Hyperglycemia is associated with reduced testicular function and activin dysregulation in the Ins2Akita+/- mouse model of type 1 diabetes

Naringin from sweet orange peel improves testicular function in high fat diet-induced diabetic rats by modulating xanthine oxidase/uric acid signaling and maintaining redox balance

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a metabolic disorder affecting many organs, including the testis. Naringin from orange peel extract (OPE) is a flavanone with fertility-enhancing properties. Hence, this study was designed to establish the effect of naringin on T2DM-induced testicular dysfunction. Thirty male (30) Wistar rats were randomized into five groups control, diabetes, diabetes + naringin, diabetes + OPE, and diabetes + metformin. The administrations were via the oral route and lasted for 28 days.

RESULTS

Naringin ameliorated T2DM-induced increase in FBS and decrease in serum insulin. It also abrogated T2DM-induced decrease in sperm quality, gonadotropin-releasing hormone, luteinizing hormone, follicle-stimulating hormone, testosterone, estradiol, prolactin, catalase, superoxide dismutase, and total antioxidant capacity. Furthermore, naringin prevented a T2DM-induced increase in malonaldehyde, tumor necrosis factor-alpha, C-reactive protein, xanthine oxidase (XO), and uric acid (UA), it was accompanied by the restoration of normal testicular histoarchitecture.

CONCLUSIONS

Naringin prevented T2DM-induced testicular dysfunction by modulating XO/UA and restoring redox balance. Also, while the animals treated with OPE exhibited better ameliorative effects than their counterparts treated with naringin, the findings from this study showed that naringin would be a promising supplement for treating T2DM-induced male infertility.

The protective effects of icariin against testicular dysfunction in type 1 diabetic mice Via AMPK-mediated Nrf2 activation and NF-κB p65 inhibition

BACKGROUND

Owing to the early suffering age and the rising incidence of type 1 diabetes (T1D), the resulting male reproductive dysfunction and fertility decline have become a disturbing reality worldwide, with no effective strategy being available. Icariin (ICA), a flavonoid extracted from Herba Epimedium, has been proved its promising application in improving diabetes-related complications including diabetic nephropathy, endothelial dysfunction and erectile dysfunction. Ensuring the future reproductive health of children and adolescents with T1D is crucial to improve global fertility. However, its roles in the treatment of T1D-induced testicular dysfunction and the potential mechanisms remain elusive.

PURPOSE

The purpose of this present study was to investigate whether ICA ameliorates T1D-induced testicular dysfunction as well as its potential mechanisms.

METHODS

T1D murine model was established by intraperitoneal injection of STZ with or without treated with ICA for eleven weeks. Morphological, pathological and serological experiments were used to determine the efficacy of ICA on male reproductive function of T1D mice. Western blotting, Immunohistochemistry analysis, qRT-PCR and kit determination were performed to investigated the underlying mechanisms.

RESULTS

We found that replenishment of ICA alleviated testicular damage, promoted testosterone production and spermatogenesis, ameliorated apoptosis and blood testis barrier impairment in streptozotocin-induced T1D mice. Functionally, ICA treatment triggered adenosine monophosphate protein kinase (AMPK) activation, which in turn inhibited the nuclear translocation of nuclear factor kappa B p65 (NF-κB p65) to reduce inflammatory responses in the testis and activated nuclear factor erythroid 2-related factor 2(Nrf2), thereby enhancing testicular antioxidant capacity. Further studies revealed that supplementation with the AMPK antagonist Compound C or depletion of Nrf2 weakened the beneficial effects of ICA on testicular dysfunction of T1D mice.

CONCLUSION

Collectively, these results demonstrate the feasibility of ICA in the treatment of T1D-induced testicular dysfunction, and reveal the important role of AMPK-mediated Nrf2 activation and NF-κB p65 inhibition in ICA-associated testicular protection during T1D.

Follistatin and follistatin-like 3 in metabolic disorders

Follistatin (FST) is a glycoprotein which main role is antagonizing activity of transforming growth factor β superfamily members. Folistatin-related proteins such as follistatin-like 3 (FSTL3) also reveal these properties. The exact function of them has still not been established, but it can be bound to the pathogenesis of metabolic disorders. So far, there were performed a few studies about their role in type 2 diabetes, obesity or gestational diabetes and even less in type 1 diabetes. The outcomes are contradictory and do not allow to draw exact conclusions. In this article we summarize the available information about connections between follistatin, as well as follistatin-like 3, and metabolic disorders. We also emphasize the strong need of performing further research to explain their exact role, especially in the pathogenesis of diabetes and obesity.

Combination Therapy with Enalapril and Paricalcitol Ameliorates Streptozotocin Diabetes-Induced Testicular Dysfunction in Rats via Mitigation of Inflammation, Apoptosis, and Oxidative Stress

BACKGROUND

As the impacts of diabetes-induced reproductive damage are now evident in young people, we are now in urgent need to devise new ways to protect and enhance the reproductive health of diabetic people. The present study aimed to evaluate the protective effects of enalapril (an ACE inhibitor) and paricalcitol (a vitamin D analog), individually or in combination, on streptozotocin (STZ)-diabetes-induced testicular dysfunction in rats and to identify the possible mechanisms for this protection.

MATERIAL AND METHODS

This study was carried out on 50 male Sprague-Dawley rats; 10 normal rats were allocated as a non-diabetic control group. A total of 40 rats developed diabetes after receiving a single dose of STZ; then, the diabetic rats were divided into four groups of equivalent numbers assigned as diabetic control, enalapril-treated, paricalcitol-treated, and combined enalapril-and-paricalcitol-treated groups. The effects of mono and combined therapy with paricalcitol and enalapril on testicular functions, sperm activity, glycemic state oxidative stress, and inflammatory parameters, as well as histopathological examinations, were assessed in comparison with the normal and diabetic control rats.

RESULTS

As a result of diabetes induction, epididymal sperm count, sperm motility, serum levels of testosterone, follicle-stimulating hormone (FSH) as well as luteinizing hormone (LH), and the antioxidant enzyme activities, were significantly decreased, while abnormal sperm (%), insulin resistance, nitric oxide (NO), malondialdehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were significantly increased, along with severe distortion of the testicular structure. Interestingly, treatment with paricalcitol and enalapril, either alone or in combination, significantly improved the sperm parameters, increased antioxidant enzyme activities in addition to serum levels of testosterone, FSH, and LH, reduced insulin resistance, IL-6, and TNF-α levels, and finally ameliorated the diabetes-induced testicular oxidative stress and histopathological damage, with somewhat superior effect for paricalcitol monotherapy and combined therapy with both drugs compared to monotherapy with enalapril alone.

CONCLUSIONS

Monotherapy with paricalcitol and its combination therapy with enalapril has a somewhat superior effect in improving diabetes-induced testicular dysfunction (most probably as a result of their hypoglycemic, antioxidant, anti-inflammatory, and anti-apoptotic properties) compared with monotherapy with enalapril alone in male rats, recommending a synergistic impact of both drugs.

Chromium Picolinate Protects against Testicular Damage in STZ-Induced Diabetic Rats via Anti-Inflammation, Anti-Oxidation, Inhibiting Apoptosis, and Regulating the TGF-β1/Smad Pathway

Chromium picolinate (CP) is an organic compound that has long been used to treat diabetes. Our previous studies found CP could relieve diabetic nephropathy. Thus, we speculate that it might have a positive effect on diabetic testicular injury. In this study, a diabetic rat model was established, and then the rats were treated with CP for 8 weeks. We found that the levels of blood glucose, food, and water intake were reduced, and body weight was enhanced in diabetic rats after CP supplementation. Meanwhile, in CP treatment groups, the levels of male hormone and sperm parameters were improved, the pathological structure of the testicular tissue was repaired, and testicular fibrosis was inhibited. In addition, CP reduced the levels of serum inflammatory cytokines, and decreased oxidative stress and apoptosis in the testicular tissue. In conclusion, CP could ameliorate testicular damage in diabetic rats, as well as being a potential testicle-protective nutrient in the future to prevent the testicular damage caused by diabetes.

Betaine regulates steroidogenesis, endoplasmic reticulum stress response and Nrf2/HO-1 antioxidant pathways in mouse Leydig cells under hyperglycaemia condition

We studied the effects of betaine on steroidogenesis, endoplasmic reticulum stress and Nrf2 antioxidant pathways of mice Leydig cells under hyperglycaemia conditions. Leydig cells were grown in low and high glucose concentrations (5 mM and 30 mM) in the presence of 5 mM of betaine for 24 h. Gene expression was determined using a real-time PCR method. The protein levels were determined by Western blot analysis. The testosterone production was evaluated by the ELISA method. Cellular contents of reduced and oxidised glutathione were measured by colorimetric method. Hyperglycaemia caused impaired steroidogenesis and ERS in Leydig cells associated with the down-regulation of 3β-HSD, StAR, P450scc, LH receptor and increased expression of GRP78, CHOP, ATF6 and IRE1. Betaine could improve cell viability, attenuate the ERS, and restore testosterone production in Leydig cells under hyperglycaemia conditions. Betaine can protect Leydig cells against the adverse effects of hyperglycaemia by regulating steroidogenesis, antioxidants, and ERS.

Ameliorative effect of Stevia rebaudiana Bertoni on sperm parameters, in vitro fertilization, and early embryo development in a streptozotocin-induced mouse model of diabetes

Diabetes mellitus (DM) is a common metabolic disease characterized by high blood sugar levels. It is well known that men with diabetes frequently experience reproductive disorders and sexual dysfunction. In fact, sperm quality has a significant effect on fertilization success and embryo development. The current study aimed to investigate the effect of Stevia rebaudiana hydroalcoholic extract on serum testosterone levels, sperm parameters, in vitro fertilization (IVF) success, and in vitro embryonic developmental potential to reach the blastocyst stage in a streptozotocin (STZ)-induced mouse model of diabetes. In this research, 30 male mice were distributed randomly into control, diabetic (streptozotocin 150 mg/kg) and diabetic + Stevia (400 mg/kg) groups. The results revealed a decrease in body and testis weight and elevated blood fasting blood sugar (FBS) levels in the diabetic group, compared with the control. However, Stevia treatment significantly increased body and testis weight, while serum FBS levels were decreased compared with the diabetic group. In addition, Stevia significantly increased blood testosterone levels compared with the diabetic group. Moreover, sperm parameters were improved considerably by Stevia treatment compared with the diabetic group. Furthermore, Stevia administration significantly promoted IVF success rate and in vitro development of fertilized oocytes compared with the diabetic group. In summary, our data indicated that Stevia enhanced sperm parameters, IVF success, and in vitro embryonic developmental competency in diabetic mice, probably because of its antioxidant effects. Therefore, Stevia could ameliorate sperm parameters that, in turn, increase fertilization outcomes in experimental-induced diabetes.

Potential Mechanism of Platelet-rich Plasma Treatment on Testicular Problems Related to Diabetes Mellitus

Diabetes mellitus is a condition of continuously increased blood glucose levels that causes hyperglycemia. This condition can result in disorders of various organs including testicular problems. The use of platelet-rich plasma (PRP) which is contained in several growth factors shows its potential in overcoming testicular problems. This literature review study was conducted to identify the potential of PRP in overcoming various testicular problems due to diabetic conditions.

Investigating the therapeutic options for diabetes-associated male infertility as illustrated in animal experimental models

Diabetes is a rising global health concern and an increasingly common cause of male infertility. Although the definitive pathophysiological mechanisms underpinning the association between diabetes and infertility is unclear, there are several animal studies showing diabetes to be a detrimental factor on reproductive health through apoptosis, oxidative stress and impairment of steroidogenesis. Furthermore, as reflected in animal models, antidiabetic strategies and relevant treatments are beneficial in the management of infertile men with diabetes as the recovery of euglycemic status affects positively the spermatogenesis. However, the available data are still evolving and specific conclusion in human populations are not possible yet. In this review, we are discussing the current literature concerning the association of diabetes and male infertility, focusing on the therapeutic approach as illustrated in animals' models.

Testicular ultrastructure and hormonal changes following administration of tenofovir disoproxil fumarate-loaded silver nanoparticle in type-2 diabetic rats

Reproductive dysfunctions (RDs) characterized by impairment in testicular parameters, and metabolic disorders such as insulin resistance and type 2 diabetes mellitus (T2DM) are on the rise among human immunodeficiency virus (HIV) patients under tenofovir disoproxil fumarate (TDF) and highly active antiretroviral therapy (HAART). These adverse effects require a nanoparticle delivery system to circumvent biological barriers and ensure adequate ARVDs to viral reservoir sites like testis. This study aimed to investigate the effect of TDF-loaded silver nanoparticles (AgNPs), TDF-AgNPs on sperm quality, hormonal profile, insulin-like growth factor 1 (IGF-1), and testicular ultrastructure in diabetic rats, a result of which could cater for the neglected reproductive and metabolic dysfunctions in HIV therapeutic modality. Thirty-six adult Sprague–Dawley rats were assigned to diabetic and non-diabetic (n = 18). T2DM was induced by fructose-streptozotocin (Frt-STZ) rat model. Subsequently, the rats in both groups were subdivided into three groups each (n = 6) and administered distilled water, TDF, and TDF-AgNP. In this study, administration of TDF-AgNP to diabetic rats significantly reduced (p < 0.05) blood glucose level (268.7 ± 10.8 mg/dL) from 429 ± 16.9 mg/dL in diabetic control and prevented a drastic reduction in sperm count and viability. More so, TDF-AgNP significantly increased (p < 0.05) Gonadotropin-Releasing Hormone (1114.3 ± 112.6 µg), Follicle Stimulating Hormone (13.2 ± 1.5 IU/L), Luteinizing Hormone (140.7 ± 15.2 IU/L), testosterone (0.2 ± 0.02 ng/L), and IGF-1 (1564.0 ± 81.6 ng/mL) compared to their respective diabetic controls (383.4 ± 63.3, 6.1 ± 1.2, 76.1 ± 9.1, 0.1 ± 0.01, 769.4 ± 83.7). Also, TDF-AgNP treated diabetic rats presented an improved testicular architecture marked with the thickened basement membrane, degenerated Sertoli cells, spermatogenic cells, and axoneme. This study has demonstrated that administration of TDF-AgNPs restored the function of hypothalamic-pituitary–gonadal axis, normalized the hormonal profile, enhanced testicular function and structure to alleviate reproductive dysfunctions in diabetic rats. This is the first study to conjugate TDF with AgNPs and examined its effects on reproductive indices, local gonadal factor and testicular ultrastructure in male diabetic rats with the potential to cater for neglected reproductive dysfunction in HIV therapeutic modality.

Diabetes as a potential compounding factor in COVID-19-mediated male subfertility

Recent work indicates that male fertility is compromised by SARS-CoV-2 infection. Direct effects derive from the presence of viral entry receptors (ACE2 and/or CD147) on the surface of testicular cells, such as spermatocytes, Sertoli cells, and Leydig cells. Indirect effects on testis and concentrations of male reproductive hormones derive from (1) virus-stimulated inflammation; (2) viral-induced diabetes, and (3) an interaction between diabetes and inflammation that exacerbates the deleterious effect of each perturbation. Reproductive hormones affected include testosterone, luteinizing hormone, and follicle-stimulating hormone. Reduction of male fertility is also observed with other viral infections, but the global pandemic of COVID-19 makes demographic and public health implications of reduced male fertility of major concern, especially if it occurs in the absence of serious symptoms that would otherwise encourage vaccination. Clinical documentation of COVID-19-associated male subfertility is now warranted to obtain quantitative relationships between infection severity and subfertility; mechanistic studies using animal models may reveal ways to mitigate the problem. In the meantime, the possibility of subfertility due to COVID-19 should enter considerations of vaccine hesitancy by reproductive-age males.

Physalis pubescens L. alleviates testicular disruptions associated with streptozotocin-induced diabetes in male Wistar rats, Rattus norvegicus

Testicular impairment is a serious complication of diabetes that is mediated by oxidative stress and inflammation. Physalis has antioxidative and anti-inflammatory actions. Thus, the present study investigated the ameliorative role of Physalis juice (PJ) prepared from the fruits against testicular damages in streptozotocin (STZ)-induced diabetic rats. Adult male Wistar rats were divided randomly into five groups (n=6): control, orally administered 5 mL PJ/kg daily (PJ), injected intraperitoneally with a single dose of 55 mg STZ/kg without treatment (STZ), or treated daily with PJ (STZ+PJ) or with 500 mg metformin/kg (STZ+Met), for 28 days. The STZ group showed a marked elevation in the blood glucose level by 230%, whereas remarkable declines in the serum levels of testosterone (44%), follicle-stimulating hormone (FSH) (48%), and luteinizing hormone (LH) (36%), as compared to controls. In comparison to controls, the testis of the STZ group showed remarkable declines in the testis weight (15%), the glutathione (GSH) content (45%), mRNA and protein levels of B-cell lymphoma-2 (Bcl-2) (48 and 35%), mRNA and activities of superoxide dismutase (SOD) (63 and 40%), catalase (CAT) (56 and 31%), glutathione peroxidase (GPx) (51 and 44%), and glutathione reductase (GR) (62 and 43%), whereas marked elevations in the levels of interleukin-1 beta (IL-1β (169%), tumor necrosis factor-alfa (TNFα) (85%), nitric oxide (NO) (96%), malondialdehyde (MDA) (83%), mRNA and protein levels of Bcl-2-associated X protein (Bax) (400 and 61%), and mRNA level of caspase-3 (Cas-3) (370%). Some histopathological alterations were observed in the testicular tissue of the STZ group. In contrast, PJ markedly alleviated all the abovementioned disturbances. In conclusion, PJ at a dose of 5 mL/kg attenuated the diabetes-associated testicular impairments, which may be due to its antioxidative, anti-inflammatory, and antiapoptotic actions.

Gain-of-Function Lrp5 Mutation Improves Bone Mass and Strength and Delays Hyperglycemia in a Mouse Model of Insulin-Deficient Diabetes

High fracture rate and high circulating levels of the Wnt inhibitor, sclerostin, have been reported in diabetic patients. We studied the effects of Wnt signaling activation on bone health in a mouse model of insulin-deficient diabetes. We introduced the sclerostin-resistant Lrp5^A214V mutation, associated with high bone mass, in mice carrying the Ins2^Akita mutation (Akita), which results in loss of beta cells, insulin deficiency, and diabetes in males. Akita mice accrue less trabecular bone mass with age relative to wild type (WT). Double heterozygous Lrp5^A214V /Akita mutants have high trabecular bone mass and cortical thickness relative to WT animals, as do Lrp5^A214V single mutants. Likewise, the Lrp5^A214V mutation prevents deterioration of biomechanical properties occurring in Akita mice. Notably, Lrp5^A214V /Akita mice develop fasting hyperglycemia and glucose intolerance with a delay relative to Akita mice (7 to 8 vs. 5 to 6 weeks, respectively), despite lack of insulin production in both groups by 6 weeks of age. Although insulin sensitivity is partially preserved in double heterozygous Lrp5^A214V /Akita relative to Akita mutants up to 30 weeks of age, insulin-dependent phosphorylated protein kinase B (pAKT) activation in vitro is not altered by the Lrp5^A214V mutation. Although white adipose tissue depots are equally reduced in both compound and Akita mice, the Lrp5^A214V mutation prevents brown adipose tissue whitening that occurs in Akita mice. Thus, hyperactivation of Lrp5-dependent signaling fully protects bone mass and strength in prolonged hyperglycemia and improves peripheral glucose metabolism in an insulin independent manner. Wnt signaling activation represents an ideal therapeutic approach for diabetic patients at high risk of fracture. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Expression and localization of apelin and its receptor in the testes of diabetic mice and its possible role in steroidogenesis

Type 1 diabetes mellitus (T1DM) is a metabolic disorder with severe hyperglycemia, one of the complications of which is testicular dysfunctions, androgen deficiency and decreased male fertility. In the diabetic testes, the expression and signaling pathways of leptin and a number of other adipokines are significantly changed. However, there is no information on the localization and expression of adipokine, apelin and its receptor (APJ) in the diabetic testes, although there is information on the involvement of apelin in the regulation of reproductive functions. The aim of this study was to investigate the expression and localization of apelin and APJ in the testes of mice with streptozotocin-induced T1DM and to estimate the effects of agonist (apelin-13) and antagonist (ML221) of APJ on the testosterone production by diabetic testis explants in the in vitro conditions. We first detected the expression of apelin and its receptor in the mouse testes, and showed an increased intratesticular expression of apelin and APJ along with the reduced testosterone secretion in T1DM. Using imunohistochemical approach, we showed that apelin and APJ are localized in the Leydig and germ cells, and in diabetes, the amount of these proteins was significantly higher than in the control mice. The diabetic testes had a decrease in germ cell proliferation (the reduced PCNA and GCNA levels) and an increase in apoptosis (the increased active caspase-3 and decreased BCL2 levels). These results suggest an involvement of apelin and APJ in T1DM-induced testicular pathogenesis. Treatment of the cultured testis explants with ML221 significantly increased the testosterone secretion, whereas apelin-13 was ineffective. Thus, hyperapelinemia in the testes can significantly contribute to testicular pathogenesis in T1DM, and pharmacological inhibition of apelin receptors can improve testicular steroidogenesis.

Protective effects of ethyl acetate extract from Shorea roxburghii against diabetes induced testicular damage in rats

Diabetic mellitus is a chronic metabolic disorder that is associated with several complications including testicular dysfunction. This research investigated the protective action of the ethyl acetate extract from Shorea roxburghii (SRE) on diabetes induced testicular damage in rats. Diabetic rats were orally administered with SRE at doses of 100 and 400 mg/kg for 4 weeks. SRE improved the body weight gain, testes weight, testes index and increased serum concentration of testosterone. Furthermore, SRE increased the testicular antioxidant enzymes including superoxide dismutase, catalase and glutathione peroxidase. In addition, SRE ameliorated testicular inflammatory mediators such as myeloperoxidase, tumor necrosis factor alpha, interleukin 6, p38 MAPK and nuclear factor kappa B activation and decreased testicular cell apoptosis in the treated diabetic rats. SRE also raised sperm parameters after treatment of diabetic rats. Conclusively, our results suggested that SRE ameliorated diabetes induced testicular damage by inhibiting oxidative stress and inflammation.

Rescue effect of sodium acetate in diabetes mellitus-associated testicular dysfunction is accompanied by PCSK9 modulation

Diabetes mellitus (DM) is a global health burden, affecting about 463 million of the adult population worldwide. Approximately 94% of diabetic male individuals develop varying degrees of testicular disorders (TDs), which usually result in hypogonadism, hypotestosteronemia and defective spermatogenesis and steroidogenesis. Short chain fatty acids (SCFAs) have shown potential benefits in metabolic health. However, its effect on TD associated with DM is not clear. Howbeit, the present study investigated the hypothesis that SCFAs, acetate would ameliorate TD accompanying DM, possibly by suppressing proprotein convertase subtilisin/kexin type 9 (PCSK9). Male Wistar rats (210-240 g) were allotted into groups (n = 6/group): control (vehicle; po), DM with/without 200 mg/kg (po) of sodium acetate (SAc). Diabetes was induced by streptozotocin 65 mg/kg (iv) after a dose of nicotinamide (110 mg/kg). Semen/biochemical and histological analyses were performed with appropriate methods. In addition to hyperglycemia, hyperinsulinemia and reduced insulin sensitivity, DM led to increased serum and testicular triglyceride or total cholesterol/high-density lipoprotein cholesterol ratio, low-density lipoprotein cholesterol, malondialdehyde, TNF-α, IL-6 and PCSK9 as well as reduced high-density lipoprotein cholesterol and glutathione. Moreover, DM caused TD which is characterized by altered sperm parameters, disrupted tissue architecture, atrophied seminiferous tubules, deleterious spermatogonia, disappearance of lumen and cellular degeneration as well as decreased luteinizing hormone and testosterone. However, the administration of SAc attenuated these alterations. The study demonstrates that DM-induced TD is accompanied by elevated PCSK9. The results however suggest that SAc rescues testicular disorder/dysfunction associated with DM by suppression of PCSK9 and improvement of insulin sensitivity.

Neutral effect of exenatide on serum testosterone in men with type 2 diabetes mellitus: A prospective cohort

BACKGROUND

Endogenous testosterone increases with weight loss from diet, exercise, and bariatric surgery. However, little is known about testosterone levels after weight loss from medication.

OBJECTIVES

Uncover the effects of Glucagon-Like Peptide-1 receptor agonist (GLP-1 RA) therapy on serum testosterone.

MATERIAL AND METHODS

Prospective cohort study of men starting GLP-1 RA therapy for type 2 diabetes mellitus.

RESULTS

51 men lost 2.27 kg (p = 0.00162) and their HbA1c values improved by 0.7% (p = 0.000503) after 6 months of GLP-1 RA therapy. There was no significant change in testosterone for the group as a whole. However, in subgroup analyses, there was a significant difference in total testosterone change between men starting with baseline total testosterone <320 ng/dL (238.5 ± 56.5 ng/dL to 272.2 ± 82.3 ng/dL) compared to higher values (438 ± 98.2 ng/dL to 412 ± 141.2 ng/dL) (p = 0.0172);free testosterone increased if the baseline total testosterone was <320 ng/dL (55.2 ± 12.8 pg/mL to 57.2 ± 17.6 pg/mL) and decreased if >320 ng/dL (74.7 ± 16.3 pg/mL to 64.2 ± 17.7 pg/mL) (p = 0.00807). Additionally, there were significant differences in testosterone change between men with HbA1c improvements ≥1% (351.6 ± 123.9 ng/dL to 394.4 ± 136.5 ng/dL) compared to men with HbA1c changes <1% (331.8 ± 128.6 ng/dL to 316.1 ± 126.2 ng/dL) (p = 0.0413).

CONCLUSION

GLP-1 RA therapy improves weight and HbA1c without adverse effects on testosterone. Those starting with lower testosterone values or attaining greater improvement in HbA1c may see additional benefits.

The effect of streptozotocin induced diabetes on sperm function: a closer look at AGEs, RAGEs, MAPKs and activation of the apoptotic pathway

This study was designed to (1) investigate the possible mechanisms through which diabetes-induced advanced glycation end products (AGEs) and receptor for AGEs (RAGE) activation can affect male reproductive function; and (2) corroborate the interaction of previously established independent pathways. Male albino Wistar rats (14-weeks old) weighing 250-300 g received either a single intraperitoneal injection of streptozotocin (30 mg/kg or 60 mg/kg), represented as STZ30 or STZ60 respectively, or citrate buffer (control). Diabetes mellitus (DM) was confirmed if plasma glucose levels were ≥ 14 mmol/L after 1 week. Animals were sacrificed after 8 weeks of treatment by an overdose of sodium pentobarbital (160 mg/kg body weight). The testes and epididymides were harvested. The testes were used for biochemical and Western blot analysis, while sperm was retrieved from the epididymis and analysed with computer-aided sperm analysis. The blood glucose levels of STZ60 animals were above the cut-off point and hence these animals were regarded as diabetic. Diabetic animals presented with a non-significant increase in AGE and RAGE expression. Diabetic animals showed a significant increase in the expression of cleaved caspase 3 compared to control (p < 0.001), and these animals also presented with an increase in the expression of JNK (p < 0.05), PARP (p = 0.059) and p38 MAPK (p = 0.1). Diabetic animals also displayed decreased catalase activity accompanied by a non-significant increase in malondialdehyde levels. Additionally, there was a significant decrease in the percentage of progressively motile spermatozoa (p < 0.05) in diabetic animals. This study has shed some light on the interplay between DM, AGE, RAGE and mitogen-activated protein kinase signalling in the testes of diabetic rats, which can result in altered sperm function and contribute to male infertility. However, more studies are needed to better understand this complicated process.

Glutathione (GSH) improves sperm quality and testicular morphology in streptozotocin-induced diabetic mice

Diabetes mellitus (DM) is known to cause reproductive impairment. In men, it has been linked to altered sperm quality and testicular damage. Oxidative stress (OS) plays a pivotal role in the development of DM complications. Glutathione (GSH) is a part of a nonenzymatic antioxidant defense system that protects lipid, protein, and nucleic acids from oxidative damage. However, the protective effects of exogenous GSH on the male reproductive system have not been comprehensively examined. This study determined the impact of GSH supplementation in ameliorating the adverse effect of type 1 DM on sperm quality and the seminiferous tubules of diabetic C57BL/6NTac mice. GSH at the doses of 15 mg kg⁻¹ and 30 mg kg⁻¹ was given intraperitoneally to mice weekly for 6 consecutive weeks. The mice were then weighed, euthanized, and had their reproductive organs excised. The diabetic (D Group) showed significant impairment of sperm quality and testicular histology compared with the nondiabetic (ND Group). Diameters of the seminiferous lumen in diabetic mice treated with 15 mg kg⁻¹ GSH (DGSH15) were decreased compared with the D Group. Sperm motility was also significantly increased in the DGSH15 Group. Improvement in testicular morphology might be an early indication of the protective roles played by the exogenous GSH in protecting sperm quality from effects of untreated type 1 DM or diabetic complications. Further investigation using different doses and different routes of GSH is necessary to confirm this suggestion.

Momordica charantia Extract Protects against Diabetes-Related Spermatogenic Dysfunction in Male Rats: Molecular and Biochemical Study

More than 90% of diabetic patients suffer from sexual dysfunction, including diminished sperm count, sperm motility, and sperm viability, and low testosterone levels. The effects of Momordica charantia (MC) were studied by estimating the blood levels of insulin, glucose, glycosylated hemoglobin (HbA1c), testosterone (TST), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in diabetic rats treated with 250 and 500 mg/kg b.w. of the total extract. Testicular antioxidants, epididymal sperm characteristics, testicular histopathology, and lesion scoring were also investigated. Testicular mRNA expression of apoptosis-related markers such as antiapoptotic B-cell lymphoma-2 (Bcl-2) and proapoptotic Bcl-2-associated X protein (Bax) were evaluated by real-time PCR. Furthermore, caspase-3 protein expression was evaluated by immunohistochemistry. MC administration resulted in a significant reduction in blood glucose and HbA1c and marked elevation of serum levels of insulin, TST, and gonadotropins in diabetic rats. It induced a significant recovery of testicular antioxidant enzymes, improved histopathological changes of the testes, and decreased spermatogenic and Sertoli cell apoptosis. MC effectively inhibited testicular apoptosis, as evidenced by upregulation of Bcl-2 and downregulation of Bax and caspase-3. Moreover, reduction in apoptotic potential in MC-treated groups was confirmed by reduction in the Bax/Bcl-2 mRNA expression ratio.

Total flavonoids of Epimedium ameliorates testicular damage in streptozotocin-induced diabetic rats by suppressing inflammation and oxidative stress

Testicular damage is the anomaly that will often accompany diabetes mellitus. Thus, this study aimed to investigate the role that total flavonoids of Epimedium (TFE) played against streptozotocin (STZ)-induced diabetic testicular dysfunction and to elucidate the mechanism of action. The diabetic rat model was induced by vein injection of STZ in healthy rats. Thirty male healthy Spraque-Dawley rats were randomly divided into following groups: the control group, the diabetic group, and the diabetic + TFE group. Gastrointestinal administration begins at fifth week of TFE for 6 weeks. After TFE administration, all animals were euthanized. Testicular tissue samples and blood samples of rats were collected for histopathological examination and for determination of levels of various biomarkers including blood glucose, testosterone, testicular enzymes, and oxidative stress indicators. All testes were weighted to calculate the testicular organ index. Hematoxylin-eosin staining was used for observing the testis and epididymis pathological changes. Protein expression (monocyte chemoattractant protein-1, transforming growth factor-beta-1, interleukin-6, and 3-beta-hydroxysteroid dehydrogenase) was detected by immunohistochemistry and western blot techniques. There was a significant difference in the changes between the diabetes group and the control group. As a result of treat with TFE, the blood glucose decreased but there was no significant difference, and other indicators showed significant improvement. TFE may protect against STZ-induced testicular injury by suppressing inflammation and oxidative stress.

Hyperglycemia induces spermatogenic disruption via major pathways of diabetes pathogenesis

Diabetes-induced hyperglycemia has previously been shown to impact on male sub-/infertility, however, still little is known about the underlying mechanisms. In the present study we have addressed three major biochemical pathways implicated in the pathogenesis of hyperglycemia induced organ damage (the advanced glycation end product (AGE) formation pathway, the diacylglycerol-protein kinase C pathway (PKC), and the polyol pathway) in both testis and epididymis of the Ins2^Akita mouse model of Type 1 diabetes (T1DM). Hyperglycemia activated both the PKC and the polyol pathway in a significant and progressive manner within the testis, but not within the epididymis. While the AGE receptor was ubiquitiously expressed in the testis, concentrations of precursor methylglyoxal and AGE carboxymethyllysine were increased in both epididymis and testis in diabetic mice. However, AGEs did not activate intracellular pathways of ERK1, ERK2, Rela, Nrf-2, IkBkB, NFkB except CDC42, Akt1. In conclusion, two of the major pathways of hyperglycemia-induced organ damage were clearly activated within the testis of T1DM mice. This provides therapeutical opportunities in the treatment of diabetic male reproductive dysfunction.

Isolation, characterization, and therapeutic activity of bergenin from marlberry (Ardisia colorata Roxb.) leaf on diabetic testicular complications in Wistar albino rats

Bergenin is one of the phytochemical constituents in marlberry (Ardisia colorata Roxb.) having antioxidant, anti-diabetic, and anti-inflammatory properties. A. colorata has been used as an herbal medicine in Southeast Asia particularly in Northeast India to treat diabetes. Bergenin was isolated from methanol extract of A. colorata leaf (MEACL) by column chromatography and TLC profiling. Characterization and structural validation of bergenin were performed by spectroscopic analyses. A LC-ESI-MS/MS method was developed for the quantitation of bergenin and validated as per the guidelines of FDA and EMA. The validated method was successfully utilized to quantify bergenin concentration in MEACL samples. Therapeutic efficacy of bergenin was investigated on streptozotocin-induced diabetic rats by following standard protocols. Bergenin supplementation significantly improved the physiological and metabolic processes and in turn reverses diabetic testicular dysfunction via increasing serum testosterone concentrations and expression pattern of PCNA, improving histopathological and histomorphometric manifestations, modulating spermatogenic events and germ cell proliferation, restoring sperm quality, reducing sperm DNA damage, and balancing the antioxidant enzymes levels. Hence, A. colorata leaf is one of the alternate rich resources of bergenin and could be used as a therapeutic agent for diabetic testicular complications.

Chronic hyperglycemia mediated physiological alteration and metabolic distortion leads to organ dysfunction, infection, cancer progression and other pathophysiological consequences: An update on glucose toxicity

Chronic exposure of glucose rich environment creates several physiological and pathophysiological changes. There are several pathways by which hyperglycemia exacerbate its toxic effect on cells, tissues and organ systems. Hyperglycemia can induce oxidative stress, upsurge polyol pathway, activate protein kinase C (PKC), enhance hexosamine biosynthetic pathway (HBP), promote the formation of advanced glycation end-products (AGEs) and finally alters gene expressions. Prolonged hyperglycemic condition leads to severe diabetic condition by damaging the pancreatic β-cell and inducing insulin resistance. Numerous complications have been associated with diabetes, thus it has become a major health issue in the 21st century and has received serious attention. Dysregulation in the cardiovascular and reproductive systems along with nephropathy, retinopathy, neuropathy, diabetic foot ulcer may arise in the advanced stages of diabetes. High glucose level also encourages proliferation of cancer cells, development of osteoarthritis and potentiates a suitable environment for infections. This review culminates how elevated glucose level carries out its toxicity in cells, metabolic distortion along with organ dysfunction and elucidates the complications associated with chronic hyperglycemia.

Hyperglycemia induced testicular damage in type 2 diabetes mellitus rats exhibiting microcirculation impairments associated with vascular endothelial growth factor decreased via PI3K/Akt pathway

As an endocrine disease, type 2 diabetes mellitus (T2DM) can cause testicular damage which induces male infertility. However, the underlying mechanism is still not clear. We prove that T2DM induced testicular microcirculation impairment involves the decrease of VEGF and these actions are regulated by PI3K/Akt pathway. In our study, rats were divided into three groups (n=8): control group, diabetes group and diabetes + VEGF group. Intraperitoneal injection of streptozotocin (STZ, 65mg/Kg, at 9^th week) and daily high-fat diet were used to establish T2DM rat model. Serum glucose in diabetes group and diabetes + VEGF group obviously exceeded 13mmol/L after STZ injection. Immunohistochemical studies indicated that VEGF level in diabetes group significantly decreased. In diabetes group, testicular blood velocity and vascular area reduced evaluated by Doppler and FITC. Furthermore, atrophic testicular morphology and increasing apoptosis cells were evaluated by haematoxylin and eosin staining and TUNEL assay. In diabetes + VEGF group, the administration of VEGF (intraperitoneally, 10mg/kg) can significantly alleviated hyperglycemia-induced impairment of testes in above aspects. Finally, we used Western blot to analyze the mechanism of hyperglycemia-induced testicular VEGF decrease. The results indicated that hyperglycemia-induced VEGF decreased is regulated by PI3K/Akt pathway in Rats testicular sertoli cells (RTSCs). Together, we demonstrate that T2DM can reduce testicular VEGF expression, which results in testicular microcirculation impairment, and then induces testicular morphological disarrangement and functional disorder. These actions are triggered by PI3K/Akt pathway. Our findings provide solid evidence for VEGF becoming a therapeutic target in T2DM related male infertility.

Increased Indoleamine 2,3-Dioxygenase and Quinolinic Acid Expression in Microglia and Müller Cells of Diabetic Human and Rodent Retina

Purpose

We investigated the relationship between inflammation, neuronal loss, and expression of indoleamine 2, 3-dioxygenase (IDO) and quinolinic acid (QUIN) in the retina of subjects with type 1 diabetes (T1D) and type 2 diabetes (T2D) and in the retina of rats with T1D.

Methods

Retinas from T1D (n = 7), T2D (n = 13), and 20 age-matched nondiabetic human donors and from T1D (n = 3) and control rats (n = 3) were examined using immunohistochemistry for IDO, QUIN, cluster of differentiation 39 (CD39), ionized calcium-binding adaptor molecule (Iba-1, for macrophages and microglia), Vimentin (VIM; for Müller cells), neuronal nuclei (NeuN; for neurons), and UEA1 lectin (for blood vessels).

Results

Based on morphologic criteria, CD39⁺/ionized calcium binding adaptor molecule 1(Iba-1⁺) resident microglia and CD39⁻/Iba-1⁺ bone marrow–derived macrophages were present at higher density in T1D (13% increase) and T2D (26% increase) human retinas when compared with controls. The density and brightness of IDO⁺ microglia were increased in both T1D and T2D human retinas. The intensity of QUIN⁺ expression on CD39⁺ microglia and VIM⁺ Müller cells was greatly increased in both human T1D and T2D retinas. T1D retinas showed a 63% loss of NeuN⁺ neurons and T2D retinas lost approximately 43% when compared with nondiabetic human retinas. Few QUIN⁺ microglia-like cells were seen in nondiabetic retinas, but the numbers increased 18-fold in T1D and 7-fold in T2D in the central retina. In T1D rat retinas, the density of IDO⁺ microglia increased 2.8-fold and brightness increased 2.1-fold when compared with controls.

Conclusions

Our findings suggest that IDO and QUIN expression in the retinas of diabetic rats and humans could contribute to the neuronal degeneration that is characteristic of diabetic retinopathy.