Catalpol ameliorates diabetes-induced testicular injury and modulates gut microbiota

Gut microbiota is involved in male reproductive function: a review

Globally, ~8%-12% of couples confront infertility issues, male-related issues being accountable for 50%. This review focuses on the influence of gut microbiota and their metabolites on the male reproductive system from five perspectives: sperm quality, testicular structure, sex hormones, sexual behavior, and probiotic supplementation. To improve sperm quality, gut microbiota can secrete metabolites by themselves or regulate host metabolites. Endotoxemia is a key factor in testicular structure damage that causes orchitis and disrupts the blood-testis barrier (BTB). In addition, the gut microbiota can regulate sex hormone levels by participating in the synthesis of sex hormone-related enzymes directly and participating in the enterohepatic circulation of sex hormones, and affect the hypothalamic-pituitary-testis (HPT) axis. They can also activate areas of the brain that control sexual arousal and behavior through metabolites. Probiotic supplementation can improve male reproductive function. Therefore, the gut microbiota may affect male reproductive function and behavior; however, further research is needed to better understand the mechanisms underlying microbiota-mediated male infertility.

Obesity and male fertility disorders

Often associated with obesity, male infertility represents a widespread condition that challenges the wellbeing of the couple. In this article, we provide a comprehensive and critical analysis of studies exploring the association between obesity and male reproductive function, to evaluate the frequency of this association, and establish the effects of increased body weight on conventional and biofunctional sperm parameters and infertility. In an attempt to find possible molecular markers of infertility in obese male patients, the numerous mechanisms responsible for infertility in overweight/obese patients are reviewed in depth. These include obesity-related functional hypogonadism, insulin resistance, hyperinsulinemia, chronic inflammation, adipokines, irisin, gut hormones, gut microbiome, and sperm transcriptome. According to meta-analytic evidence, excessive body weight negatively influences male reproductive health. This can occurr through a broad array of molecular mechanisms. Some of these are not yet fully understood and need to be further elucidated in the future. A better understanding of the effects of metabolic disorders on spermatogenesis and sperm fertilizing capacity is very useful for identifying new diagnostic markers and designing therapeutic strategies for better clinical management of male infertility.

Ubiquitinome Analysis Uncovers Alterations in Synaptic Proteins and Glucose Metabolism Enzymes in the Hippocampi of Adolescent Mice Following Cold Exposure

Cold exposure exerts negative effects on hippocampal nerve development in adolescent mice, but the underlying mechanisms are not fully understood. Given that ubiquitination is essential for neurodevelopmental processes, we attempted to investigate the effects of cold exposure on the hippocampus from the perspective of ubiquitination. By conducting a ubiquitinome analysis, we found that cold exposure caused changes in the ubiquitination levels of a variety of synaptic-associated proteins. We validated changes in postsynaptic density-95 (PSD-95) ubiquitination levels by immunoprecipitation, revealing reductions in both the K48 and K63 polyubiquitination levels of PSD-95. Golgi staining further demonstrated that cold exposure decreased the dendritic-spine density in the CA1 and CA3 regions of the hippocampus. Additionally, bioinformatics analysis revealed that differentially ubiquitinated proteins were enriched in the glycolytic, hypoxia-inducible factor-1 (HIF-1), and 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathways. Protein expression analysis confirmed that cold exposure activated the mammalian target of rapamycin (mTOR)/HIF-1α pathway. We also observed suppression of pyruvate kinase M2 (PKM2) protein levels and the pyruvate kinase (PK) activity induced by cold exposure. Regarding oxidative phosphorylation, a dramatic decrease in mitochondrial respiratory-complex I activity was observed, along with reduced gene expression of the key subunits NADH: ubiquinone oxidoreductase core subunit V1 (Ndufv1) and Ndufv2. In summary, cold exposure negatively affects hippocampal neurodevelopment and causes abnormalities in energy homeostasis within the hippocampus.

Gut microbiota-gonadal axis: the impact of gut microbiota on reproductive functions

The influence of gut microbiota on physiological processes is rapidly gaining attention globally. Despite being under-studied, there are available data demonstrating a gut microbiota-gonadal cross-talk, and the importance of this axis in reproduction. This study reviews the impacts of gut microbiota on reproduction. In addition, the possible mechanisms by which gut microbiota modulates male and female reproduction are presented. Databases, including Embase, Google scholar, Pubmed/Medline, Scopus, and Web of Science, were explored using relevant key words. Findings showed that gut microbiota promotes gonadal functions by modulating the circulating levels of steroid sex hormones, insulin sensitivity, immune system, and gonadal microbiota. Gut microbiota also alters ROS generation and the activation of cytokine accumulation. In conclusion, available data demonstrate the existence of a gut microbiota-gonadal axis, and role of this axis on gonadal functions. However, majority of the data were compelling evidences from animal studies with a great dearth of human data. Therefore, human studies validating the reports of experimental studies using animal models are important.

Dapagliflozin ameliorates diabetes-induced spermatogenic dysfunction by modulating the adenosine metabolism along the gut microbiota-testis axis

Male infertility is one of the most common complications of diabetes mellitus (DM). Dapagliflozin is widely used to manage the type II DM. This study aimed to assess the dapagliflozin's effects on the spermatogenesis by administering either dapagliflozin (Dapa) or vehicle (db) to male db/db mice, and using littermate male db/m mice as the control (Con). We further performed the integrative analyses of the cecal shotgun metagenomics, cecal/plasmatic/testicular metabolomics, and testicular proteomics. We found that dapagliflozin treatment significantly alleviated the diabetes-induced spermatogenic dysfunction by improving sperm quality, including the sperm concentration and sperm motility. The overall microbial composition was reshaped in Dapa mice and 13 species (such as Lachnospiraceae bacterium 3-1) were regarded as potential beneficial bacteria. Metabolites exhibited modified profiles, in which adenosine, cAMP, and 2'-deoxyinosine being notably altered in the cecum, plasma, and testis, respectively. Testicular protein expression patterns were similar between the Dapa and Con mice. In vivo results indicated that when compared with db group, dapagliflozin treatment alleviated apoptosis and oxidative stress in testis tissues by down-regulating 2'-deoxyinosine. This was further validated by in vitro experiments using GC-2 cells. Our findings support the potential use of dapagliflozin to prevent the diabetes-induced impaired sperm quality and to treat diabetic male infertility.

Gut-Gonad Perturbations in Type-1 Diabetes Mellitus: Role of Dysbiosis, Oxidative Stress, Inflammation and Energy-Dysbalance

Type 1 diabetes mellitus is a major metabolic disorder that affects people of all age groups throughout the world. It is responsible for the alterations in male gonadal physiology in experimental models as well as in clinical cases. On the other side, diabetes mellitus has also been associated with perturbations in the gut physiology and microbiota dysbiosis. The accumulating evidence suggests a link between the gut and gonad as evident from the i) experimental data providing insights into type 1 diabetes mellitus induced gut perturbations, ii) link of gut physiology with alterations of testicular health, iii) role of gut microbiota in androgen metabolism in the intestine, and iv) epidemiological evidence linking type 1 diabetes mellitus with inflammatory bowel disease and male infertility. Considering all the pieces of evidence, it is summarized that gut dysbiosis, oxidative stress, inflammation and energy dys-balance are the prime factors involved in the gonadal damage under type 1 diabetes mellitus, in which the gut contributes significantly. Identification of novel biomarkers and intervention of suitable agents targeting these prime factors may be a step forward to restore the gonadal damage in diabetic conditions.

Pharmacological Activity of Flavonoid Quercetin and Its Therapeutic Potential in Testicular Injury

Quercetin is a natural flavonoid widely found in natural fruits and vegetables. Recent studies have shown that quercetin mediates multiple beneficial effects in a variety of organ damage and diseases, and is considered a healthcare supplement with health-promoting potential. Male infertility is a major health concern, and testicular damage from multiple causes is an important etiology. Previous studies have shown that quercetin has a protective effect on reproductive function. This may be related to the antioxidant, anti-inflammatory, and anti-apoptotic biological activities of quercetin. Therefore, this paper reviews the mechanisms by which quercetin exerts its pharmacological activity and its role in testicular damage induced by various etiologies. In addition, this paper compiles the application of quercetin in clinical trials, demonstrating its practical effects in regulating blood pressure and inhibiting cellular senescence in human patients. However, more in-depth experimental studies and clinical trials are needed to confirm the true value of quercetin for the prevention and protection against testicular injury.

The linkage of gut microbiota and the property theory of traditional Chinese medicine (TCM): Cold-natured and sweet-flavored TCMs as an example

ETHNOPHARMACOLOGICAL RELEVANCE

The property theory of traditional Chinese medicine (TCM) is a unique medical theory based on an extensive clinical practice for thousands of years, which guides TCM doctors choosing proper medicines to treat specific diseases. The nature and flavor of TCM are a high generalization of drug's characteristics according to the property theory. Despite intensive investigations, the modern interpretation of TCM property theory still confronts several challenges, which greatly hampers the elucidation of TCM's mechanisms as well as its application. Compelling evidence has proved that gut microbiota may be a potential indicator for TCM's efficacy and mechanism. Nevertheless, at present, the relationship between the gut microbiota and the nature and flavor of TCM has not been fully elucidated.

AIM OF THE STUDY

To fill the gap in this field, we developed a comprehensive study to investigate the relationship between gut microbial community and TCM's property.

MATERIALS AND METHODS

We searched "PubMed" and "China National Knowledge Infrastructure (CNKI)" with the key word "gut microbiota", and screened the published articles related to TCM. In this review, we mainly applied cold-natured and sweet-flavored TCMs as an example to explore the modulation of cold-natured and sweet-flavored TCMs on gut microbiota, and identify the potential relationship between the alterations of gut microbiota and TCM's efficacy.

RESULTS

We found cold-natured and sweet-flavored TCMs possess several pharmacological activities and generally enrich beneficial bacteria like Akkermansia, Bacteroides, Lactobacillus and Bifidobacterium, which is in good accordance with their pharmacological effects. Simultaneously, these TCMs reduce the relative abundance of some harmful bacteria belonging to Firmicutes (Streptpcoccus, Enterococcus, Turicibacter, Anaerostipes and Oscillibacter) and Proteobacteria (Helicobacter, Enterobacter, Sutterella, Klebsiella, Desulfovibrio, Escherichia coli and Campylobacter jejuni). These results indicate that there are some intrinsic correlations between gut microbiota and the property of TCM, and gut microbiota may serve as a potential indicator to reflect the property of TCM.

CONCLUSIONS

This pilot but comprehensive review provides an interesting proposal that the ancient theory of TCM property may be interpreted by the modern biological findings in gut microbiome.

Aucubin supplementation alleviate diabetes induced-disruption of blood-testis barrier and testicular damage via stabilizing cell junction integrity

Disruption of blood-testis barrier (BTB) was a crucial pathological feature of diabetes induced-testicular injury at early phase. Aucubin (AU), a main active component in Eucommiae Cortex, has drawn attention for its benefits against male reproductive system disease. The current study was aimed at investigating the protective role of AU and exploring the underlying mechanism in diabetic model. A murine model of type 2 diabetes mellitus (T2DM) was induced by high-fat diet (HFD) combined with streptozocin (STZ). Testicular weight index and morphology, sperm quality, integrity of BTB and protein levels were analyzed. The underlying mechanism of the protective effect of AU was further explored in Sertoli cells (SCs) cultured with high glucose (HG). Our results showed AU inhibited testicular structural destruction, restored disruption of BTB and improved abnormal spermatogenic function in diabetic mice. Consistent with in vivo results, HG induced decreased transcellular resistance and increased permeability in SCs monolayers, while AU exposure reverses this trend. Meanwhile, reduced expression of Zonula occludin-1(ZO-1) and Connexin43(Cx43) in testicular tissue diabetic mice and HG-induced SCs was prominently reversed via AU treatment. Mechanistic studies suggested a high affinity interaction between AU and c-Src protein was identified based on molecular docking, and the activation of c-Src was significantly inhibited in AU treatment. Furthermore, AU significantly increased the expression of Cx43 and ZO-1 proteins HG-induced SCs, which can be further enhanced in gene-silenced c-Src cells to some extent. Our results suggested that AU ameliorated disruption of BTB and spermatogenesis dysfunction in diabetic mice via inactivating c-Src to stabilize cell junction integrity.

A Retrospective Narrative Mini-Review Regarding the Seminal Microbiota in Infertile Male

Background: Infertility is a global burden that affects both sexes with the male component remaining as an explored yet crucial research field that might offer novel evidence. Material and Methods: The present narrative mini-review aims to summarize all existing literature regarding the composition of the seminal microflora in infertile men. We performed searches in PubMed/Medline, ISI Web of Knowledge, Scopus, and ScienceDirect between 2018 and 2022 using a combination of keywords. Results: A total of n = 33 studies met the eligibility criteria and were further considered. From this, n = 14 were conducted on human patients, n = 3 on zebrafish (Danio rerio), n = 5 on rats, and n = 11 on mice. In twenty-five out of thirty-three papers, the authors sequenced the 16S rRNA; situations occurred where researchers focused on standard laboratory protocols. Lactobacillus and Bifidobacterium are widely recognized as putative beneficial lactic bacteria. These two entities are capable of restoring the host’s eubiosis to some extent, blocking pathogens’ proliferation and endotoxins, and even alleviating specific patterns encountered in disease(s) (e.g., obesity, type 1 diabetes) due to prolonged exposure to toxicants in adults or from a developmental stage. Over the years, distinct approaches have been perfected, such as the transfer of feces between two species or conventional rudimentary products with proven efficiency. Conclusions: The seminal microflora is decisive and able to modulate psychological and physiological responses. Each individual possesses a personalized microbial profile further shaped by exogenous factors, regardless of sex and species.

Preclinical Studies of Natural Products Targeting the Gut Microbiota: Beneficial Effects on Diabetes

Diabetes mellitus (DM) is a serious metabolic disease characterized by persistent hyperglycemia, with a continuously increasing morbidity and mortality. Although traditional treatments including insulin and oral hypoglycemic drugs maintain blood glucose levels within the normal range to a certain extent, there is an urgent need to develop new drugs that can effectively improve glucose metabolism and diabetes-related complications. Notably, accumulated evidence implicates that the gut microbiota is unbalanced in DM individuals and is involved in the physiological and pathological processes of this metabolic disease. In this review, we introduce the molecular mechanisms by which the gut microbiota contributes to the development of DM. Furthermore, we summarize the preclinical studies of bioactive natural products that exert antidiabetic effects by modulating the gut microbiota, aiming to expand the novel therapeutic strategies for DM prevention and management.

The Herb Pair Radix Rehmanniae and Cornus Officinalis Attenuated Testicular Damage in Mice With Diabetes Mellitus Through Butyric Acid/Glucagon-Like Peptide-1/Glucagon-Like Peptide-1 Receptor Pathway Mediated by Gut Microbiota

Growing body of research indicates that Traditional Chinese Medicine (TCM) interact with gut microbiota (GM) after oral administration. Radix Rehmanniae and Cornus Officinalis (RR-CO), a well-known TCM pair, is often used to treat diabetes mellitus (DM) and its complications. The current study aimed to explore the protective effects of RR-CO on DM induced testicular damage by modulating GM. The RR-CO treatments significantly reduced hyperglycemia, ameliorated testicular ultrastructural damage and inflammation in DM model to varying degrees. Additionally, 16S-ribosomal DNA (rDNA) sequencing results showed that RR-CO treatment increased the amount of butyric acid-producing GM, such as Clostridiaceae_1 family, and decreased the abundance of Catabacter, Marvinbryantia, and Helicobacter genera. RR-CO fecal bacteria transplantation (RC-FMT) increased the abundance of Clostridiaceae_1 in the Model FMT (M-FMT) group and ameliorated testicular damage. Furthermore, treatment with RR-CO increased the fecal butyric acid level, serum Glucagon-like peptide-1 (GLP-1) level, and testicular GLP-1 receptor (GLP-1R) expression compared to those in DM mice. Finally, intraperitoneal administration of sodium butyrate (SB) significantly improved the pathological damage to the testis and reduced inflammation in the DM group. These data demonstrated a protective effect of RR-CO on DM-induced testicular damage by modulation of GM, which may be mediated by the butyric acid/GLP/GLP-1R pathway.

Gut Microbiota: An Important Player in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is one of the common metabolic diseases in the world. Due to the rise in morbidity and mortality, it has become a global health problem. To date, T2DM still cannot be cured, and its intervention measures mainly focus on glucose control as well as the prevention and treatment of related complications. Interestingly, the gut microbiota plays an important role in the development of metabolic diseases, especially T2DM. In this review, we introduce the characteristics of the gut microbiota in T2DM population, T2DM animal models, and diabetic complications. In addition, we describe the molecular mechanisms linking host and the gut microbiota in T2DM, including the host molecules that induce gut microbiota dysbiosis, immune and inflammatory responses, and gut microbial metabolites involved in pathogenesis. These findings suggest that we can treat T2DM and its complications by remodeling the gut microbiota through interventions such as drugs, probiotics, prebiotics, fecal microbiota transplantation (FMT) and diets.

Exploring the role of gut microbiome in male reproduction

BACKGROUND

The impact of the gut microbiome on the organism has become a growing research focus with the development of 16S rRNA sequencing. However, the effect of the gut microbiome in male reproduction has yet to be investigated.

OBJECTIVE

To overview on possible mechanisms by which gut microbiome could affect male reproduction and therapeutic opportunities related to the gut microbiome METHODS: Authors searched PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library for medical subject headings terms and free text words referred to "male infertility" "testis" "gut microbiome" "insulin resistance" "erectile dysfunction" "therapy" "sex hormones" "Genital Diseases." until Dec 2nd 2021.

RESULTS

Evidence suggests that immune system activation caused by the gut microbiome translocation not only leads to testicular and epididymal inflammation but can also induce insulin resistance together with gastrointestinal hormones such as leptin and ghrelin, which in turn affects the secretion of various sex hormones such as LH, FSH, and T to regulate spermatogenesis. In addition, the gut microbiome can influence spermatogenesis by controlling and metabolizing androgens as well as affecting the blood-testis barrier. It also promotes vascular inflammation by raising trimethylamine-N-oxide (TMAO) levels in the blood, which causes erectile dysfunction. Testicular microbiome and gut microbiome can interact to influence male reproductive function. This study discusses therapeutic options such as probiotics, prebiotics, and fecal microbiota transplantation, as well as the challenges and opportunities behind ongoing research, and emphasizes the need for additional research in the future to demonstrate the links and underlying mechanisms between gut microbiome and male reproduction. Therapeutic options such as probiotic, prebiotics and fecal microbiota transplantation are potential treatments for male infertility.

DISCUSSION AND CONCLUSION

Gut microbiota may have a causal role in male reproduction health, therapeutic strategies such as supplementation with appropriate probiotics could be undertaken as a complementary treatment. In the future, additional research is needed to demonstrate the links and underlying mechanisms between gut microbiome and male reproduction. This article is protected by copyright. All rights reserved.

Antidepressant mechanism of catalpol: Involvement of the PI3K/Akt/Nrf2/HO-1 signaling pathway in rat hippocampus

Catalpol is a major compound in Rehmanniae Radix with outstanding medicinal and nutritional values. Our previous studies have demonstrated catalpol's antidepressant effect, but its mechanisms remain unclear. This study aimed to explore the antidepressant mechanisms of catalpol via the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/nuclear factor E2-related factor 2(Nrf2)/heme oxygenase-1 (HO-1) pathway. Results demonstrated that chronic unpredictable mild stress (CUMS) for 5 consecutive weeks caused significant decreases in the sucrose preference and the horizontal and vertical scores of open-field test, as well as a significant increase in the swimming-immobility time of rats; catalpol administration significantly reversed the abnormality of these indicators. Further real-time fluorescent quantitative polymerase chain reaction and Western blotting results together showed that CUMS significantly downregulated the expression levels of hippocampal genes and proteins, including PI3K, Akt, Nrf2, HO-1, tropomyosin-related kinase B (TrkB), and brain-derived neurotrophic factor; catalpol administration significantly reversed the abnormal expression of these genes and proteins. CUMS also caused a significant decrease in the hippocampal superoxide dismutase, catalase, glutathione peroxidase, glutathione-s transferase, and reduced glutathione levels, as well as a significant increase in thiobarbituric acid reactive substances level in rats; catalpol administration significantly reversed the abnormality of these indicators. Taken together, this study confirmed for the first time that the antidepressant effect of catalpol on CUMS-induced depression involved the upregulation of the PI3K/Akt/Nrf2/HO-1 signaling pathway, thereby improving the hippocampal neurotrophic, neuroprotective, and antioxidant levels. The PI3K/Akt/Nrf2/HO-1 pathway-related molecules may serve as potential new biomarkers and candidate molecular targets for catalpol's antidepressant effects.