Treatment effect of l-Norvaline on the sexual performance of male rats with streptozotocin induced diabetes

Seminal vesicles - an overlooked pair of accessory glands in male sexual dysfunction: a narrative review

The seminal vesicles (SVs) have long been recognized for their role in male fertility, yet their contribution to male sexual function is often underestimated. In recent decades, studies have gradually unveiled an association between SVs and various male sexual dysfunctions (SDs), including diminished libido, erectile dysfunction, premature ejaculation, delayed ejaculation, and orgasmic disorder. We conducted a comprehensive literature search of publications up until April 2024 in PubMed, Google Scholar, and CNKI, focusing on original studies, case reports, and reviews addressing the relationship between SVs and male SDs. The aim was to explore the pathophysiological mechanisms, clinical evaluation, and management of this relationship, providing urologists and andrologists with new insights into diagnosing and treating complex male SDs. Current research suggests that SVs may play a role in male sexual function, but the evidence remains limited. Future large-scale, rigorously designed studies are needed to further validate this relationship.

Study on the correlation of supplementation with L-citrulline on the gastrointestinal flora and semen antifreeze performance of ram

INTRODUCTION

Cryopreservation of semen can give full play to the reproductive advantages of male animals. However, in actual production, due to the poor frost resistance of sheep semen and the low conception rate, the promotion of sheep frozen semen is greatly hindered. Therefore, it is urgent to improve the frost resistance of semen to improve the quality of frozen semen. At present, most studies on improving the quality of frozen semen are based on the improvement of semen dilutions, and few studies on improving the freezing resistance of ram semen by feeding functional amino acids.

METHODS

Therefore, 24 Turpan black rams were divided into high antifreeze group (HF) and a low antifreeze group (LF) Each of these groups was further randomly divided into control and experimental subgroups. The control subgroup was fed a basal diet, while the experimental subgroup received an additional 12 g/d of L-Cit supplementation based on the control group for a duration of 90 days.

RESULTS

The results showed that Following L-Cit supplementation, the experimental group demonstrated significantly elevated sperm density and VSL (Velocity of straight line), T-AOC, GSH-Px, and NO levels in fresh semen compared to the control group (P < 0.01). After thawing, the experimental group exhibited significantly higher levels of T-AOC, GSH-Px, and NO compared to the control group (P < 0.01). Additionally, the HFT group, after thawing frozen semen, displayed significantly higher HK1 protein expression compared to the control group. The number of spermatogonia, spermatocytes, and sperm cells in the HFT group was significantly higher than that in the HFC group. Moreover, 16S rRNA sequence analysis showed that Candidatus_Saccharimonas, Staphylococcus, Weissella, succinivbrionaceae_UcG_002, and Quinella were significantly enriched in the rumen of the HFT group, while Ureaplasma was significantly enriched in the HFC group. In the duodenum, Clostridiales_bacterium_Firm_14, Butyrivibrio, and Prevotellaceae_NK3831_group were significantly enriched in the HFT group, whereas Desulfovibrio and Quinella were significantly enriched in the HFC group.

DISCUSSION

Under the conditions employed in this study, L-Cit supplementation was found to enhance the intestinal flora composition in rams, thereby improving semen quality, enhancing the antifreeze performance of semen, and promoting the development of testicular spermatogenic cells.

Effects of Spirulina maxima on a Model of Sexual Dysfunction in Streptozotocin-Induced Diabetic Male Rats

Arthrospira (Spirulina) maxima (SM) is a cyanobacterium that has a long history of being used as human food. In recent years, several investigations have shown its beneficial biological effects, among which its antioxidant capacity has been highlighted. The purpose of this study was to evaluate the effects of SM on body weight, glycemia, sexual behavior, sperm quality, testosterone levels, sex organ weights, and the activity of antioxidant enzymes in diabetic male rats (a disease characterized by an increase in reactive oxygen species). The experiment consisted of six groups of sexually expert adult males (n = 6): (1) control (vehicle); (2) streptozotocin (STZ)-65 mg/kg; (3) SM-400 mg/kg; (4) STZ + SM-100 mg/kg; (5) STZ + SM-200 mg/kg; and (6) STZ + SM-400 mg/kg. Sexual behavior tests were performed during the first 3 h of the dark period under dim red illumination. Our results showed that SM significantly improved sexual behavior and sperm quality vs. diabetic animals. Likewise, while the enzymatic activities of SOD and GPx increased, TBARS lipoperoxidation decreased and testosterone levels increased. In view of the findings, it is suggested that SM may potentially be used as a nutraceutical for the treatment of diabetic male sexual dysfunction due to its antioxidant property.

Arginase: Biological and Therapeutic Implications in Diabetes Mellitus and Its Complications

Arginase is a ubiquitous enzyme in the urea cycle (UC) that hydrolyzes L-arginine to urea and L-ornithine. Two mammalian arginase isoforms, arginase1 (ARG1) and arginase2 (ARG2), play a vital role in the regulation of β-cell functions, insulin resistance (IR), and vascular complications via modulating L-arginine metabolism, nitric oxide (NO) production, and inflammatory responses as well as oxidative stress. Basic and clinical studies reveal that abnormal alterations of arginase expression and activity are strongly associated with the onset and development of diabetes mellitus (DM) and its complications. As a result, targeting arginase may be a novel and promising approach for DM treatment. An increasing number of arginase inhibitors, including chemical and natural inhibitors, have been developed and shown to protect against the development of DM and its complications. In this review, we discuss the fundamental features of arginase. Next, the regulatory roles and underlying mechanisms of arginase in the pathogenesis and progression of DM and its complications are explored. Furthermore, we review the development and discuss the challenges of arginase inhibitors in treating DM and its related pathologies.

Neurons for Ejaculation and Factors Affecting Ejaculation

Ejaculation is a reflex and the last stage of intercourse in male mammals. It consists of two coordinated phases, emission and expulsion. The emission phase consists of secretions from the vas deferens, seminal vesicle, prostate, and Cowper's gland. Once these contents reach the posterior urethra, movement of the contents becomes inevitable, followed by the expulsion phase. The urogenital organs are synchronized during this complete event. The L3-L4 (lumbar) segment, the spinal cord region responsible for ejaculation, nerve cell bodies, also called lumbar spinothalamic (LSt) cells, which are denoted as spinal ejaculation generators or lumbar spinothalamic cells [Lst]. Lst cells activation causes ejaculation. These Lst cells coordinate with [autonomic] parasympathetic and sympathetic assistance in ejaculation. The presence of a spinal ejaculatory generator has recently been confirmed in humans. Different types of ejaculatory dysfunction in humans include premature ejaculation (PE), retrograde ejaculation (RE), delayed ejaculation (DE), and anejaculation (AE). The most common form of ejaculatory dysfunction studied is premature ejaculation. The least common forms of ejaculation studied are delayed ejaculation and anejaculation. Despite the confirmation of Lst in humans, there is insufficient research on animals mimicking human ejaculatory dysfunction.

Amelioration of the Abnormalities Associated with Metabolic Syndrome by L-Norvaline in Hyperlipidemic Diabetic Rats

The present study was designed to assess the treatment effect of arginase inhibitor, L-Norvaline in abnormalities associated with high fat diet (HFD) and fructose-induced metabolic syndrome. The HFD and fructose was fed to the rats for a period of 45 days. Animals having body weight of 350 g and fasting blood sugar level of more than 250 mg/dl were considered as hyperlipidemic diabetic rats (HDR) and selected for the study. The HDR were divided into three groups having six animals each. The HDR received L–Norvaline (10 mg/kg/day, i.p.) and standard drug, gemfibrozil (60 mg/kg/day, p.o.), for a period of 30 days. Various hormonal, biochemical and tissue parameters were evaluated at the end of the study. Both treatments significantly decreased body weight, BMI, fasting blood sugar and insulin level and improved insulin resistance in HDR as compared to the toxicant control group. A significant improvement was observed in the lipid profile, levels of nitrate, leptin, C-reactive protein and adiponectin in HDR. L-Norvaline also caused slight decrease in the malondialdehyde level, though, no prominent effect was observed on the level of superoxide dismutase and reduced glutathione in the pancreas of HDR, as compared to the toxicant control group. L-Norvaline treatment also improved the histo-architecture of pancreatic cells. Results of the present study concludes that L-Norvaline caused significant alleviation of the abnormalities of MetS indicating that it can be used as potential treatment strategy for managing the symptoms of metabolic syndrome.

Acute hypoxia elevates arginase 2 and induces polyamine stress response in zebrafish via evolutionarily conserved mechanism

Living organisms repeatedly encounter stressful events and apply various strategies to survive. Polyamines are omnipresent bioactive molecules with multiple functions. Their transient synthesis, inducible by numerous stressful stimuli, is termed the polyamine stress response. Animals developed evolutionarily conserved strategies to cope with stresses. The urea cycle is an ancient attribute that deals with ammonia excess in terrestrial species. Remarkably, most fish retain the urea cycle genes fully expressed during the early stages of development and silenced in adult animals. Environmental challenges instigate urea synthesis in fish despite substantial energetic costs, which poses the question of the urea cycle's evolutionary significance. Arginase plays a critical role in oxidative stress-dependent reactions being the final urea cycle enzyme. Its unique subcellular localization, high inducibility, and several regulation levels provide a supreme ability to control the polyamine synthesis rate. Notably, oxidative stress instigates the arginase-1 activity in mammals. Arginase is also dysregulated in aging organisms' brain and muscle tissues, indicating its role in the pathogenesis of age-associated diseases. We designed a study to investigate the levels of the urea cycle and polyamine synthesis-related enzymes in a fish model of acute hypoxia. We evidence synchronized elevation of arginase-2 and ornithine decarboxylase following oxidative stress in adult fish and aging animals signifying the specific function of arginase-2 in fish. Moreover, we demonstrate oxidative stress-associated polyamine synthesis' induction and urea cycle' arrest in adult fish. The subcellular arginase localization found in the fish seems to correspond to its possible evolutionary roles.

Ejaculatory dysfunction in men with diabetes mellitus

Diabetes mellitus (DM) is a metabolic disorder that is characterized by elevated blood glucose levels due to absolute or relative insulin deficiency, in the background of β-cell dysfunction, insulin resistance, or both. Such chronic hyperglycemia is linked to long-term damage to blood vessels, nerves, and various organs. Currently, the worldwide burden of DM and its complications is in increase. Male sexual dysfunction is one of the famous complications of DM, including abnormal orgasmic/ejaculatory functions, desire/libido, and erection. Ejaculatory dysfunction encompasses several disorders related to DM and its complications, such as premature ejaculation, anejaculation (AE), delayed ejaculation, retrograde ejaculation (RE), ejaculatory pain, anesthetic ejaculation, decreased ejaculate volume, and decreased force of ejaculation. The problems linked to ejaculatory dysfunction may extend beyond the poor quality of life in diabetics as both AE and RE are alleged to alter the fertility potential of these patients. However, although both diabetes patients and their physicians are increasingly aware of diabetic ejaculatory dysfunction, this awareness still lags behind that of other diabetes complications. Therefore, all these disorders should be looked for thoroughly during the clinical evaluation of diabetic men. Besides, introducing the suitable option and/or maneuvers to treat these disorders should be tailored according to each case. This review aimed to explore the most important findings regarding ejaculatory dysfunction in diabetes from pre-clinical and clinical perspectives.

Arginine promotes testicular development in boars through nitric oxide and putrescine

The present work aimed to explore the influence and underlying mechanisms involving arginine in testicular development in boars. To this end, thirty 30-day-old male Duroc piglets (7.00 ± 0.30 kg) were randomly sorted into two groups, maintained on either a basal diet (CON, n = 15) or a diet supplemented with 0.8% arginine (ARG, n = 15). Blood and testicular samples were collected during the experimental period to analyse amino acid composition and arginine metabolite levels. The results showed that dietary supplementation with arginine increased number of spermatogonia and height of the seminiferous epithelium (p < 0.05). Sperm density, total number and effective number of sperm of the boars in the ARG group increased significantly compared with those in the CON group (p < 0.05). Although arginine supplementation did not affect plasma amino acid levels, testicular arginine levels in 150-day-old boars exhibited a significant increase (p < 0.05). The level of serum nitric oxide (NO) and activity of nitric oxide synthase (NOS) also increased in 150-day-old boars in the ARG group (p < 0.05). Interestingly, dietary supplementation with arginine increased testicular levels of putrescine in 150-day-old boars (p < 0.05). These results indicated that arginine supplementation increased serum NO levels and testicular arginine and putrescine abundance, thereby improving testicular development and semen quality in boars.

Early initiation of insulin attenuates histological and functional changes in the liver of streptozotocin-induced diabetic rats using 99mTc-sulfur colloid functional imaging

This study aimed to investigate the effect of insulin on the reticuloendothelial system (RES) in the liver and spleen in diabetic rats. Sprague Dawley rats were divided into control, diabetic rats (DM) and diabetic rats treated with insulin (IDM) for 2 weeks. Rats were imaged with technetium-99m-sulfur colloid (^99mTc-SC) tracer to determine regional distributions of the tracer for all groups by drawing regions of interest and then obtained the ratios as the cumulative counts of heart, liver, and spleen to the whole body (WB). Liver tissue from sacrificed rats from each group was examined by light and electron microscopy. ^99mTc-SC uptake ratios showed a lower liver to WB uptake ratio in the DM rats compared to both controls and IDM rats. Electron microscopy showed severe vacuolization of the hepatocytes of DM rats. The IDM rats show complete resolution of the vacuolization. The early administration of insulin for 2 weeks to diabetic rats could significantly resolve the phagocytic RES function and histological changes in the liver.

Arginase inhibition by (-)-Epicatechin reverses endothelial cell aging

Endothelial dysfunction (EnD) occurs with aging and endothelial nitric oxide (NO) production by NO synthase (NOS) can be impaired. Low NO levels have been linked to increased arginase (Ar) activity as Ar competes with NOS for L-arginine. The inhibition of Ar activity can reverse EnD and (-)-epicatechin (Epi) inhibits myocardial Ar activity. In this study, through in silico modeling we demonstrate that Epi interacts with Ar similarly to its inhibitor Norvaline (Norv). Using in vitro and in vivo models of aging, we examined Epi and Norv-inhibition of Ar activity and its endothelium-protective effects. Bovine coronary artery endothelial cells (BCAEC) were treated with Norv (10 μM), Epi (1 μM) or the combination (Epi + Norv) for 48 h. Ar activity increased in aged BCAEC, with decreased NO generation. Treatment decreased Ar activity to levels seen in young cells. Epi and Epi + Norv decreased nitrosylated Ar levels by ~25% in aged cells with lower oxidative stress (~25%) (dihydroethidium) levels. In aged cells, Epi and Epi + Norv restored the eNOS monomer/dimer ratio, protein expression levels and NO production to those of young cells. Furthermore, using 18 month old rats 15 days of treatment with either Epi (1 mg/kg), Norv (10 mg/kg) or combo, decreased hypertension and improved aorta vasorelaxation to acetylcholine, blood NO levels and tetra/dihydribiopterin ratios in cultured rat aortic endothelial cells. In conclusion, results provide evidence that inhibiting Ar with Epi reverses aged-related loss of eNOS function and improves vascular function through the modulation of Ar and eNOS protein levels and activity.

Proteomic analysis reveals key proteins involved in arginine promotion of testicular development in boars

In order to study the effect of l-arginine on testicular development in boars and its underlying mechanism, thirty 30-day-old Duroc boars (7.0 ± 0.3 kg) were randomly allocated to either a basal diet (CON, n = 15) or a 0.8% arginine diet (ARG, n = 15). Blood samples were collected and weight measurements were done regularly to every pig during the experimental period. Testes were collected for histological and proteomic analysis from 150-day-old boars. Results showed that dietary supplementation with arginine significantly increased testicular weight, the number of spermatogonia, and the height of the seminiferous epithelium (P < 0.05). The serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also significantly increased in the ARG group (P < 0.05). A total of 154 differentially expressed proteins (DEPs) were identified, 76 of them were upregulated and 78 were downregulated. Mainly enriched metabolic pathways were the mTOR and Wnt signaling pathways. Functional annotation suggested that 18 DEPs were related to male reproduction. Western blotting results further validated the results from proteomics. This study may provide new insights into the molecular mechanisms by which arginine promotes male testicular development.

Dual photothermal MDSCs-targeted immunotherapy inhibits lung immunosuppressive metastasis by enhancing T-cell recruitment

Immunosuppressive chemoresistance is a major barrier in lung cancer treatment. However, the immunosuppressive mechanisms responsible for lung cancer cell chemoresistance and tumor relapse are still unknown. In this study, we introduce a model of precise immunosuppressive-based nanotherapy by designing and delivering biocompatible MDSC-targeted nanocarriers (NCs) into the lung tumor microenvironment. This is accomplished by conjugating l-Norvaline and Sunitinib integrated into biodegradable nanosomes in order to facilitate inhibition of tumor-supporting immunosuppression. Findings show that treatment with NCs increased apoptosis and significantly reduced tumor volume and Ki-67 antigen expression respectively. Biodistribution analysis revealed an increase in drug circulation time, as well as a greater accumulation in lung and peripheral tissues. Furthermore, an upregulation of tumor infiltrating lymphocytes expression was observed, especially CD8+ T cells by 27%, and CD4+ T cells by 7% compared to PBS treatment. The presence of CD161+ (NK1.1) cells revealed NK cell activation followed by decreased MDSC infiltration and MDSC subsets were characterized by the reduction of Gr/CD11b cell population in blood and tissue samples. In addition, these nanospheres, showed increased PTT efficiency and tumour targeting ability as evidenced by highly efficient tumour ablation under near infrared (NIR) exposure. Significant tumor reduction was observed due to recruitment of cytotoxic T-lymphocytes, followed by downregulation of immunosuppressive Foxp3+ Treg cells. Taken together, our findings provide a novel nanodrug delivery strategy for the inhibition of MDSC-related immunosuppression in lung tumor microenvironment and provide a new approach for the efficient treatment of metastatic cancer.

Norvaline Reduces Blood Pressure and Induces Diuresis in Rats with Inherited Stress-Induced Arterial Hypertension

Growing evidence suggests that increased arginase activity affects vital bioprocesses in various systems and universally mediates the pathogenesis of numerous metabolic diseases. The adverse effects of arginase are associated with a severe decline in L-arginine bioavailability, which leads to nitric oxide synthase substrate insufficiency, uncoupling, and, eventually, superoxide anion generation and substantial reduction of nitric oxide (NO) synthesis. In cooperation, it contributes to chronic oxidative stress and endothelial dysfunction, which might lead to hypertension and atherosclerosis. Recent preclinical investigations point arginase as a promising therapeutic target in ameliorating metabolic and vascular dysfunctions. In the present study, adult rats with inherited stress-induced arterial hypertension (ISIAH) were used as a model of hypertension. Wistar rats served as normotensive controls. Experimental animals were intraperitoneally administered for seven days with nonproteinogenic amino acid L-norvaline (30 mg/kg/day), which is a potent arginase inhibitor, or with the vehicle. Blood pressure (BP), body weight, and diuresis were monitored. The changes in blood and urine levels of creatinine, urea, and NO metabolites were analyzed. We observed a significant decline in BP and induced diuresis in ISIAH rats following the treatment. The same procedure did not affect the BP of control animals. Remarkably, the treatment had no influence upon glomerular filtration rate in two experimental groups, just like the daily excretion of creatinine and urea. Conversely, NO metabolite levels were amplified in normotonic but not in hypertensive rats following the treatment. The data indicate that L-norvaline is a potential antihypertensive agent and deserves to be clinically investigated. Moreover, we suggest that changes in blood and urine are causally related to the effect of L-norvaline upon BP regulation.

Role of the metabolism of branched-chain amino acids in the development of Alzheimer's disease and other metabolic disorders

Alzheimer’s disease is an incurable chronic neurodegenerative disorder and the leading cause of dementia, imposing a growing economic burden upon society. The disease progression is associated with gradual deposition of amyloid plaques and the formation of neurofibrillary tangles within the brain parenchyma, yet severe dementia is the culminating phase of the enduring pathology. Converging evidence suggests that Alzheimer’s disease-related cognitive decline is the outcome of an extremely complex and persistent pathophysiological process. The disease is characterized by distinctive abnormalities apparent at systemic, histological, macromolecular, and biochemical levels. Moreover, besides the well-defined and self-evident characteristic profuse neurofibrillary tangles, dystrophic neurites, and amyloid-beta deposits, the Alzheimer’s disease-associated pathology includes neuroinflammation, substantial neuronal loss, apoptosis, extensive DNA damage, considerable mitochondrial malfunction, compromised energy metabolism, and chronic oxidative stress. Likewise, distinctive metabolic dysfunction has been named a leading cause and a hallmark of Alzheimer’s disease that is apparent decades prior to disease manifestation. State-of-the-art metabolomics studies demonstrate that altered branched-chain amino acids (BCAAs) metabolism accompanies Alzheimer’s disease development. Lower plasma valine levels are correlated with accelerated cognitive decline, and, conversely, an increase in valine concentration is associated with reduced risk of Alzheimer’s disease. Additionally, a clear BCAAs-related metabolic signature has been identified in subjects with obesity, diabetes, and atherosclerosis. Also, arginine metabolism is dramatically altered in Alzheimer’s disease human brains and animal models. Accordingly, a potential role of the urea cycle in the Alzheimer’s disease development has been hypothesized, and preclinical studies utilizing intervention in the urea cycle and/or BCAAs metabolism have demonstrated clinical potential. Continual failures to offer a competent treatment strategy directed against amyloid-beta or Tau proteins-related lesions, which could face all challenges of the multifaceted Alzheimer’s disease pathology, led to the hypothesis that hyperphosphorylated Tau and deposited amyloid-beta proteins are just hallmarks or epiphenomena, but not the ultimate causes of Alzheimer’s disease. Therefore, approaches targeting amyloid-beta or Tau are not adequate to cure the disease. Accordingly, the modern scientific vision of Alzheimer’s disease etiology and pathogenesis must reach beyond the hallmarks, and look for alternative strategies and areas of research.

Ameliorative effects of Lycium chinensis on male sexual dysfunction and testicular oxidative damage in streptozotocin-induced diabetic rats

The root bark of Lycium chinense (LC) has been reported to have potent antioxidant and antidiabetic properties. In the present study, we investigated the attenuative effect of LC against diabetes induced sexual dysfunction and testicular damages in animal models. Diabetic animals were treated with LC (100 and 400 mg/kg) once daily for 6 weeks. At the end of the treatment, mating behavior tests were performed and the animals were sacrificed for the determination of hormonal profile, oxidative stress indices and sperm analysis. LC administration significantly decreased blood glucose level, enhancement of the antioxidant enzyme activities, restored altered sperm characteristics and markedly improved levels of luteinizing hormone, follicle-stimulating hormone and testosterone as compared to the untreated diabetic animals. Furthermore, LC also improved sperm count, viability, motility, increased the reproductive organs weight. The results obtained indicated that L. chinense has beneficial effects in diabetes sexual dysfunction.

Erectile dysfunction attenuation by naringenin in streptozotocin-induced diabetic rats

Diabetes mellitus is associated with sexual dysfunction, which leads to infertility in animal models. The aim of this study was to evaluate sexual behavior in diabetic rats administered with naringenin. Rats were classified into five groups including healthy controls, those with STZ-induced diabetes, and those with STZ-induced diabetes then treated with 25, 50, or 100 mg kg^-1  day^-1 of naringenin. Male rats were introduced to sexually receptive females, and data were collected regarding sexual behavior and erectile activity. Blood samples were taken and histopathological analyses were carried out. ANOVA and the Student-Newman-Keuls t test were used for statistical comparisons. Sexual behavioral, mount latency, intromission latency, ejaculation latency, and postejaculatory interval were significantly increased in diabetic rates compared with controls (p < 0.001). The NG-treated rats showed a significant improvement in testosterone and cyclic guanosine monophosphate levels, and testicular oxidative stress and inflammatory biomarkers were corrected in a dose-dependent manner compared with controls. The treatment protocol used in this study led to the elimination of sexual impairment resulting from DM, and naringenin showed significant antiinflammatory and antioxidant effects in testicular cells. PRACTICAL APPLICATIONS: Erectile dysfunction occurs in more than 50% of men who are diagnosed with diabetes mellitus. The prevalence of ED is 25% in patients younger than 50 years and 75% in those older than 50 years. Chronic DM leads to oxidative stress, which has significant effects on sexual behavior, spermatogenesis, and sperm biology. Phenolic compounds have been reported to reduce streptozotocin-induced oxidative stress in experimental animal models. In addition, they have significant effects on the generation of sperm (spermatogenesis), which is involved in the pathogenesis of chronic DM. Our study was designed to examine the effect of naringenin, a flavone flavonoid, on oxidative stress, the inflammatory process, sexual behavior, erectile activity through spermatogenesis, and cavernous cyclic guanosine monophosphate in streptozotocin-induced diabetic rats.

Troxerutin affects the male fertility in prepubertal type 1 diabetic male rats

OBJECTIVES

Diabetes can gradually cause damage to the function and structure of male gonads. This survey was conducted to investigate the effect of troxerutin on hormonal changes, serum oxidative stress indices, and testicular function and structure in prepubertal diabetic rats.

MATERIALS AND METHODS

Fifty prepubertal (6 weeks old) male Wistar rats were divided into five groups including Control, Troxerutin, Diabetic, Diabetic+Troxerutin, and Diabetic+Insulin. Type I diabetes was induced by 55 mg/kg of streptozotocin intraperitoneally. The groups were treated with 150 mg/kg/day troxerutin via oral gavage or 4-6 IU/day insulin via subcutaneous injection for 4 consecutive weeks. Blood sugar (BS) and serum levels of insulin, FSH, LH, testosterone, glutathione peroxidase (GPX), superoxide dismutase (SOD), malondialdehyde (MDA), and total antioxidant capacity (TAC) were analyzed. Testis and epididymis were removed for histopathologic study and analysis of sperm parameters.

RESULTS

Troxerutin significantly reduced the BS in the diabetic group similar to insulin but could not affect insulin, FSH, or LH significantly. Troxerutin caused a significant increase in testosterone and GPX but had no significant effect on serum MDA, TAC, and SOD levels. In addition, troxerutin had a better effect than insulin on diabetes-induced testicular structural damage. Sperm analysis results also revealed that troxerutin and insulin could improve sperm number, motility, and viability in diabetic rats.

CONCLUSION

According to these results, it can be derived that administration of troxerutin is a suitable protective strategy for side effects of diabetes in testis of prepubertal diabetic male rats.

Cytotoxicity and mitochondrial dysfunction caused by the dietary supplement l-norvaline

In addition to the 20 protein amino acids that are encoded for protein synthesis, hundreds of other naturally occurring amino acids, known as non-proteinogenic amino acids (NPAAs) exist. It is well known that some NPAAs are toxic through their ability to mimic protein amino acids, either in protein synthesis or in other metabolic pathways, and this property is utilised by some plants to inhibit the growth of other plants or kill herbivores. L-norvaline is an NPAA readily available for purchase as a dietary supplement. In light of previous evidence of l-norvaline's antifungal, antimicrobial and herbicidal activity, we examined the toxicity of l-norvaline to mammalian cells in vitro and showed that l-norvaline decreased cell viability at concentrations as low as 125 μM, caused necrotic cell death and significant changes to mitochondrial morphology and function. Furthermore, toxicity was reduced in the presence of structurally similar 'protein' amino acids, suggesting l-norvaline's cytotoxicity could be attributed to protein amino acid mimicry.

Vitexin alleviates streptozotocin-induced sexual dysfunction and fertility impairments in male mice via modulating the hypothalamus-pituitary-gonadal axis

Diabetes-associated sexual dysfunction and fertility impairments are major secondary complications in diabetic patients and animal models. Natural herbs are important sources of therapeutic agents for diabetic complications. This study investigated the effect of vitexin on male sexual dysfunction and fertility impairments in streptozotocin (STZ)-induced diabetic mice. Diabetes was induced by intraperitoneal injection of 45 mg/kg STZ for 5 consecutive days in mice. Vitexin (10, 20 or 40 mg/kg) and Sildenafil citrate (SC, 5 mg/kg) were administered daily for 62 days after the induction of diabetes. The parameters of sexual behavior and fertility were analyzed. The reproductive organ weight, sperm motility, and viability of the treated mice were examined. Testicular histopathological alterations were detected by hematoxylin and eosin (H&E) staining. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate serum hormonal levels. Results showed that 40 mg/kg vitexin significantly improved the sexual behavior and fertility levels compared with the diabetic group. Moreover, vitexin (20 or 40 mg/kg) significantly increased reproductive organ weight and improved testicular pathological structure damage. Meanwhile, sperm analysis demonstrated that vitexin significantly restored sperm quality in a dose-dependent manner. Furthermore, ELISA data showed that vitexin significantly increased the serum testosterone (T), follicular-stimulating hormone (FSH), and luteinizing hormone (LH) levels but decreased the gonadotropin-releasing hormone (GnRH) level to different degrees. These findings suggest that vitexin ameliorates sexual dysfunction and fertility impairments in male diabetic mice possibly by modulating the hypothalamus-pituitary-gonadal axis.

Arginase: A Multifaceted Enzyme Important in Health and Disease

The arginase enzyme developed in early life forms and was maintained during evolution. As the last step in the urea cycle, arginase cleaves l-arginine to form urea and l-ornithine. The urea cycle provides protection against excess ammonia, while l-ornithine is needed for cell proliferation, collagen formation, and other physiological functions. In mammals, increases in arginase activity have been linked to dysfunction and pathologies of the cardiovascular system, kidney, and central nervous system and also to dysfunction of the immune system and cancer. Two important aspects of the excessive activity of arginase may be involved in diseases. First, overly active arginase can reduce the supply of l-arginine needed for the production of nitric oxide (NO) by NO synthase. Second, too much l-ornithine can lead to structural problems in the vasculature, neuronal toxicity, and abnormal growth of tumor cells. Seminal studies have demonstrated that increased formation of reactive oxygen species and key inflammatory mediators promote this pathological elevation of arginase activity. Here, we review the involvement of arginase in diseases affecting the cardiovascular, renal, and central nervous system and cancer and discuss the value of therapies targeting the elevated activity of arginase.

Pharmacokinetics and Pharmacodynamics of Promising Arginase Inhibitors

Up-regulation of arginase activity in several chronic disease conditions, including cancer and hypertension, may suggest new targets for treatment. Recently, the number of new arginase inhibitors with promising therapeutic effects for asthma, cancer, hypertension, diabetes mellitus, and erectile dysfunction has shown a remarkable increase. Arginase inhibitors may be chemical substances, such as boron-based amino acid derivatives, α-difluoromethylornithine (DMFO), and Nω-hydroxy-nor-L-arginine (nor-NOHA) or, of plant origin such as sauchinone, salvianolic acid B (SAB), piceatannol-3-O-β-D-glucopyranoside (PG) and obacunone. Despite their promising therapeutic potential, little is known about pharmacokinetics and pharmacodynamics of some of these agents. Several studies were conducted in different animal species and in vitro systems and reported significant differences in pharmacokinetics and pharmacodynamics of arginase inhibitors. Therefore, extra caution should be considered before extrapolating these studies to human. Physicochemical and pharmacokinetic profiles of some effective arginase inhibitors make it challenging to formulate stable and effective formulation. In this article, existing literature on the pharmacokinetics and pharmacodynamics of arginase inhibitors were reviewed and compared together with emphasis on possible drug interactions and solutions to overcome pharmacokinetics challenges and shortage of arginase inhibitors in clinical practice.

Rice Bran Metabolome Contains Amino Acids, Vitamins & Cofactors, and Phytochemicals with Medicinal and Nutritional Properties

BACKGROUND

Rice bran is a functional food that has shown protection against major chronic diseases (e.g. obesity, diabetes, cardiovascular disease and cancer) in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals. Food metabolomics uses multiple chromatography and mass spectrometry platforms to detect and identify a diverse range of small molecules with high sensitivity and precision, and has not been completed for rice bran.

RESULTS

This study utilized global, non-targeted metabolomics to identify small molecules in rice bran, and conducted a comprehensive search of peer-reviewed literature to determine bioactive compounds. Three U.S. rice varieties (Calrose, Dixiebelle, and Neptune), that have been used for human dietary intervention trials, were assessed herein for bioactive compounds that have disease control and prevention properties. The profiling of rice bran by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) identified 453 distinct phytochemicals, 209 of which were classified as amino acids, cofactors & vitamins, and secondary metabolites, and were further assessed for bioactivity. A scientific literature search revealed 65 compounds with health properties, 16 of which had not been previously identified in rice bran. This suite of amino acids, cofactors & vitamins, and secondary metabolites comprised 46% of the identified rice bran metabolome, which substantially enhanced our knowledge of health-promoting rice bran compounds provided during dietary supplementation.

CONCLUSION

Rice bran metabolite profiling revealed a suite of biochemical molecules that can be further investigated and exploited for multiple nutritional therapies and medical food applications. These bioactive compounds may also be biomarkers of dietary rice bran intake. The medicinal compounds associated with rice bran can function as a network across metabolic pathways and this metabolite network may occur via additive and synergistic effects between compounds in the food matrix.

Translational Perspective on the Role of Testosterone in Sexual Function and Dysfunction

INTRODUCTION

The biological importance of testosterone is generally accepted by the medical community; however, controversy focuses on its relevance to sexual function and the sexual response, and our understanding of the extent of its role in this area is evolving.

AIM

To provide scientific evidence examining the role of testosterone at the cellular and molecular levels as it pertains to normal erectile physiology and the development of erectile dysfunction and to assist in guiding successful therapeutic interventions for androgen-dependent sexual dysfunction.

METHODS

In this White Paper, the Basic Science Committee of the Sexual Medicine Society of North America assessed the current basic science literature examining the role of testosterone in sexual function and dysfunction.

RESULTS

Testosterone plays an important role in sexual function through multiple processes: physiologic (stimulates activity of nitric oxide synthase), developmental (establishes and maintains the structural and functional integrity of the penis), neural (development, maintenance, function, and plasticity of the cavernous nerve and pelvic ganglia), therapeutically for dysfunctional regulation (beneficial effect on aging, diabetes, and prostatectomy), and phosphodiesterase type 5 inhibition (testosterone supplement to counteract phosphodiesterase type 5 inhibitor resistance).

CONCLUSION

Despite controversies concerning testosterone with regard to sexual function, basic science studies provide incontrovertible evidence for a significant role of testosterone in sexual function and suggest that properly administered testosterone therapy is potentially advantageous for treating male sexual dysfunction.

Effect of Kaempferia parviflora on sexual performance in streptozotocin-induced diabetic male rats

Kaempferia parviflora Wall. Ex.Baker or Krachidum (KP) has been used locally in medicine and food. It has been claimed that KP has aphrodisia properties; however, no scientific data in support of this function in diabetic model have been reported. This study aimed to investigate the efficacy of KP on sexual behaviour and sperm parameter in streptozotocin (STZ)-induced diabetic male rats. Diabetes was induced in twenty male rats by STZ and divided into four groups: diabetic control group, and 3 treatment groups where KP was dose at 140, 280 and 420 mg/kg orally once a day for 6 weeks. Five normal control rats were treated with vehicle. The body weight, blood glucose, food intake, epididymal sperm parameter, sexual behaviour and serum testosterone level were evaluated. The results showed that KP treatment has no effect on the body weight, blood glucose and food intake in diabetic rats. A significant increase in sperm density in diabetic rats was observed (p < .05) at highest dose of KP. Furthermore, KP treatment demonstrated a significant recovery of sexual behaviour and serum testosterone levels in diabetic rats. These results confirm that KP exhibits aphrodisiac properties that improve the sperm density, testosterone level and sexual performance of STZ-induced diabetic rats.