Role of allopregnanolone-mediated γ-aminobutyric acid A receptor sensitivity in the pathogenesis of premenstrual dysphoric disorder: Toward precise targets for translational medicine and drug development.

Premenstrual dysphoric disorder (PMDD) can be conceptualized as a disorder of suboptimal sensitivity to neuroactive steroid hormones. Its core symptoms (emotional instability, irritability, depression, and anxiety) are related to the increase of stress sensitivity due to the fluctuation of hormone level in luteal phase of the menstrual cycle. In this review, we describe the emotional regulatory effect of allopregnanolone (ALLO), and summarize the relationship between ALLO and γ-aminobutyric acid A (GABAA) receptor subunits based on rodent experiments and clinical observations. A rapid decrease in ALLO reduces the sensitivity of GABAA receptor, and reduces the chloride influx, hindered the inhibitory effect of GABAergic neurons on pyramidal neurons, and then increased the excitability of pyramidal neurons, resulting in PMDD-like behavior. Finally, we discuss in depth the treatment of PMDD with targeted GABAA receptors, hoping to find a precise target for drug development and subsequent clinical application. In conclusion, PMDD pathophysiology is rooted in GABAA receptor sensitivity changes caused by rapid changes in ALLO levels. Targeting GABAA receptors may alleviate the occurrence of PMDD.

Glyphosate-induced autophagy inhibition results in hepatic steatosis via mediating epigenetic reprogramming of PPARα in roosters.

Glyphosate (Gly) is the most widely used herbicide with well-defined hepatotoxic effects, but the underlying mechanisms of Gly-induced hepatic steatosis remain largely unknown. In this study, a rooster model combined with primary chicken embryo hepatocytes was established to dissect the progresses and mechanisms of Gly-induced hepatic steatosis. Data showed that Gly exposure caused liver injury with disrupted lipid metabolism in roosters, manifested by significant serum lipid profile disorder and hepatic lipid accumulation. Transcriptomic analysis revealed that PPARα and autophagy-related pathways played important roles in Gly-induced hepatic lipid metabolism disorders. Further experimental results suggested that autophagy inhibition was involved in Gly-induced hepatic lipid accumulation, which was confirmed by the effect of classic autophagy inducer rapamycin (Rapa). Moreover, data substantiated that Gly-mediated autophagy inhibition caused nuclear increase of HDAC3, which altered epigenetic modification of PPARα, leading to fatty acid oxidation (FAO) inhibition and subsequently lipid accumulation in the hepatocytes. In summary, this study provides novel evidence that Gly-induced autophagy inhibition evokes the inactivation of PPARα-mediated FAO and concomitant hepatic steatosis in roosters by mediating epigenetic reprogramming of PPARα.

Inhibited transcription factor EB function induces reactive oxygen species overproduction to promote pyroptosis in cadmium-exposed renal tubular epithelial cells.

Pyroptosis is a pro-inflammatory type of cell death involved in the pathogenesis of multiple kidney diseases, while transcription factor EB (TFEB) is shown to be important for rescuing renal function. Cadmium (Cd) is an omnipresent toxic heavy metal with definite nephrotoxicity, but there is lacking of evidence regarding an interplay between TFEB activity and pyroptosis during Cd exposure. In this study, Cd-exposed NRK-52E cells were used to clarify this issue as an in vitro model of acute kidney injury. First, our results showed that Cd exposure evidently elevated the protein levels involved in pyroptosis, increased lactate dehydrogenase (LDH) release, and disrupted the cell membrane integrity, suggesting the occurrence of pyroptosis in NRK-52E cells. It is also shown that Cd induced a burst of reactive oxygen species (ROS) to mediate pyroptosis. Simultaneously, downregulated TFEB expression with its inhibited nuclear translocation was revealed in Cd-exposed NRK-52E cells. Further investigations have demonstrated that TFEB knockdown promoted Cd-induced ROS production to exacerbate the pyroptosis, while TFEB overexpression inhibited Cd-induced ROS production to alleviate the pyroptosis in NRK-52E cells. In summary, these findings demonstrate that Cd-inhibited TFEB function results in ROS overproduction to promote pyroptosis in NRK-52E cells, which provide new insight into the therapeutic targets for Cd-induced kidney diseases.

Glyphosate-induced gut microbiota dysbiosis facilitates male reproductive toxicity in rats.

Glyphosate (GLY), a ubiquitous environmental pollutant, can result in gut microbiota dysbiosis intimately involving various diseases. The latest research has shown an association between gut microbiota alteration and defective spermatogenesis. Here, we aimed to investigate whether GLY-induced gut microbiota dysbiosis contributed to male reproductive toxicity. Data showed that GLY-exposed rats exhibited male reproductive dysfunction, evidenced by impaired testis architectural structure, reduced sperm motility, together with increased sperm malformation ratio. 16S rDNA sequencing analysis indicated that GLY exposure altered the composition of gut commensal microbiota, of which the relative abundance of Bacteroidetes and Firmicutes phyla was significantly changed. Unexpectedly, the increased abundance of Prevotella_1 and Bacteroides genera was negatively correlated with sperm quality. Mechanistically, the pathological changes in GLY-exposed testis were accompanied by the increased interleukin (IL)-17A production, probably due to gut microbes-derived Th17 cell migration. Furthermore, activation of IL-17A signaling triggered testicular oxidative damage. Taken together, these findings uncover an underlying mechanistic scenario that gut microbiota dysbiosis-driven local IL-17A production is one reason responsible for male reproductive toxicity induced by GLY, which provides new insights into the male reproductive toxicity of GLY in mammals.

Glyphosate damages blood-testis barrier via NOX1-triggered oxidative stress in rats: Long-term exposure as a potential risk for male reproductive health.

Blood-testis barrier (BTB) creates a privileged niche indispensable for spermatogenesis. Glyphosate (GLY), the most commonly used herbicide worldwide, has been reported to decrease sperm quality. However, whether and how GLY destroys the BTB to affect sperm quality remains to be elucidated. Herein, this study was designed to investigate the influence of GLY on the BTB in vivo and in vitro experiments. The results showed that male rats exposed to GLY for 4 months exhibited a decrease in sperm quality and quantity, accompanied by BTB integrity disruption and testicular oxidative stress. Additionally, GLY-induced reactive oxygen species (ROS) contributed to the downregulation of BTB-related proteins in primary Sertoli cells (SCs). Intriguingly, we identified a marked upregulation of oxidative stress-related gene NOX1 in GLY-exposed testis based on transcriptome analysis. NOX1 knockdown blocked the GLY-induced oxidative stress, as well as prevented BTB-related protein decrease in SCs. Furthermore, the estrogen receptor (ER)-α was significantly upregulated in vivo and in vitro models. An ER-α inhibitor decreased the expression levels of both ER-α and NOX1. Mechanistically, GLY directly interacted with ER-α at the site of Pro39 and Lys401 to promote ER-α activation, which boosted NOX1 expression to trigger ROS accumulation. Collectively, these results demonstrate that long-term GLY exposure adversely affects BTB integrity, which disrupts spermatogenesis via activation of ER-α/NOX1 axis. This study presents a better understanding of the risk of long-term GLY exposure to male fertility.

Quercetin alleviates Cadmium-induced autophagy inhibition via TFEB-dependent lysosomal restoration in primary proximal tubular cells.

Autophagy dysregulation plays a pivotal role in cadmium (Cd)-induced nephrotoxicity. Quercetin (Qu), a flavonoid antioxidant with autophagy-enhancing effect, has protective effect on Cd-induced toxicity, but whether it can prevent Cd-induced nephrotoxicity via restoration of autophagy remains unknown. Here, primary rat proximal tubular (rPT) cells were exposed to Cd and/or Qu in vitro to clarify this issue. Data first showed that Cd-impaired autophagic flux was markedly alleviated by Qu, including decreased levels of autophagy marker proteins and recovery of autophagosome-lysosome fusion targeted for lysosomes. Meanwhile, Cd-induced lysosomal alkalization due to v-ATPases inhibition was prominently recovered by Qu. Accordingly, Qu enhanced Cd-diminished lysosomal degradation capacity and lysosome-related gene transcription levels. Notably, Qu improved Cd-inhibited TFEB nuclear translocation and its gene transcription level. Furthermore, data showed that the restoration of Cd-impaired autophagy-lysosome pathway and resultant alleviation of cytotoxicity by Qu are TFEB-dependent using TFEB gene silencing and overexpression technologies. In summary, these data provide novel evidences that the protective action of Qu against Cd-induced autophagy inhibition is attributed to its restoration of lysosomal dysfunction, which is dependent on TFEB.

Involvement of Nrf2 and mitochondrial apoptotic signaling in trehalose protection against cadmium-induced kidney injury.

Cadmium (Cd) poisoning is characterized by multiple organ dysfunction in organisms, and the kidney is the main target organ of Cd toxicity. Trehalose (Tr), a multifunctional bioactive disaccharide, possesses potential kidney protective properties. Nevertheless, the specific biological function of Tr in antagonizing kidney injury induced by Cd remains to be elucidated. Herein, an in vivo model of Tr antagonizing Cd nephrotoxicity was established and the indictors related to kidney function, oxidative stress, and apoptosis were detected to investigate the molecular mechanism underlying the Tr-protection against Cd-induced kidney injury of rats. Firstly, Tr significantly declined the levels of blood urea nitrogen (BUN) and serum creatinine, and partially restored renal pathological changes caused by Cd. Secondly, Cd exposure significantly increased the malondialdehyde (MDA) content, and decreased the levels of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione (GSH) in serum. However, Tr significantly ameliorated these abnormal alterations. Moreover, Tr regulated the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway to suppress the Cd-induced nuclear translocation of Nrf2 and the up-regulation of heme oxygenase-1 (HO-1) and NAD (P) H quinone reductase-1 (NQO1). Meanwhile, Tr significantly reversed the increased Sequestosome-1(SQSTM1/p62) and decreased Kelch-like ECH associated protein-1 (Keap1) protein levels induced by Cd. Thirdly, further mechanistic exploration suggested that Tr inhibited the mitochondrial apoptotic signaling pathway induced by Cd. Collectively, the results indicated that Tr exerts antioxidant and anti-apoptosis functions involving the Nrf2 and mitochondrial apoptotic signaling pathways to protect against Cd-induced kidney injury in rats.

High fat diet-triggered non-alcoholic fatty liver disease: A review of proposed mechanisms.

Obesity is characterized by the deposition of excessive body fat, and is caused by energy imbalance, especially when consuming fat-rich diets. High fat diet (HFD)-associated obesity is greatly common in patients with non-alcoholic fatty liver disease (NAFLD) that is emerging as one of the most universal causes of liver disease worldwide, especially in Western countries. In spite of its high prevalence, only a small proportion of affected individuals will become inflamed, followed by fibrosis and chronic liver diseases, and most patients only show simple steatosis. In this case, the full comprehension of the mechanisms underlying the progression of NAFLD is of extreme significance; in spite of progress in this field, awareness on the development of NAFLD is still incomplete. Traditionally, liver steatosis is commonly connected with HFD, obesity, and insulin resistance (IR). Recently, various possible mechanisms have been put forward for liver damage, including endoplasmic reticulum stress, perturbation of autophagy, mitochondrial dysfunction, hepatocellular apoptosis, gut microbiota imbalance, dysregulation of microRNAs, and genetic/epigenetic risk factors, as well as an increase in inflammatory responses, among many others. Collectively, these proposed mechanisms allow for a variety of hits acting together on subjects to mediated NAFLD and will offer a more accurate explanation for progression of NAFLD. Therefore, this review summarizes the present information concerning NAFLD after HFD exposure, as well as discusses possible mechanisms through which it may arise.

mTORC1 activation contributes to autophagy inhibition via its recruitment to lysosomes and consequent lysosomal dysfunction in cadmium-exposed rat proximal tubular cells.

Autophagy dysregulation is implicated in cadmium (Cd)-induced nephrotoxicity. The mammalian target of rapamycin complex 1 (mTORC1) is a negative regulator of autophagy, but its role in Cd-induced autophagy inhibition and possible regulatory mechanisms remains poorly understood. In the present study, Cd exposure activated mTORC1 in primary rat proximal tubular (rPT) cells, and two mTORC1 inhibitors (rapamycin and torin 1) were separately utilized to inhibit Cd-induced mTORC1 activation. Data showed that Cd-inhibited autophagic flux was markedly restored by two mTORC1 inhibitors, respectively, as evidenced by immunoblot analysis of autophagy marker proteins and tandem red fluorescent protein-green fluorescent protein-microtubule associated protein light chain 3 (RFP-GFP-LC3) fluorescence microscopy assay. Importantly, Cd exposure triggered the recruitment of mTORC1 onto lysosome membrane assessed by immunofluorescence co-localization analysis, which was obviously inhibited by rapamycin or torin 1. Moreover, Cd-induced lysosomal alkalization, suppressed vacuolar ATPases (V-ATPases) protein levels and impaired lysosomal degradation capacity were markedly reversed by rapamycin or torin 1. In summary, these findings demonstrate that Cd recruits mTORC1 to lysosome membrane to induce its activation, which results in lysosomal dysfunction and resultant autophagy inhibition in rPT cells.

Role of subcellular calcium redistribution in regulating apoptosis and autophagy in cadmium-exposed primary rat proximal tubular cells.

Ca2+ signaling plays a vital role in regulating apoptosis and autophagy. We previously proved that cytosolic Ca2+ overload is involved in cadmium (Cd)-induced apoptosis in rat proximal tubular (rPT) cells, but the source of elevated cytosolic Ca2+ concentration ([Ca2+]c) and the effect of potential subcellular Ca2+ redistribution on apoptosis and autophagy remain to be elucidated. Firstly, data showed that Cd-induced elevation of [Ca2+]c was primarily generated intracellularly. Moreover, elevations of [Ca2+]c and mitochondrial Ca2+ concentration ([Ca2+]mit) with depletion of endoplasmic reticulum (ER) Ca2+ levels ([Ca2+]ER) were revealed in Cd-treated rPT cells, but this subcellular Ca2+ redistribution was significantly suppressed by 2-Aminoethoxydiphenyl borate (2-APB). Elevated inositol 1,4,5-trisphosphate (IP3) levels with up-regulated IP3 receptor (IP3R) protein levels were shown in Cd-exposed cells, confirming that IP3R-mediated ER Ca2+ release results in the elevation of [Ca2+]c. Up-regulated sequestosome 1 (p62) protein levels and autophagic flux assay demonstrated that Cd impaired autophagic degradation, while N-acetylcysteine (NAC) markedly attenuated Cd-induced p62 and microtubule-associated protein 1 light chain 3-II (LC3-II) accumulation, implying that the inhibition of autophagic flux was due to oxidative stress. Furthermore, pharmacological modulation of [Ca2+]c with 1,2-Bis (2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) and 2-APB alleviated Cd-mediated apoptosis, inhibition of autophagic degradation and subsequent cytotoxicity, while thapsigargin (TG) had the opposite regulatory effect on them. In summary, cytosolic calcium overload originated from IP3R-mediated ER Ca2+ release has a negative impact on Cd nephrotoxicity through its promotion of apoptosis and inhibition of autophagic flux.

Resident intruder paradigm-induced aggression relieves depressive-like behaviors in male rats subjected to chronic mild stress.

BACKGROUND: Accumulating epidemiological evidence shows that life event stressors are major vulnerability factors for psychiatric diseases such as major depression. It is also well known that the resident intruder paradigm (RIP) results in aggressive behavior in male rats. However, it is not known how resident intruder paradigm-induced aggression affects depressive-like behavior in isolated male rats subjected to chronic mild stress (CMS), which is an animal model of depression. MATERIAL AND METHODS: Male Wistar rats were divided into 3 groups: non-stressed controls, isolated rats subjected to the CMS protocol, and resident intruder paradigm-exposed rats subjected to the CMS protocol. RESULTS: In the sucrose intake test, ingestion of a 1% sucrose solution by rats in the CMS group was significantly lower than in control and CMS+RIP rats after 3 weeks of stress. In the open-field test, CMS rats had significantly lower open-field scores compared to control rats. Furthermore, the total scores given the CMS group were significantly lower than in the CMS+RIP rats. In the forced swimming test (FST), the immobility times of CMS rats were significantly longer than those of the control or CMS+RIP rats. However, no differences were observed between controls and CMS+RIP rats. CONCLUSIONS: Our data show that aggressive behavior evoked by the resident intruder paradigm could relieve broad-spectrum depressive-like behaviors in isolated adult male rats subjected to CMS.