Cilostazol alleviates streptozotocin-induced testicular injury in rats via PI3K/Akt pathway

Cilostazol for the treatment of distal symmetrical polyneuropathy in diabetes mellitus: Where do we stand?

INTRODUCTION

Diabetic Neuropathy (DN) is one of the most frequent chronic complications of diabetes mellitus. Its commonest form, distal symmetrical polyneuropathy (DSPN), is characterised by slowly progressing length-dependent nerve damage in the lower limbs, increasing the risk of foot ulcerations and leading to symptoms like tingling, pain, or numbness.

AIM

The aim of this review was to discuss the utility of cilostazol, a phosphodiesterase inhibitor with known antiplatelet, vasodilatory, anti-inflammation properties, in the treatment of DSPN.

RESULTS

Preclinical studies in animals have demonstrated the ability of cilostazol to improve nerve function and to protect from peripheral nerve disruption and central sensitisation. However, clinical trials in humans are very sparse and have so far not been encouraging.

CONCLUSIONS

Further research is needed to fully understand the mechanisms and potential efficacy of cilostazol in treating DSPN.

Bezafibrate alleviates diabetes-induced spermatogenesis dysfunction by inhibiting inflammation and oxidative stress

The metabolic disorders caused by diabetes can lead to various complications, including male spermatogenesis dysfunction. Exploring effective therapeutics that attenuate diabetes mellitus (DM)-induced male subfertility is of great importance. Pharmaceuticals targeting PPARα activation such as bezafibrate have been regarded as an important strategy for patients with diabetes. In this study, we use streptozocin (STZ) injection to establish a type 1 DM mice model and use bezafibrate to treat DM mice and evaluate the effects of bezafibrate on the spermatogenic function of the DM male mice. Bezafibrate treatment exhibited protective effects on DM-induced spermatogenesis deficiency, as reflected by increased testis weight, improved histological morphology of testis, elevated sperm parameters, increased serum testosterone concentration as well as increased mRNA levels of steroidogenesis enzymes. Meanwhile, testicular cell apoptosis, inflammation accumulation and oxidative stress status were also shown to be alleviated by bezafibrate compared with the DM group. In vivo and in vitro studies, PPARα specific inhibitor and PPARα knockout mice were further used to investigate the role of PPARα in the protective effects of bezafibrate on DM-induced spermatogenesis dysfunction. Our results indicated that the protection of bezafibrate on DM-induced spermatogenesis deficiency was abrogated by PPARα inhibition or deletion. Our study suggested that bezafibrate administration could ameliorate DM-induced spermatogenesis dysfunction and may represent a novel practical strategy for male infertility.

Cilostazol Stimulates Angiogenesis and Accelerates Fracture Healing in Aged Male and Female Mice by Increasing the Expression of PI3K and RUNX2

Fracture healing in the aged is associated with a reduced healing capacity, which often results in delayed healing or non-union formation. Many factors may contribute to this deterioration of bone regeneration, including a reduced 'angiogenic trauma response'. The phosphodiesterase-3 (PDE-3) inhibitor cilostazol has been shown to exert pro-angiogenic and pro-osteogenic effects in preclinical studies. Therefore, we herein analyzed in a stable closed femoral fracture model whether this compound also promotes fracture healing in aged mice. Forty-two aged CD-1 mice (age: 16-18 months) were daily treated with 30 mg/kg body weight cilostazol (n = 21) or vehicle (control, n = 21) by oral gavage. At 2 and 5 weeks after fracture, the femora were analyzed by X-ray, biomechanics, micro-computed tomography (µCT), histology, immunohistochemistry, and Western blotting. These analyses revealed a significantly increased bending stiffness at 2 weeks (2.2 ± 0.4 vs. 4.3 ± 0.7 N/mm) and an enhanced bone formation at 5 weeks (4.4 ± 0.7 vs. 9.1 ± 0.7 mm3) in cilostazol-treated mice when compared to controls. This was associated with a higher number of newly formed CD31-positive microvessels (3.3 ± 0.9 vs. 5.5 ± 0.7 microvessels/HPF) as well as an elevated expression of phosphoinositide-3-kinase (PI3K) (3.6 ± 0.8 vs. 17.4 ± 5.5-pixel intensity × 104) and runt-related transcription factor (RUNX)2 (6.4 ± 1.2 vs. 18.2 ± 2.7-pixel intensity × 104) within the callus tissue. These findings indicate that cilostazol accelerates fracture healing in aged mice by stimulating angiogenesis and the expression of PI3K and RUNX2. Hence, cilostazol may represent a promising compound to promote bone regeneration in geriatric patients.

High-fructose consumption suppresses insulin signaling pathway accompanied by activation of macrophage and apoptotic markers in rat testis

Dietary high-fructose may cause metabolic disturbances; however, its effect on the reproductive system is little understood. The insulin signaling pathway is critical in testicular development, maintenance of microcirculation and spermatogenesis. Therefore, in this study, we aimed to investigate the impact of dietary high-fructose on insulin signaling pathway as well as macrophage and apoptotic markers in testicular tissue of rats. Fructose was administered to male Wistar rats as a 20% solution in drinking water for fifteen-week. Gene expression of ir-β, irs-1, irs-2, pi3k, akt, mtor, and enos in the testicular samples was determined by real-time PCR. Protein expression of IR, IRS-1, IRS-2, PI3K, Akt, phospho-Akt (p-Akt), mTOR, eNOS, phospho-eNOS (p-eNOS), and GLUT5 was established by analysis of Western Blot. Testicular expression of occludin, CD163, CD68, caspase-8, and caspase-3 was analyzed by using immunohistochemical assay. Testicular level of fructose was measured by colorimetric method. Dietary high-fructose decreased mRNA expressions of irs-1, irs-2, pi3k, and mtor in the testicular tissue of rats. Also, this dietary intervention impaired protein expressions of IR, IRS-1, IRS-2, PI3K, p-Akt, mTOR, eNOS, and p-eNOS as well as p-Akt/Akt and p-eNOS/eNOS ratios in the testis of rats. However, a high-fructose diet increased the expression of CD163, CD68, caspase-8 and caspase-3, but decreased that of occludin, in the testicular tissue of rats. The high-fructose consumption in rats suppresses testicular insulin signaling but activates macrophages-related factors and apoptotic markers. These changes induced by dietary fructose could be related to male reproductive dysfunction.

Erythropoietin Suppresses the Hepatic Fibrosis Caused by Thioacetamide: Role of the PI3K/Akt and TLR4 Signaling Pathways

Erythropoietin (EPO) is recognized for its function in erythropoiesis; however, its potential antifibrotic effect against liver fibrosis remains unknown. This study examined whether EPO affects thioacetamide (TAA)-induced liver fibrosis by concentrating on the Toll-like receptor 4 (TLR4) cascade and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway as possible pathways. Male Wistar rats were randomized into four groups, which included: the negative control group, the TAA group (intraperitoneal; TAA 100 mg/kg three times per week for 2 weeks), and EPO-treated groups (150 and 300 IU/kg, i.p.) for 2 weeks after TAA injections. EPO attenuated hepatic fibrosis in a dosage-dependent way, as manifested by the diminution in serum alanine aminotransferase and aspartate aminotransferase activities, as well as the increase in albumin level. EPO inhibited the increase in tissue levels of tumor necrosis factors-α, interleukin-1β, transforming growth factor-β1, and TLR4 and raised tissue levels of PI3K and p-PI3K. EPO antioxidant properties were demonstrated by restoring hepatic glutathione and superoxide dismutase by preventing the accumulation of hepatic malondialdehyde. Further, EPO increased the protein expression of PI3K and Akt and decreased TLR4 protein expression. Immunohistochemically, EPO treatment altered tissue histology and downregulated mitogen-activated protein kinase protein expression. Overall, the research suggested that EPO could prevent TAA-induced hepatic fibrosis through upregulating the PI3K/Akt signaling cascade and downregulation the TLR4 downstream axis.

Mechanistic Protective Effect of Cilostazol in Cisplatin-Induced Testicular Damage via Regulation of Oxidative Stress and TNF-α/NF-κB/Caspase-3 Pathways

Despite being a potent anticancer drug, cisplatin has limited applicability due to its adverse effects, such as testicular damage. Consequently, reducing its toxicity becomes necessary. In this study, a selective phosphodiesterase-3 inhibitor, cilostazol, which is used to treat intermittent claudication, was examined for its ability to abrogate cisplatin-induced testicular toxicity. Its ameliorative effect was compared to that of two phosphodiesterase inhibitors, tadalafil and pentoxifylline. The study also focused on the possible mechanisms involved in the proposed protective effect. Cisplatin-treated rats showed a significant decrease in sperm number and motility, serum testosterone, and testicular glutathione levels, as well as a significant elevation in malondialdehyde, total nitrite levels, and the protein expression of tumor necrosis factor-alpha, nuclear factor-kappa β, and caspase-3. These outcomes were confirmed by marked testicular architecture deterioration. Contrary to this, cilostazol, in a dose-dependent manner, showed potential protection against testicular toxicity, reversed the disrupted testicular function, and improved histological alterations through rebalancing of oxidative stress, inflammation, and apoptosis. In addition, cilostazol exerted a more pronounced protective effect in comparison to tadalafil and pentoxifylline. In conclusion, cilostazol ameliorates cisplatin-induced testicular impairment through alteration of oxidative stress, inflammation, and apoptotic pathways, offering a promising treatment for cisplatin-induced testicular damage.

Telmisartan versus metformin in downregulating myostatin gene expression and enhancing insulin sensitivity in the skeletal muscles of type 2 diabetic rat model

Objective: Telmisartan is an angiotensin receptor blocker (ARB) that specifically blocks angiotensin II type-1 receptors (AT1R). Telmisartan has been proven to have antidiabetic effects via a variety of mechanisms, and it can be utilized in some diabetic patients due to its dual benefit for hypertensive patients with type 2 DM (T2DM) and when the other oral antidiabetic medications are intolerable or contraindicated. However, its precise underlying hypoglycemic mechanism is still obscure. Aim of work: We sought to establish a link between telmisartan administration and myostatin expression in skeletal muscles of T2DM rat model as a potential hypoglycemic mechanism of telmisartan. Materials and Methods: 32 male albino rats were included in the study; 8 rats served as controls (group I). T2DM was inducted in the other 24 rats, which were then randomly subdivided into 3 groups (8 in each): (group II) the Diabetic group and (groups III and IV) which were treated with either telmisartan (8 mg/kg/day) or metformin (250 mg/kg/day) respectively via oral gavage for a 4-week period. Results: Telmisartan administration resulted in a significant improvement in OGTT, HOMA-IR, glucose uptake, and muscle mass/body ratios in Telmisartan group as compared to Diabetic group (p < 0.05). Additionally, telmisartan induced a significant boost in adiponectin and IL-10 serum levels with a substantial drop in TNF-α and IL-6 levels in Telmisartan group compared to diabetic rats (p < 0.05). Moreover, telmisartan significantly boosted SOD and GSH, and decreased MDA levels in the skeletal muscles of telmisartan group. Furthermore, a significant downregulation of myostatin and upregulation of insulin receptor, IRS-1, and IRS-3 genes in the skeletal muscles of Telmisartan group were also detected. Histologically, telmisartan attenuated the morphological damage in the skeletal muscle fibers compared to diabetic rats, as evidenced by a considerable decrease in the collagen deposition area percentage and a reduction in NF-kB expression in the muscle tissues of group III. Conclusion: Telmisartan administration dramatically reduced myostatin and NF-kB expressions in skeletal muscles, which improved insulin resistance and glucose uptake in these muscles, highlighting a novel antidiabetic mechanism of telmisartan in treating T2DM.

Cilostazol novel neuroprotective mechanism against rotenone-induced Parkinson's disease in rats: Correlation between Nrf2 and HMGB1/TLR4/PI3K/Akt/mTOR signaling

Neuroinflammation induced by activation of the high mobility group box 1/ toll-like receptor 4 (HMGB1/TLR4) axis is one of the principal mechanisms involved in dopaminergic neuronal loss in Parkinson's disease (PD), and its activation exacerbates oxidative stress augmenting neurodegeneration.

AIMS

This study investigated the novel neuroprotective effect of cilostazol on rotenone-intoxicated rats focusing on the HMGB1/TLR4 axis, erythroid-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1), and phosphoinositide 3-kinase (PI3K)/Protein kinase B (Akt)/the mammalian target of rapamycin (mTOR) pathway. The aim is extended to correlate the Nrf2 expression with all assessed parameters as promising therapeutic targets for neuroprotection.

MAIN METHODS

Our experiment was designed as follows: vehicle group, cilostazol group, rotenone group (1.5 mg/kg, s.c), and the rotenone pretreated with cilostazol (50 mg/kg, p.o.) group. Eleven rotenone injections were injected day after day, while cilostazol was administered daily for 21 days.

KEY FINDINGS

Cilostazol significantly improved the neurobehavioral analysis, the histopathological examination, and dopamine levels. Moreover, the immunoreactivity of tyrosine hydroxylase (TH) in substantia nigra pars compacta (SNpc) enhanced. These effects were associated with enhancement of the antioxidant expression of Nrf2 and HO-1 by 1.01 and 1.08-fold, respectively, and repression of HMGB1/TLR4 pathway by 50.2 % and 39.3 %, respectively. Upregulation of the neuro-survival PI3K and Akt expression by 2.26 and 2.69-fold, respectively, and readjusting mTOR overexpression.

SIGNIFICANCE

Cilostazol exerts a novel neuroprotective strategy against rotenone-induced neurodegeneration via activation of Nrf2/HO-1, suppression of HMGB1/TLR4 axis, upregulation of PI3K/Akt besides mTOR inhibition that compels more investigations with different PD models to clarify its precise role.

Peripheral Nerve Denervation in Streptozotocin-Induced Diabetic Rats Is Reduced by Cilostazol

Background and Objective: Our previous study demonstrated that consistent treatment of oral cilostazol was effective in reducing levels of painful peripheral neuropathy in streptozotocin-induced type I diabetic rats. As diabetic neuropathy is characterized by hyperglycemia-induced nerve damage in the periphery, this study aims to examine the neuropathology as well as the effects of cilostazol treatments on the integrity of peripheral small nerve fibers in type I diabetic rats. Materials and Methods: A total of ninety adult male Sprague-Dawley rats were divided into the following groups: (1) naïve (control) group; (2) diabetic rats (DM) group for 8 weeks; DM rats receiving either (3) 10 mg/kg oral cilostazol (Cilo10), (4) 30 mg/kg oral cilostazol (Cilo30), or (5) 100 mg/kg oral cilostazol (Cilo100) for 6 weeks. Pain tolerance thresholds of hind paws toward thermal and mechanical stimuli were assessed. Expressions of PGP9.5, P2X3, CGRP, and TRPV-1 targeting afferent nerve fibers in hind paw skin and glial cells in the spinal dorsal horn were examined via immunohistochemistry and immunofluorescence. Results: Oral cilostazol ameliorated the symptoms of mechanical allodynia but not thermal analgesia in DM rats. Significant reductions in PGP9.5-, P2X3-, CGRP, and TRPV-1-labeled penetrating nerve fibers in the epidermal layer indicated denervation of sensory nerves in the hind paw epidermis of DM rats. Denervation significantly improved in groups that received Cilo30 and Cilo100 in a dose-dependent manner. Cilostazol administration also suppressed microglial hyperactivation and increased astrocyte expressions in spinal dorsal horns. Conclusions: Oral cilostazol ameliorated hyperglycemia-induced peripheral small nerve fiber damage in the periphery of diabetic rats and effectively mitigated diabetic neuropathic pain via a central sensitization mechanism. Our findings present cilostazol not only as an effective option for managing symptoms of neuropathy but also for deterring the development of diabetic neuropathy in the early phase of type I diabetes.

Ameliorative Effects of Peptide Phe-Leu-Ala-Pro on Acute Liver and Kidney Injury Caused by CCl4 via Attenuation of Oxidative Stress and Inflammation

Acute liver injury (ALI) and acute kidney injury (AKI) are significantly affected by the antioxidant status. In the present study, the protective effect and mechanism of the collagen peptide Phe-Leu-Ala-Pro (FLAP) in mice with ALI and AKI induced by carbon tetrachloride (CCl₄) were examined. The results showed that FLAP effectively improved the liver mass index, the renal mass index, and the histopathological morphology. FLAP treatment significantly decreased the levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea nitrogen (BUN), and creatinine (CRE) but increased the activity of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). The protein expression levels of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), p-protein kinase B (p-AKT), and p-phosphatidylinositol-3-kinase (p-PI3K) in the liver and kidneys were significantly up-regulated after FLAP treatment. FLAP down-regulated the levels of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), and nuclear factor-κ B (NF-κB) in liver and kidney tissues. Thus, FLAP may play a protective role in ALI and AKI by attenuating oxidative stress and inflammation mediated by the Nrf2/anti-response element (ARE) and PI3K/AKT/NF-κB pathways.

Preventive Effect of Collagen Peptides from Acaudina molpadioides on Acute Kidney Injury through Attenuation of Oxidative Stress and Inflammation

The protective effect of collagen peptide from Acaudina molpadioides (Amp) on acute kidney injury (AKI) in mice and its mechanism were explored. The results showed that Amp-fed could effectively improve the renal mass index and histopathological morphology. The levels of serum creatinine and urea nitrogen decreased significantly, while the antioxidant enzyme catalase (CAT) and superoxide dismutase (SOD) increased significantly in Amp-fed groups. Western blot results disclosed that Amp significantly upregulates the levels of heme oxygenase-1 (HO-1), Nrf2, p-PI3K, and p-AKT in the kidney. In addition, Amp could significantly downregulate the levels of nuclear factor NF-kappa-B (NF-κB), tumor necrosis factor α (TNF-α), inflammatory cytokines interleukin 6 (IL-6) and interleukin 1β (IL-1β). These findings provide evidence that Amp plays a protective role in AKI via attenuation of oxidative stress and inflammation mediated by PI3K/AKT/Nrf2 and PI3K/AKT/NF-κB pathways. This study laid a foundation for the application of Amp in the prevention of AKI.

Cilostazol induces angiogenesis and regulates oxidative stress in a dose-dependent manner: A chorioallantoic membrane study

Background

In this study, we aimed to investigate the effects of cilostazol on angiogenesis and oxidative stress using the chorioallantoic membrane model.

Methods

In this experimental study, the Ross 308 chick embryos were used. The negative control group (n=10) received no intervention. The positive control group (n=10) consisted of eggs treated with epidermal growth factor for inducing angiogenesis. Three cilostazol groups were designed with 10-7 (n=10), 10-6 (n=10), and 10-5 (n=10) M concentrations. Each egg was punctured on the sixth day of incubation, and drug pellets were introduced to the positive control and drug groups at the prespecified doses. Vascular development was evaluated on the eighth day of application. The total oxidant status, total antioxidant capacity, and oxidative stress index levels were determined from albumen liquids obtained with a syringe before and after drug application.

Results

Lower oxidative stress index levels were obtained from the positive control and cilostazol groups compared to the negative control albumens (p=0.001). The increments in vascular junctions and newly developed vascular nodules were evaluated in drug-free and drug-applied chorioallantoic membranes. The highest activity was obtained in the 10-7 M concentration cilostazol group. An increased angiogenic activity was detected in all drug groups in each concentration compared to the negative control group (p=0.001). Angiogenic activity was similar in all the cilostazol-treated groups (p=0.43).

Conclusion

Cilostazol has a positive stimulant effect on angiogenesis and it seems to suppress oxidative stress during embryonic growth. Cilostazol exerts these effects significantly and similarly at different doses.

Dose dependent effect of cilostazol in induced testicular ischemia reperfusion via modulation of HIF/VEGF and cAMP/SIRT1 pathways

Twisting of the spermatic cord is a common dangerous health problem that may be accompanied with testicular necrosis and infertility. Cilostazol (CLZ) is a selective phosphodiesterase (PDE) 3A inhibitor used for treatment of intermittent claudication. It has a great role in myocardial, spinal cord and hepatic ischaemia/reperfusion. However, till now, there are no researches evaluating its role in testicular ischaemia/reperfusion (TIR). The current work studies its capability to improve TIR induced injury with more concentration on the mechanisms involved in such effect. Four groups of animals were included: sham, TIR induced group, TIR plus CLZ low dose (10 mg/kg), TIR plus CLZ high dose (30 mg/kg). Our results proved that TIR had significant decrease of the serum ELISA of testosterone, marked disturbances in oxidative stress evaluated parameters as malondialdehyde (MDA), reduced glutathione (GSH), total antioxidant capacity (TAC), ELISA measurement of tumor necrosis factor alpha (TNFα) and interleukin 1 beta (IL1β) inflammatory mediators, apoptotic marker (caspase3) using western blotting, immunohistochemistry of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF). TIR reduced the protective agents as cyclic adenosine monophosphate (cAMP) and sirtuin-1 (SIRT1) by ELISA method with marked germinal cell apoptosis. The biochemical results were confirmed by the histopathological findings that showed marked decrease in both Johnsen's score and Cosentino's score. However, treatment with CLZ significantly reversed the profound TIR damaging effects, on the basis of its anti-inflammatory, anti-oxidant, and anti-apoptotic activities with recuperation of the testicular vascularity. Modulation of HIF/VEGF and cAMP/SIRT1 pathways showed a great role in mediating such effect.

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.

Momordica cymbalaria improves reproductive parameters in alloxan-induced male diabetic rats

Male reproductive dysfunction is one of the common complications of diabetes mellitus that causes infertility. This study was designed to investigate the protective effect of Momordica cymbalaria (M. cymbalaria) extracts on diabetes mediated reproductive toxicity in male Wistar rats. The induction of diabetes was performed using a single intraperitoneal injection of alloxan (120 mg/kg). Skin and seed extracts (250 and 500 mg/kg) of M. cymbalaria were orally administered to alloxan-induced diabetic male rats for 28 days. Postprandial blood glucose (PBG) levels were recorded at 7-day interval for four weeks. The effects of the treatment on blood glucose, weight of reproductive organs, sperm count, testosterone levels, antioxidant capacity, and histomorphology were evaluated. Treatment with the above extracts of M. cymbalaria significantly (p < 0.05) improved the reproductive parameters as well as the antioxidant levels superoxide dismutase (SOD) and glutathione-s-transferase (GST) in the diabetic rats. Also, oral treatment with M. cymbalaria extracts significantly reduced the PBG and malondialdehyde (MDA) levels. Further, it revived the histomorphology of reproductive organs in diabetic rats. Interestingly, skin extract at a dose of 500 mg/kg was found to be more efficient in elevating the level of testosterone and sperm count in the diabetic rats. Based on the results, it is clear that M. cymbalaria not only regulates the postprandial blood glucose levels but also improves the reproductive health in the diabetic state.

FoxO1 signaling as a therapeutic target for type 2 diabetes and obesity

Glucose production and the consumption of high levels of carbohydrate increase the chance of insulin resistance, especially in cases of obesity. Therefore, maintaining a balanced glucose homeostasis might form a strategy to prevent or cure diabetes and obesity. The activation and inhibition of glucose production is complicated due to the presence of many interfering pathways. These pathways can be viewed at the downstream level because they activate certain transcription factors, which include the Forkhead-O1 (FoxO1). This has been identified as a significant agent in the pancreas, liver, and adipose tissue, which is significant in the regulation of lipids and glucose. The objective of this review is to discuss the intersecting portrayal of FoxO1 and its parallel cross-talk which highlights obesity-induced insulin susceptibility in the discovery of a targeted remedy. The review also analyses current progress and provides a blueprint on therapeutics, small molecules, and extracts/phytochemicals which are explored at the pre-clinical level.

Clusterin suppresses spermatogenic cell apoptosis to alleviate diabetes-induced testicular damage by inhibiting autophagy via the PI3K/AKT/mTOR axis

BACKGROUND INFORMATION

Diabetes-induced testicular dysfunction is characterised by abnormal apoptosis of spermatogenic cells, but the underlying mechanism is poorly understood. This study aimed to investigate the roles of clusterin (CLU) in testicular damage associated with diabetes pathogenesis, as well as the molecular mechanism. A rat diabetes model was established using streptozocin, and the mouse spermatogenic cell line GC-1 spg was treated with high glucose as a cellular model. CLU was overexpressed in GC-1 spg cells, followed by detection of serum testosterone, cell proliferation, cell apoptosis and autophagy.

RESULTS

CLU expression was significantly reduced and LC3 expression was elevated in testis tissues in the rat diabetes model and high glucose-treated GC-1 spg cells. High glucose led to suppressed viability, enhanced apoptosis, reduced Bcl-2 expression, elevated Bax expression and cleavage of Caspase-3/-9 in GC-1 spg cells, and these effects were abrogated by CLU overexpression. Additionally, CLU overexpression repressed LC3 and Beclin-1 expression, reduced the LC3II/LC3I ratio and promoted p62 expression in GC-1 spg cells in the presence of high glucose, and these effects were all mitigated by rapamycin treatment. Inhibition of PI3K/AKT/mTOR signalling with LY294002 activated autophagy in CLU-overexpressing GC-1 spg cells under high glucose conditions. CLU overexpression repressed autophagy and alleviated testicular damage in diabetic rats, which was also abrogated by LY294002 treatment.

CONCLUSIONS

CLU expression is suppressed during diabetes-induced testicular damage, whereas CLU overexpression alleviates diabetes-induced testicular damage by activating PI3K/AKT/mTOR signalling to inhibit autophagy and further repress spermatogenic cell apoptosis.

Diabetes mellitus and the impairment of male reproductive function: Possible signaling pathways

BACKGROUND AND AIMS

Today, it has been shown that diabetes mellitus (DM) can affect male fertility. Glucose metabolism is a vital process in spermatogenesis that is impacted by diabetes condition. But the mechanisms by which DM causes male infertility are not wholly clarified. The aim of this review is to provide brief information about the influence of hyperglycemia on male fertility and specific emphasis on the molecular signaling pathway that is involved.

METHODS

Broad literature search in the electronic database "Pubmed", "Google Scholar", the website of "World Health Organization" (WHO) and Control Disease and Prevention (CDC) took place. There was no time restriction. A key criterion for the selection of articles was English and language. Finally, one hundred thirty seven articles were included in the review.

RESULTS

Diabetes mellitus affects many signaling pathways that involved in the spermatogenesis. It seems that increased ROS and oxidative stress in the diabetes is the beginning of all fertility problems and affects all of involved signaling pathways in the spermatogenesis.

CONCLUSIONS

It seems that there was strong interconnected between oxidative stress and all of involved signaling pathways in the reproductive problems in diabetes. So, approaches that diminish oxidative stress in the testis can be effective in improving diabetes related infertility complications.

Cilostazol protects against cyclophosphamide-induced ovarian toxicity in female rats: role of cAMP and HO-1

Purpose: Cancer rates have been increased among women of reproductive age nowadays. Hence, many young female will be exposed to chemotherapeutic agents as cyclophosphamide (CP), carrying the hazards on female fertility. Cilostazol is a selective phosphodiesterase-3 inhibitor drug which exhibits antioxidant, anti-inflammatory, and anti-apoptotic activities. We aimed in this study to explore the possible protective effects of cilostazol against CP-induced ovarian damage in female rats.Methods: Cilostazol (10 mg/kg/day) was administered orally for 10 days in presence and absence of CP (150 mg/kg IP single dose) treatment. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen (E2), and anti-Müllerian hormone (AMH) levels were determined. Ovarian oxidative stress parameters along with inflammatory biomarkers were measured. 3,5-Cyclic adenosine monophosphate (cAMP) ovarian level was detected. Ovarian histopathological examination and caspase-3 immunohistochemical study were evaluated.Results: CP-treated rats showed a significant increase in serum levels of FSH and LH with decreased serum E2 and AMH levels with an increase in the ovarian inflammatory and oxidative stress biomarkers besides a significant decrease in cAMP ovarian level with an evident histopathological picture of ovarian damage and a high caspase-3 immunoexpression. Cilostazol pretreatment significantly restored the distributed hormonal levels, the oxidative stress and inflammatory biomarkers to their normal levels with marked improvement in histopathological picture of ovarian damage with a significant decrease in caspase-3 immunoexpression.Conclusions: These data suggest that cilostazol protects against CP- induced ovarian damage, which may be related to an increase in cAMP with subsequent anti-inflammatory, antioxidant, and anti-apoptotic properties.

Fenofibrate ameliorates testicular damage in rats with streptozotocin-induced type 1 diabetes: role of HO-1 and p38 MAPK

BACKGROUND

Since diabetes mellitus type-1 (DM-1) induces testicular oxidative and inflammatory damage with finally an ultimate male infertility, and as fenofibrate (FEN) plays an important antioxidant and anti-inflammatory role, the aim of the present study was to investigate the effects of FEN on diabetes-induced reproductive damage and clarifying the underlying related mechanisms.

METHODS

DM-1 was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin (50 mg/kg). FEN (100 mg/kg/day, orally) was administrated to diabetic rats for 4 weeks. Testicular damage was detected by estimation of both testicular and body weights, assessment of serum testosterone, testicular oxidative stress parameters (malondialdehyde and nitric oxide levels) and testicular oxidant defenses (reduced glutathione, superoxide dismutase and hemeoxygenase-1). Expressions of the inflammatory markers (inducible nitric oxide synthase, p38 mitogen-activated protein kinase (MAPK), tumor necrosis factor alpha, interleukin-6 and apoptotic marker (caspase-3) were evaluated in testicular tissue. Our results were confirmed by histopathological examination of testicular tissues.

RESULTS

Diabetic testicular damage was proved by both biochemical and histopathological examinations. FEN treatment reversed diabetic testicular damage; normalized the serum testosterone level, improved anti-oxidative capacity, ameliorated the pro-inflammatory cytokine expression in testicular tissue with the down regulation of p38 MAPK mediated-testicular apoptosis.

CONCLUSION

FEN treatment exerted a protective effect against streptozotocin-induced diabetic reproductive dysfunction not only through its powerful antioxidant and hypoglycemic effects, but also through its anti-inflammatory and anti-apoptotic effect via down-regulation of testicular p38 MAPK expression in diabetic rats.

Possible mechanisms mediating the protective effect of cilostazol in L-arginine induced acute pancreatitis in rats: role of cGMP, cAMP, and HO-1

Acute pancreatitis (AP) is an inflammatory disorder with a high mortality rate. Cilostazol is a selective phosphodiesterase-3 inhibitor drug that is commonly used as an antiplatelet, antithrombotic, and vasodilator drug. It exhibits antioxidant, anti-inflammatory, and anti-apoptotic activities, but its effect on AP has not been fully elucidated yet. The present study aimed to investigate the effects of cilostazol on L-arginine-induced AP and the possible protective mechanisms. A rat model of AP was established by a single i.p. injection of 3-g/kg L-arginine on day 13 of the experiment. The treated groups received a single daily oral dose of either 100 or 300 mg/kg/day for 14 consecutive days. Rats with AP showed histopathological changes of pancreatic tissue injury together with increased serum amylase enzyme activity and decreased serum insulin, pancreatic adiponectin, and cGMP levels. Moreover, AP rats showed increased pancreatic inflammatory biomarker (TNF-α, VCAM-1, and MPO) levels with decreased anti-inflammatory IL-10 levels. In addition, oxidative stress biomarkers (MDA and NO) were increased in AP with decreased antioxidant SOD activity and GSH level. Moreover, HO-1 immunostaining was increased in the AP group. Cilostazol pretreatment reversed the histopathological change; decreased the amylase activity and the levels of TNF-α, VCAM-1, and MPO; and increased the levels of insulin, adiponectin, cGMP, cAMP, and IL-10. Moreover, cilostazol decreased MDA and NO but increased SOD and GSH. Lastly, cilostazol increased the HO-1 immunostaining more than in the AP group. These data suggest that cilostazol protects against L-arginine-induced AP, which may be related to an increase in cGMP, cAMP, and upregulation of HO-1 with subsequent anti-inflammatory and antioxidant properties.

Role of Nrf2/HO-1 and PI3K/Akt Genes in the Hepatoprotective Effect of Cilostazol

BACKGROUND

Cilostazol, a phosphodiesterase 3 inhibitor (PDE3I), is a platelet aggregation inhibitor and vasodilator that is useful for treating intermittent claudication. Experimental studies have shown that cilostazol has potent anti-inflammatory, anti-oxidant effects effects.

OBJECTIVES

Although the hepatoprotective effect cilostazol has been studied, the molecular mechanisms of such protection, including: the nuclear factor-erythroid 2-related factor 2 (Nrf2) / hemoxygenase (HO-1) and the phosphoinositide 3-kinase (PI3K) /serine/threonine kinase (Akt) pathways are not fully explored, which is the aim of this study.

METHODS

To achieve the aim of this study, 35 rats were grouped into: control groups, liver injury group (model- non treated: injected with thioacetamide (TAA), 150 mg/kg, i.p.), and two cilostazoltreated groups (treated with cilostazol 10 and 50 mg/kg, p.o.). The rats were treated for 8 days and injected with TAA on the 7th day of the experiment and sacrificed 48 hours after TAA injection.

RESULTS

The model group showed evidence of liver injury as indicated by the elevation of liver enzymes and confirmed by histopathological findings. TAA-induced liver injury was accompanied by down-regulation of the cytoprotective pathways: PI3K/Akt and Nrf2/HO-1 mRNAs. Cilostazol administration ameliorated TAA-induced liver injury, where it caused a significant improvement in the activity of liver enzymes as well as in the histopathological changes. Such an effect was associated with a significant increase in the expression of PI3K/Akt and Nrf2/HO-1 mRNAs as detected by Real-time reverse transcription polymerase chain reaction (RT-PCR).

CONCLUSION

Cilostazol protected rats against TAA hepatotoxicity through up-regulation of PI3K/Akt and Nrf2/HO-1 gene expression.

PTEN/PI3K/VEGF signaling pathway involved in the protective effect of xanthine oxidase inhibitor febuxostat against endometrial hyperplasia in rats

Endometrial hyperplasia (EH) is a medical condition that affects many females as it increases their uterine carcinogenic potential. EH results from entangling hormonal imbalance and inflammatory response. The study examined the role of a xanthine oxidase inhibitor, febuxostat, in a rat model of EH. Adult female Wistar albino rats were subjected to estradiol valerate (EV) 2 mg/kg for 10 days to induce EH. Another group was treated concomitantly with febuxostat 10 mg/kg for the same period. The uterine malondialdehyde, reduced glutathione (GSH), and superoxide dismutase (SOD) were assessed by chemical methods. Gene expressions of phosphatidylinositol-3-kinase (PI3K), Akt, and hypoxia-inducible factor 1 alpha were assessed by the quantitative real-time polymerase chain reaction. Moreover, the vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay. Histopathology and immunohistochemical techniques were used for the detection of phosphatase and tensin homolog (PTEN). The results revealed that EV administration induced complex EH with focal atypia and loss of PTEN expression by the histological examination. Uteri of the EV group showed a significant drop in GSH content and SOD activity and rise in the expressions of PI3K, Akt, VEGF, and IL-6. Febuxostat administration significantly improved the uterine GSH and SOD levels. It decreased the expressions of PI3K, Akt, VEGF, and IL-6. The endometrium showed a regression of the proliferative epithelium with the restoration of PTEN expression and the absence of the atypical features. In conclusion, febuxostat protected the endometrium against estrogen-induced EH and may be beneficial in the management along with the hormonal therapy.

Rupatadine, a dual antagonist of histamine and platelet-activating factor (PAF), attenuates experimentally induced diabetic nephropathy in rats

The role of histamine and platelet activating factor (PAF) as involved mediators in the pathophysiology of diabetic complications, in particular diabetic nephropathy (DN), has become a new focus of concern. Accordingly, the present study designed to explore the effect of rupatadine (RUP), a dual antagonist of histamine (H1) and PAF, on the progression of experimentally induced DN in rats. Rats were divided into five groups: control, RUP alone, streptozotocin (STZ)-diabetic model, STZ/RUP (3 mg/kg/day), and STZ/RUP (6 mg/kg/day). Treatment has continued for 4 weeks after diabetes confirmation. At the end of the study, serum was collected for measurement of glucose, insulin, urea, creatinine, histamine, and PAF. Renal tissue homogenates were prepared for measuring oxidative stress indices, tumor necrosis factor (TNF-α), cystatin C, and p21. Moreover, immunohistochemical expression of transforming growth factor-β1 (TGF-β1) and p53 along with histological pictures was also conducted. Antagonizing H1 and PAF receptors by RUP ameliorated the experimentally induced DN as evident by decreasing all serum parameters augmented by STZ together with improvement of the histopathological picture. RUP administration also improved oxidative-antioxidative agents with reduction in the anti-inflammatory marker, TNF-α. Additionally, the immunohistochemical expression of the fibrosis marker; TGF-β1, was also decreased. STZ-induced DN showed a p21/p53-dependent induction of premature senescence and RUP administration decreased the expression of p21 and p53 levels in injured renal tissue. RUP represents a novel promising drug to prevent DN complicated diabetes probably via its inhibitory effect on H1 and PAF receptors. The renal protection was also related to the anti-inflammatory and antioxidant roles and PAF-facilitated senescence effect via p21/p53 signaling.

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.

Protective effects of Salidroside on spermatogenesis in streptozotocin induced type-1 diabetic male mice by inhibiting oxidative stress mediated blood-testis barrier damage

Spermatogenic dysfunction is one of the major secondary complications of male diabetes. Salidroside (SAL) is the important active ingredients isolated from Herba Cistanche, which exhibits numerous pharmacological activities such as antioxidant, anti-diabetic, and anti-inflammatory effects. The present study was designed to determine whether SAL contributes to the recovery from spermatogenic dysfunction in streptozotocin (STZ) induced type-1 diabetic mice. SAL (25, 50, or 100 mg/kg) and Clomiphene citrate (CC, 5 mg/kg) were orally administered to male type-1 diabetic mice for 10 weeks. Testis tissues were collected for histopathological and biochemical analysis. Moreover, reproductive organ weight, sperm parameters, and testicular cell DNA damage were estimated. The results revealed that SAL significantly improved the weight of the reproductive organs, sperm parameters and testicular morphology to different degrees in type-1 diabetic mice. Furthermore, reactive oxygen species (ROS) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), markedly increased in the testicular tissue after SAL treatment. In addition, our data also showed a marked downregulation the fluorescence expressions of p38 MAPK phosphorylation and upregulation the protein expressions of ZO-1, Occludin, Claudin-11 and N-cadherin after SAL administration (100 mg/kg) compared with the type-1 diabetic group. In conclusion, these results demonstrated that SAL exerts protective effects on type-1 diabetes-induced male spermatogenic dysfunction, which is likely mediated by inhibiting oxidative stress-mediated blood testis barrier damage.

Benzo[a]pyrene induces pyroptotic and autophagic death through inhibiting PI3K/Akt signaling pathway in HL-7702 human normal liver cells

Benzo(α)pyrene (BaP) possesses a forceful hepatotoxicity, and is ubiquitous in foods and ambient air. Our previous study found that BaP induced pyroptotic and autophagic death in HL-7702 human liver cells; the relevant mechanisms, however, remain unknown. This work was therefore to unravel the effects of the PI3K/Akt signaling pathway on pyroptotic and autophagic death triggered by BaP. Cells were treated with or without LY294002 (PI3K/Akt inhibitor) and IGF-1 (PI3K/Akt activator) before BaP exposure, and the results showed that compared with the control, the protein expression of p-Akt was markedly decreased by BaP (p < 0.05). IGF-1 did not subvert this inhibitive effect of BaP, while LY294002 enhanced it. Furthermore, the protein expression of pyroptosis (Cleaved Caspase-1, NO, IL-1β, IL-18), as well as LDH and the relative electrical conductivity were significantly augmented by BaP. The levels of these indices were increased by LY294002 pretreatment, and decreased by IGF-1. Similarly, LY294002 enhanced BaP-induced increase in the key protein expression of autophagy (Beclin-1 and LC3II), while IGF-1 weakened it. Finally, the phosphorylation of FOXO4 was clearly (p < 0.01) inhibited by BaP, and LY294002 suppressed this inhibitive effect of BaP, while IGF-1 strengthened it. In conclusion, BaP was able to induce pyroptotic and autophagic death via blocking the PI3K/Akt signaling pathway in HL-7702 liver cells.

PI3K/Akt and Nrf2/HO-1 pathways involved in the hepatoprotective effect of verapamil against thioacetamide toxicity in rats

Liver is a precious organ to maintain body life. Hepatotoxicity is a worldwide health problem that is still a challenge for research. Although countless pharmaceutical drugs and herbal compounds were screened for their hepatoprotective effects, the death from hepatotoxicity is increasing. Thus, there is continuous necessity of searching for the hepatoprotective effect of commonly used drugs. Accordingly, our aim was to examine a hepatoprotective potential for the antihypertensive drug, verapamil, and searching for new insights underlie its protective mechanism. Four groups of adult male rats were randomly arranged as controls, thioacetamide (TAA) hepatotoxic, and TAA + verapamil treated. Serum liver enzyme, hepatic antioxidant, lipid peroxidation, and inflammatory parameters were assessed. Gene relative expression for heme oxygenase-1 (HO-1), nuclear factor-erythroid 2-related factor 2 (Nrf2), phosphoinositide 3-kinase (PI3K), and serine/threonine-specific protein kinase (Akt) were quantified in hepatic tissue. TAA caused hepatic injury evident both histopathologically and biochemically by a decrease in all gene expressions. Verapamil alleviated the injury via its antioxidant and anti-inflammatory effects that were suggested to be via upregulation of the previous gene expressions. In conclusion, the calcium channel blocker, verapamil, that is used widely as antihypertensive exhibits a valuable hepatoprotective effect. The protection partially rests on activation of Nrf2/HO-1 and PI3K/Akt pathways.

Protective effects of Astragalin on spermatogenesis in streptozotocin-induced diabetes in male mice by improving antioxidant activity and inhibiting inflammation

Spermatogenic dysfunction is a common complication in men with diabetes and is the most important manifestation of diabetes-related male reproduction damage. Astragalin (AG) is one of the main flavonoids from Cuscuta chinensis, which has rich pharmacological activities. This study aimed to establish whether AG may contribute to the recovery from spermatogenic dysfunction. AG (3.3, 10 and 30 mg/kg) and Clomiphene (5 mg/kg) were orally administered to streptozotocin-induced diabetic male mice for 8 weeks. After the experiments performed, reproductive organs, sperm parameters and histomorphological changes were analysed. Antioxidant and anti-inflammatory capacity were estimated in testicular tissues. The results revealed that AG significantly improved the reproductive organs, sperm parameters and testicular morphology to different degrees in diabetic mice. Nitric oxide (NO) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), markedly increased in the testicular tissue after AG was administered. Interestingly, AG also downregulated the protein expressions of tumour necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) in testes. In conclusion, AG is a potential beneficial agent to protect diabetic-induced spermatogenic dysfunction in male mice by increasing antioxidant enzymes activities and inhibiting inflammation.

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.

A new hypoglycemic mechanism of catalpol revealed by enhancing MyoD/MyoG-mediated myogenesis

AIMS

Enhancing myogenesis has been identified as a possible target to improve insulin sensitivity and protect against metabolic diseases. Catalpol, an iridoid glycoside, has been shown to exert a hypoglycaemic effect by improvement of insulin sensitivity; however, the underlying mechanism remains unknown. In this study, we tested whether catalpol has the potential to improve insulin sensitivity by augmenting myogenesis.

MAIN METHODS

We examined the hypoglycaemic mechanism of catalpol in db/db mice and C2C12 cells. db/db mice were treated with catalpol (200 mg/kg) for 8 consecutive weeks. Serum analysis, skeletal muscle performance and histology, and gene and protein expression were performed. In vitro glucose uptake, gene and protein expression were determined, and small interfering RNA was used to identify the underlying hypoglycaemic mechanism of catalpol.

KEY FINDINGS

In this study, we tested whether catalpol has the potential to improve skeletal insulin sensitivity by augmenting myogenesis, in which we found that, catalpol treatment in db/db mice lowered blood glucose and improved insulin sensitivity via activation of phosphatidylinositol‑3‑Kinase (PI3K)/protein kinase B (AKT) pathway. Moreover, catalpol-treated mice exhibited enhanced myogenesis, as evidenced by increased myogenic differentiation (MyoD), myogenin (MyoG) and myosin heavy chain (MHC) expressions. The in vitro experimental results showed that both catalpol and metformin enhanced glucose uptake via activation of PI3K/AKT pathway. However, unlike metformin, the PI3K/AKT pathway activation by catalpol was dependent on enhanced MyoD/MyoG-mediated myogenesis.

SIGNIFICANCE

Improvement of insulin sensitivity by enhancing MyoD/MyoG-mediated myogenesis may constitute a new therapeutic approach for treating type 2 diabetes.