate showed detoxification on genipin-induced liver injury by promoting colon integrity and promoting Nrf2 activation. Besides, it protected genipin-induced hepatocyte damage by promoting Nrf2 activation.

CONCLUSION

DDC attenuates ZZ-induced liver injury by regulating the microbiota, promoting butyrate production and activating antioxidant response.