The mechanisms of alloxan- and streptozotocin-induced diabetes

Jinmaitong alleviates diabetic neuropathic pain by inhibiting JAK2/STAT3 signaling in microglia of diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Jinmaitong (JMT) is a prescription of Traditional Chinese Medicine that is composed of 12 crude drugs. It has been used in the treatment of diabetic neuropathic pain (DNP) for more than 30 years.

AIM OF STUDY

Microglia are thought to play an important role in neuropathic pain. This study aimed to evaluate the protective effect of JMT against DNP and to investigate the underlying mechanisms in which the microglia and JAK2/STAT3 signaling pathway were mainly involved.

MATERIALS AND METHODS

The chemical composition of JMT was analyzed using liquid chromatography tandem mass spectrometry. The diabetes model was constructed using 11 to 12-week-old male Zucker diabetic fatty (ZDF) rat (fa/fa). The model rats were divided into 5 groups and were given JMT at three dosages (11.6, 23.2, and 46.4 g/kg, respectively, calculated as the crude drug materials), JAK inhibitor AG490 (positive drug, 10 μg/day), and placebo (deionized water), respectively, for eight weeks (n = 6). Meanwhile, Zucker lean controls (fa/+) were given a placebo (n = 6). Body weight was tested weekly and blood glucose was monitored every 2 weeks. The mechanical allodynia and heat hyperalgesia were assessed using mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests. After treatment, the microglia activation marker Iba-1, CD11B, CD68, neuroinflammatory mediators, and mediators of the JAK2/STAT3 signaling pathway were compared between different groups. The mRNA and protein levels of target genes were assessed by quantitative real-time PCR and Western Blot, respectively.

RESULTS

We found that JMT significantly inhibited the overactivation of microglia in spinal cords, and suppressed neuroinflammation of DNP model rats, thereby ameliorating neurological dysfunction and injuries. Furthermore, these effects of JMT could be attributed to the inhibition of the JAK2/STAT3 signaling pathway.

CONCLUSIONS

Our findings suggested that JMT effectively ameliorated DNP by modulating microglia activation via inhibition of the JAK2/STAT3 signaling pathway. The present study provided a basis for further research on the therapeutic strategies of DNP.

Morphological evidence for the potential protective effects of curcumin and Garcinia kola against diabetes in the rat hippocampus

This research investigated the effects of sciatic nerve transection and diabetes on the hippocampus, and the protective effects of Garcinia kola and curcumin. Thirty-five adults male Wistar albino rats were divided into five groups: a control group (Cont), a transected group (Sham group), a transected + diabetes mellitus group (DM), a transected + diabetes mellitus + Garcinia kola group (DM + GK), and a transected + DM + curcumin group (DM + Cur), each containing seven animals. The experimental diabetes model was created with the intraperitoneal injection of a single dose of streptozotocin. No procedure was applied to the Cont group, while sciatic nerve transection was performed on the other groups. Garcinia kola was administered to the rats in DM + GK, and curcumin to those in DM + Cur. Cardiac perfusion was performed at the end of the experimental period. Brain tissues were dissected for stereological, histopathological, and immunohistochemical evaluations. The volume ratios of hippocampal layers to the entire hippocampus volume were compared between the groups. Anti-S100, anti-caspase 3, and anti-SOX 2 antibodies were used for immunohistochemical analysis. No statistically significant difference was observed in the volume ratios of the four hippocampal layers. However, the volume ratio of the stratum lucidum was higher in the Sham, DM, and DM + Cur groups compared to the Cont group. While curcumin exhibited a protective effect on hippocampal tissue following diabetes induction, Garcinia kola had only a weak protective effect. Increased cell density and nuclear deterioration due to diabetes and nerve transection can be partially ameliorated by treatment with Garcinia kola and curcumin.

Associations between diabetes mellitus and sensorineural hearing loss from humans and animal studies

There is controversy regarding the association and etiopathogenesis of diabetes mellitus (DM) and sensorineural hearing loss (SNHL). Some studies support that SNHL develops because of angiopathy and/or neuropathy caused by DM, but many of the findings have been inconsistent. This review aims to highlight a select number of studies that effectively describe the relationship between DM and SNHL, thus bringing more attention and awareness to this area of research. This review also describes animal models to understand better the mechanisms of DM contributing to SNHL in the inner ear. The goal of this narrative review is for researchers and healthcare professionals to further their understanding and investigation of the etiopathogenesis of both DM and SNHL, therefore leading to the development of effective treatments for diabetic patients displaying symptoms of SNHL.

A Nano-Aggregatable Acedan Derivative for Clathrin-Mediated Cellular Uptake and Two-Photon Imaging of Diabetes-Associated Lipid Droplets

Lipid droplets (LDs), the essential cytosolic fat storage organelles, have emerged as pivotal regulators of cellular metabolism and are implicated in various diseases. The noninvasive monitoring of LDs necessitates fluorescent probes with precise organelle selectivity and biocompatibility. Addressing this need, we have engineered a probe by strategically modifying the structure of a conventional two-photon-absorbing dipolar dye, acedan. This innovative approach induces nanoaggregate formation in aqueous environments, leading to aggregation-induced fluorescence quenching. Upon cellular uptake via clathrin-mediated endocytosis, the probe selectively illuminates within LDs through a disassembly process, effectively distinguishing LDs from the cytosol with exceptional specificity. This breakthrough enables the high-fidelity imaging of LDs in both cellular and tissue environments. In a pioneering investigation, we probed LDs in a diabetes model induced by streptozotocin, unveiling significantly heightened LD accumulation in cardiac tissues compared to other organs, as evidenced by TP imaging. Furthermore, our exploration of a lipopolysaccharide-mediated cardiomyopathy model revealed an LD accumulation during heart injury. Thus, our developed probe holds immense potential for elucidating LD-associated diseases and advancing related research endeavors.

Hyperglycemia influences the cell proliferation and death of the rat endocrine pancreas in the neonatal period

AIMS

To evaluate the cell proliferation and death, and structural morphology of the pancreatic islet cells of the rats with hyperglycemia in the first month of life and compare to those of the control rats.

MAIN METHODS

Female Sprague-Dawley newborn rats received Streptozotocin (a beta-cytotoxic drug) at birth for diabetes induction. Control and hyperglycemic animals were euthanized on different days of life: 5, 10, 15, and 30. The pancreas was collected and processed for immunohistochemical analysis of cleaved Caspase-3 (cell death), Ki-67 (cell proliferation), PDX-1 (transcription factor responsible for insulin synthesis), and endocrine hormones (insulin, glucagon, and somatostatin).

KEY FINDINGS

Control females showed a higher percentage (%) of Ki-67-positive(+) cells on D10 and D15, a higher % of insulin+ and somatostatin+ cells on D15 and D30, a lower % of PDX-1+ cells on D10, and a higher % of glucagon+ cells on D10 and D30. Hyperglycemic females showed a lower % of Ki-67+ cells on D15, a higher % of cleaved Caspase-3+ cells on D15, and insulin+ cells on D15 and D30. In the comparison among the experimental groups, the hyperglycemic females showed an increased % of cleaved Caspase-3+ and Ki-67+ cells and a lower % of PDX-1+ cells.

SIGNIFICANCE

This study enabled a better understanding of the abnormal pancreas development regarding cellular proliferation, apoptosis, and hormonal synthesis in the neonatal period. Thus, the pancreatic islets of hyperglycemic rats do not reestablish the normal endocrine cell population, and cellular apoptosis overcame the proliferative activity of these cells.

Exploring dose-response variability and relative severity assessment in STZ-induced diabetes male NSG mice

NSG mice are among the most immunodeficient mouse model being used in various scientific branches. In diabetelogical research diabetic NSG mice are an important asset as a xenotransplantation model for human pancreatic islets or pluripotent stem cell-derived islets. The treatment with the beta cell toxin streptozotocin is the standard procedure for triggering a chemically induced diabetes. Surprisingly, little data has been published about the reproducibility, stress and animal suffering in these NSG mice during diabetes induction. The 3R rules, however, are a constant reminder that existing methods can be further refined to minimize suffering. In this pilot study the dose-response relationship of STZ in male NSG mice was investigated and additionally animal suffering was charted by applying the novel 'Relative Severity Assessment' algorithm. By this we successfully explored an STZ dose that reliably induced diabetes while reduced stress and pain to the animals to a minimum using evidence-based and objective parameters rather than criteria that might be influenced by human bias.

Chrysin-loaded PEGylated liposomes protect against alloxan-induced diabetic neuropathy in rats: the interplay between endoplasmic reticulum stress and autophagy

BACKGROUND

Diabetic neuropathy (DN) is recognized as a significant complication arising from diabetes mellitus (DM). Pathogenesis of DN is accelerated by endoplasmic reticulum (ER) stress, which inhibits autophagy and contributes to disease progression. Autophagy is a highly conserved mechanism crucial in mitigating cell death induced by ER stress. Chrysin, a naturally occurring flavonoid, can be found abundantly in honey, propolis, and various plant extracts. Despite possessing advantageous attributes such as being an antioxidant, anti-allergic, anti-inflammatory, anti-fibrotic, and anticancer agent, chrysin exhibits limited bioavailability. The current study aimed to produce a more bioavailable form of chrysin and discover how administering chrysin could alter the neuropathy induced by Alloxan in male rats.

METHODS

Chrysin was formulated using PEGylated liposomes to boost its bioavailability and formulation. Chrysin PEGylated liposomes (Chr-PLs) were characterized for particle size diameter, zeta potential, polydispersity index, transmission electron microscopy, and in vitro drug release. Rats were divided into four groups: control, Alloxan, metformin, and Chr-PLs. In order to determine Chr- PLs' antidiabetic activity and, by extension, its capacity to ameliorate DN, several experiments were carried out. These included measuring acetylcholinesterase, fasting blood glucose, insulin, genes dependent on autophagy or stress in the endoplasmic reticulum, and histopathological analysis.

RESULTS

According to the results, the prepared Chr-PLs exhibited an average particle size of approximately 134 nm. They displayed even distribution of particle sizes. The maximum entrapment efficiency of 90.48 ± 7.75% was achieved. Chr-PLs effectively decreased blood glucose levels by 67.7% and elevated serum acetylcholinesterase levels by 40% compared to diabetic rats. Additionally, Chr-PLs suppressed the expression of ER stress-related genes (ATF-6, CHOP, XBP-1, BiP, JNK, PI3K, Akt, and mTOR by 33%, 39.5%, 32.2%, 44.4%, 40.4%, 39.2%, 39%, and 35.9%, respectively). They also upregulated the miR-301a-5p expression levels by 513% and downregulated miR-301a-5p expression levels by 65%. They also boosted the expression of autophagic markers (AMPK, ULK1, Beclin 1, and LC3-II by 90.3%, 181%, 109%, and 78%, respectively) in the sciatic nerve. The histopathological analysis also showed that Chr-PLs inhibited sciatic nerve degeneration.

CONCLUSION

The findings suggest that Chr-PLs may be helpful in the protection against DN via regulation of ER stress and autophagy.

Regulation of Oxidative Stress and Apoptosis in Streptozotocin-Induced Diabetic Rats by Egyptian Sidr Honey

Diabetes mellitus is a global health issue characterized by hyperglycemia which leads over time to severe damage to numerous tissues. The present study aimed to estimate the effect of Egyptian Sidr honey against streptozotocin (STZ)-induced diabetes in rats. Diabetic rats were treated with Sidr honey daily for 4 consecutive weeks. The biochemical profile of blood samples was measured. Furthermore, the activity of antioxidant enzymes, nitric oxide (NO), and malonaldehyde (MDA) were examined in hepatic and pancreatic tissues. Moreover, the expression of Bax, Caspase-3, and Bcl2 proteins were measured. Results revealed that the capability of Sidr honey to decline the elevated blood glucose and fructosamine levels. Also, the honey decreased the levels of NO and MDA. Furthermore, it regulated the antioxidant enzymes activity. Moreover, it reduced the expression levels of Caspase-3 and Bax while increased the Bcl2 level. In conclusion, Sidr honey can regulate hyperglycemia, oxidative stress, apoptosis, and antioxidant enzymes in STZ-induced diabetic rats.

Evaluating the Antihyperalgesic Potential of Sildenafil-Metformin Combination and Its Impact on Biochemical Markers in Alloxan-Induced Diabetic Neuropathy in Rats

(1) Background: Globally, about 600 million people are afflicted with diabetes, and one of its most prevalent complications is neuropathy, a debilitating condition. At the present time, the exploration of novel therapies for alleviating diabetic-neuropathy-associated pain is genuinely captivating, considering that current therapeutic options are characterized by poor efficacy and significant risk of side effects. In the current research, we evaluated the antihyperalgesic effect the sildenafil (phosphodiesterase-5 inhibitor)-metformin (antihyperglycemic agent) combination and its impact on biochemical markers in alloxan-induced diabetic neuropathy in rats. (2) Methods: This study involved a cohort of 70 diabetic rats and 10 non-diabetic rats. Diabetic neuropathy was induced by a single dose of 130 mg/kg alloxan. The rats were submitted to thermal stimulus test using a hot-cold plate and to tactile stimulus test using von Frey filaments. Moreover, at the end of the experiment, the animals were sacrificed and their brains and livers were collected to investigate the impact of this combination on TNF-α, IL-6, nitrites and thiols levels. (3) Results: The results demonstrated that all sildenafil-metformin combinations decreased the pain sensitivity in the von Frey test, hot plate test and cold plate test. Furthermore, alterations in nitrites and thiols concentrations and pro-inflammatory cytokines (specifically TNF-α and IL-6) were noted following a 15-day regimen of various sildenafil-metformin combinations. (4) Conclusions: The combination of sildenafil and metformin has a synergistic effect on alleviating pain in alloxan-induced diabetic neuropathy rats. Additionally, the combination effectively decreased inflammation, inhibited the rise in NOS activity, and provided protection against glutathione depletion.

Exploring the NRF2/HO-1 and NF-κB Pathways: Spirulina Nanoparticles as a Novel Approach to Combat Diabetic Nephropathy

Arthrospira platensis has been the subject of plentiful studies due to its purported health advantages; nevertheless, additional investigation is required to determine whether several chronic diseases may be treated or avoided with its nanoform. Therefore, we set out to examine A. platensis nanoparticles (SNPs) to protect against kidney impairment caused by Streptozotocin (STZ) in diabetic rats, precisely focusing on its effect and the cellular intracellular pathways involved. Male Wistar rats were assigned into four groups: Group 1 was set as control, comprising the normal rats; group 2 was administered SNPs (0.5 mg/kg BW, once/day) orally for 84 consecutive days; group 3, STZ-diabetic rats were injected with STZ (65 mg/kg BW); and group 4, in which the diabetic rats were treated with SNPs. After inducing diabetes in rats for 84 days, the animals were euthanized. The results disclosed that SNP treatment substantially (P < 0.05) improved the glucose and glycated hemoglobin levels (HbA1c %), insulin, C-peptide, and cystatin C deterioration in diabetic rats. Furthermore, SNP administration significantly lowered (P < 0.05) nitric oxide (NO) and malondialdehyde (MDA) levels in renal tissue and enhanced kidney function metrics, as well as improved the antioxidant capacity of the renal tissue. In addition, oral SNPs overcame the diabetic complications concerning diabetic nephropathy, indicated by downregulation and upregulation of apoptotic and antiapoptotic genes, respectively, along with prominent modulation of the antiangiogenic marker countenance level, improving kidney function. SNP modulated the nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 (NRF2/HO-1) pathways and inhibited the nuclear factor-κB (NF-κB) expression, strengthening the SNP pathways in alleviating diabetic nephropathy. The histopathology results corroborated the obtained biochemical and molecular observations, suggesting the therapeutic potential of SNPs in diabetic nephropathy via mechanisms other than its significant antioxidant and hypoglycemic effects, including modulation of antiangiogenic and inflammatory mediators and the NRF2/HO-1 pathways.

Induction of Diabetes Mellitus Using Alloxan in Sprague Dawley Rats

PURPOSE

The use of rodent models for diabetes, particularly with pancreatic islet transplantation, has been prevalent in various preclinical trials. The purpose of this study is to establish a diabetes mellitus (DM) model in Sprague Dawley (SD) rats using alloxan evaluated by assessing alloxan dosage, the induction rate of diabetes, and glucose stability through insulin treatment.

METHODS

Over the course of 13 experimental rounds, diabetes was induced in 86 SD rats using alloxan at concentrations of 200 mg/kg (16 rats) or 150 mg/kg (70 rats). Various parameters, including diabetes induction rates, average insulin doses, extent of weight loss, and adverse effects such as diabetic ketoacidosis (DKA), were measured.

RESULTS

The administration of 200 mg/kg of alloxan in rats resulted in severe diabetes induction, leading to DKA in three individuals, despite daily insulin glargine administration, DKA prevention was unsuccessful. The stability of alloxan decreases over time, especially when refrigeration is compromised during weighing. In the group treated with 150 mg/kg of alloxan, the diabetes induction rate was 83%. The average insulin dose was 2.21 units/kg/day. In contrast, the group treated with 200 mg/kg of alloxan exhibited a diabetes induction rate of 81% with a statistically significant higher average insulin requirement at 7.58 units/kg/day compared to 150 mg/kg of alloxan.

CONCLUSION

Inducing diabetes in rats with 150 mg/kg of alloxan is considered more suitable for creating a diabetes model for xenogeneic islet transplantation compared to using 200 mg/kg of alloxan. This is due to fewer complications related to DKA or hyperglycemia and reduced need for exogenous insulin treatment.

Progress in experimental models to investigate the in vivo and in vitro antidiabetic activity of drugs

Diabetes mellitus is one of the world's most prevalent and complex metabolic disorders, and it is a rapidly growing global public health issue. It is characterized by hyperglycemia, a condition involving a high blood glucose level brought on by deficiencies in insulin secretion, decreased activity of insulin, or both. Prolonged effects of diabetes include cardiovascular problems, retinopathy, neuropathy, nephropathy, and vascular alterations in both macro- and micro-blood vessels. In vivo and in vitro models have always been important for investigating and characterizing disease pathogenesis, identifying targets, and reviewing novel treatment options and medications. Fully understanding these models is crucial for the researchers so this review summarizes the different experimental in vivo and in vitro model options used to study diabetes and its consequences. The most popular in vivo studies involves the small animal models, such as rodent models, chemically induced diabetogens like streptozotocin and alloxan, and the possibility of deleting or overexpressing a specific gene by knockout and transgenic technologies on these animals. Other models include virally induced models, diet/nutrition induced diabetic animals, surgically induced models or pancreatectomy models, and non-obese models. Large animals or non-rodent models like porcine (pig), canine (dog), nonhuman primate, and Zebrafish models are also outlined. The in vitro models discussed are murine and human beta-cell lines and pancreatic islets, human stem cells, and organoid cultures. The other enzymatic in vitro tests to assess diabetes include assay of amylase inhibition and inhibition of α-glucosidase activity.

Pistacia lentiscus: Phytochemistry and Antidiabetic Properties

Pistacia lentiscus L. (P. lentiscus) is an evergreen shrub (Anacardiaceae family) primarily found in the Mediterranean region. The plant has been thoroughly characterized, resulting in a high concentration of bioactive compounds as flavonoids and phenolics. Moreover, P. lentiscus was revealed to possess a great nutritional and industrial importance because of its variety of biological activities, including antibacterial, anti-inflammatory, anti-atherogenic and antioxidant properties. Many of its beneficial health properties and applications date back to antiquity, and the European Medicines Agency officially acknowledged it as an herbal medicinal product. Indeed, it is widely employed in conventional medicine to treat several diseases, including type 2 diabetes (T2D). On this basis, this review aims to summarize and describe the chemical composition of different parts of the plant and highlight the potential of P. lentiscus, focusing on its antidiabetic activities. The plant kingdom is drawing increasing attention because of its complexity of natural molecules in the research of novel bioactive compounds for drug development. In this context, P. lentiscus demonstrated several in vitro and in vivo antidiabetic effects, acting upon many therapeutic T2D targets. Therefore, the information available in this review highlighted the multitarget effects of P. lentiscus and its great potential in T2D treatment.

A Holistic In Silico and In Vivo Approach to Exploring the Antidiabetic, Antioxidant, and Hepatoprotective Properties of Rose of Sharon

Diabetes mellitus (DM) is a significant global health burden that necessitates the exploration of effective and accessible therapeutic options. Phytotherapy has played a vital role in healthcare, with plant extracts being integral to traditional medicinal practices. The therapeutic potential of Hibiscus syriacus (Rose of Sharon), a plant with a rich ethnobotanical history, in the management of DM and its associated complications was investigated. In this study, the therapeutic potential of Hibiscus syriacus L. extract (HSE) against DM in streptozotocin (STZ)-induced diabetic rats was assessed, focusing on its effects on glucose regulation, antioxidative defense, and liver protection. The administration of the HSE extract substantially reduced hyperglycemia and increased insulin production, with concurrent improvements in body weight and hydration. The enhanced activity of antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), suggests reduced oxidative stress, which is further supported by molecular docking results with the 3GTV superoxide dismutase enzyme, showing a binding energy of -6.3 kcal/mol. A decrease in MDA levels also indicates a reduction in oxidative stress. Notably, HSE treatment led to decreased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and improved lipid profiles, indicating its hepatoprotective and lipid-modifying benefits. These findings support the inclusion of HSE as an adjunctive therapy in DM management strategies. This study promotes the consideration of Hibiscus syriacus L. therapeutic properties in global health contexts.

Therapeutical Potential of T3 as Adjuvant Therapy in Male Alloxan-induced Diabetic Rats

Alloxan-induced diabetic rats present with hypothyroidism. When treated with triiodothyronine (T3), glycemia and proinflammatory cytokine expression are downregulated, improving insulin sensitivity. The effectiveness of associating T3 with insulin (replacement dose [6 U] and [3 U]) in controlling glycemia was investigated in this experimental model. Male Wistar rats were made diabetic by alloxan injection and sorted into groups treated or not with insulin (3 or 6 U) associated or not with T3 (1.5 µg 100 g-1 BW) for 28 days. Nondiabetic rats constituted the control group. Fasting glycemia, glucose decay rate, and thyrotropin (TSH) were measured in the blood/serum of all animals. Immunoblotting was used to assess total GLUT4 expression in skeletal muscles and epididymal white adipose tissue. Cytokine and nuclear factor-κB (NF-κB) expression were measured in these tissues and liver. Diabetic rats presented with increased fasting glycemia, inflammatory cytokines, and NF-κB expression, TSH levels, and insulin resistance. In diabetic rats treated with T3 and/or insulin, these parameters were decreased, whereas GLUT4 and anti-inflammatory cytokine expression were increased. T3 combined with 3-U insulin restored the parameters to values of the control group and was more effective at controlling glycemia than 6-U insulin. Thus, a combination of T3 and insulin might represent a promising strategy for diabetes management since it reduces the insulin requirement by half and improves glycemic control of diabetic rats, which could postpone insulin resistance that develops with chronic insulin administration. These findings open a perspective for using thyroid analogues that provide tissue-specific effects, which might result in a potentially more effective treatment of diabetes.

GHSR Deletion in β-Cells of Male Mice: Ineffective in Obesity, but Effective in Protecting against Streptozotocin-Induced β-Cell Injury in Aging

Insulin secretion from pancreatic β cells is a key pillar of glucose homeostasis, which is impaired under obesity and aging. Growth hormone secretagogue receptor (GHSR) is the receptor of nutrient-sensing hormone ghrelin. Previously, we showed that β-cell GHSR regulated glucose-stimulated insulin secretion (GSIS) in young mice. In the current study, we further investigated the effects of GHSR on insulin secretion in male mice under diet-induced obesity (DIO) and streptozotocin (STZ)-induced β-cell injury in aging. β-cell-specific-Ghsr-deficient (Ghsr-βKO) mice exhibited no glycemic phenotype under DIO but showed significantly improved ex vivo GSIS in aging. We also detected reduced insulin sensitivity and impaired insulin secretion during aging both in vivo and ex vivo. Accordingly, there were age-related alterations in expression of glucose transporter, insulin signaling pathway, and inflammatory genes. To further determine whether GHSR deficiency affected β-cell susceptibility to acute injury, young, middle-aged, and old Ghsr-βKO mice were subjected to STZ. We found that middle-aged and old Ghsr-βKO mice were protected from STZ-induced hyperglycemia and impaired insulin secretion, correlated with increased expression of insulin signaling regulators but decreased pro-inflammatory cytokines in pancreatic islets. Collectively, our findings indicate that β-cell GHSR has a major impact on insulin secretion in aging but not obesity, and GHSR deficiency protects against STZ-induced β-cell injury in aging.

Silibinin as a promising treatment for diabetes: Insights into behavioral and metabolic changes in an animal model

Diabetes mellitus is causing serious health problems in the chronic period. Silibinin is a flavonoid obtained from the milk thistle (Silybum marianum), which is among the herbal ethnopharmacological administrations. In studies with silibinin, it has been reported that it increases the activity of pancreatic beta cells and insulin sensitivity and has a hyperglycemia-reducing effect. However, behavioral parameters have not been evaluated together with insulin levels and liver function tests. Our aim in this study was to examine the effects of silibinin on insulin secretion, anxiety-like behaviors, and learning in a streptozotocin (STZ)-induced rat diabetes model. Wistar albino rats weighing 200-250 g were divided into 4 groups. Control: Saline solution, Diabetes: STZ 45 mg/kg, S 100: STZ 45 mg/kg + Silibinin 100 mg/kg, S 200: STZ 45 mg/kg + Silibinin 200 mg/kg. Administrations were continued for 21 days. On the 21st day, open field and elevated plus maze as unconditional anxiety tests; Barnes maze for learning and memory; and rotarod test for locomotor activity were conducted. Following behavioral tests, blood samples were taken under anesthesia. Blood glucose levels and ALT values were measured. Insulin levels were measured with an ELISA plate reader. Silibinin shortened the time to find the correct hole. Silibinin prevented the decrease in insulin due to STZ, exhibited a hyperglycemia-reducing effect and decreased the elevation of ALT.

Current advancement in the preclinical models used for the assessment of diabetic neuropathy

Diabetic neuropathy is one of the prevalent and debilitating microvascular complications of diabetes mellitus, affecting a significant portion of the global population. Relational preclinical animal models are essential to understand its pathophysiology and develop effective treatments. This abstract provides an overview of current knowledge and advancements in such models. Various animal models have been developed to mimic the multifaceted aspects of human diabetic neuropathy, including both type 1 and type 2 diabetes. These models involve rodents (rats and mice) and larger animals like rabbits and dogs. Induction of diabetic neuropathy in these models is achieved through chemical, genetic, or dietary interventions, such as diabetogenic agents, genetic modifications, or high-fat diets. Preclinical animal models have greatly contributed to studying the intricate molecular and cellular mechanisms underlying diabetic neuropathy. They have shed light on hyperglycemia-induced oxidative stress, neuroinflammation, mitochondrial dysfunction, and altered neurotrophic factor signaling. Additionally, these models have allowed for the investigation of morphological changes, functional alterations, and behavioral manifestations associated with diabetic neuropathy. These models have also been crucial for evaluating the efficacy and safety of potential therapeutic interventions. Novel pharmacological agents, gene therapies, stem cell-based approaches, exercise, dietary modifications, and neurostimulation techniques have been tested using these models. However, limitations and challenges remain, including physiological differences between humans and animals, complex neuropathy phenotypes, and the need for translational validation. In conclusion, preclinical animal models have played a vital role in advancing our understanding and management of diabetic neuropathy. They have enhanced our knowledge of disease mechanisms, facilitated the development of novel treatments, and provided a platform for translational research. Ongoing efforts to refine and validate these models are crucial for future treatment developments for this debilitating condition.

Treating neuropathic pain and comorbid affective disorders: Preclinical and clinical evidence

INTRODUCTION

Neuropathic pain (NP) significantly impacts quality of life and often coexists with affective disorders such as anxiety and depression. Addressing both NP and its psychiatric manifestations requires a comprehensive understanding of therapeutic options. This study aimed to review the main pharmacological and non-pharmacological treatments for NP and comorbid affective disorders to describe their mechanisms of action and how they are commonly used in clinical practice.

METHODS

A review was conducted across five electronic databases, focusing on pharmacological and non-pharmacological treatments for NP and its associated affective disorders. The following combination of MeSH and title/abstract keywords were used: "neuropathic pain," "affective disorders," "depression," "anxiety," "treatment," and "therapy." Both animal and human studies were included to discuss the underlying therapeutic mechanisms of these interventions.

RESULTS

Pharmacological interventions, including antidepressants, anticonvulsants, and opioids, modulate neural synaptic transmission to alleviate NP. Topical agents, such as capsaicin, lidocaine patches, and botulinum toxin A, offer localized relief by desensitizing pain pathways. Some of these drugs, especially antidepressants, also treat comorbid affective disorders. Non-pharmacological techniques, including repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and photobiomodulation therapy, modulate cortical activity and have shown promise for NP and mood disorders.

CONCLUSIONS

The interconnection between NP and comorbid affective disorders necessitates holistic therapeutic strategies. Some pharmacological treatments can be used for both conditions, and non-pharmacological interventions have emerged as promising complementary approaches. Future research should explore novel molecular pathways to enhance treatment options for these interrelated conditions.

Appropriate glycemic management protects the germline but not the uterine environment in hyperglycemia

Emerging evidence indicates that parental diseases can impact the health of subsequent generations through epigenetic inheritance. Recently, it was shown that maternal diabetes alters the metaphase II oocyte transcriptome, causing metabolic dysfunction in offspring. However, type 1 diabetes (T1D) mouse models frequently utilized in previous studies may be subject to several confounding factors due to severe hyperglycemia. This limits clinical translatability given improvements in glycemic control for T1D subjects. Here, we optimize a T1D mouse model to investigate the effects of appropriately managed maternal glycemic levels on oocytes and intrauterine development. We show that diabetic mice with appropriate glycemic control exhibit better long-term health, including maintenance of the oocyte transcriptome and chromatin accessibility. We further show that human oocytes undergoing in vitro maturation challenged with mildly increased levels of glucose, reflecting appropriate glycemic management, also retain their transcriptome. However, fetal growth and placental function are affected in mice despite appropriate glycemic control, suggesting the uterine environment rather than the germline as a pathological factor in developmental programming in appropriately managed diabetes.

Antioxidant and anti-inflammatory effects of Boswellia dalzielii and Hibiscus sabdariffa extracts in alloxan-induced diabetic rats

Diabetes mellitus (DM) is one of the leading worldwide public health problems. It is characterized by hyperglycemia which induces oxidative stress and inflammation, both involved in the pathogenesis of diabetes. We previously showed that Boswellia dalzielii (BD) and Hibiscus sabdariffa (HS) extracts reduced hyperglycemia and hyperlipidemia in alloxan-induced diabetic rats. In the present study, we evaluated the antioxidant and anti-inflammatory activities of both plants in alloxan-induced diabetic rats. Two sets of experiments were conducted in male Wistar rats subjected to a single intraperitoneal injection of alloxan monohydrate (150 mg/kg, b. w.). Then, diabetic rats were daily administered with either BD (1st set of experiments) or HS (2nd set of experiments) at 100, 200, and 400 mg/kg orally for 21 consecutive days. Glibenclamide (10 mg/kg) was also administered as a reference drug. At the end of the study, the animals were anesthetized, and blood samples were collected from each animal. Then, oxidative stress and inflammatory biomarkers in the serum were determined. We found that treatment with BD and HS significantly reduced malondialdehyde (MDA) and enhanced the levels of reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT). These extracts also significantly decreased the inflammatory markers tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β). From the results obtained, it can therefore be concluded that BD and HS have the potential to being developed as natural sources of antioxidant and anti-inflammatory agents that can be used for the prevention or treatment of DM.

Chromium Picolinate Regulates Bone Metabolism and Prevents Bone Loss in Diabetic Rats

Diabetic osteoporosis (DOP) is an abnormal metabolic disease caused by long-term hyperglycemia. In this study, a model rat of streptozotocin (STZ)-induced diabetes was established, and chromium picolinate (5 mg·kg-1) was given; the changes in blood glucose and body weight were detected before and after administration; and bone mineral density (BMD), bone morphology, bone turnover markers, inflammatory cytokines, and oxidative stress indicators were observed in each group. We found that after chromium picolinate (CP) intervention for 8 weeks, the blood glucose level was decreased; the BMD, the bone histomorphology parameters, and the pathological structure were improved; the expression of bone resorption-related proteins was downregulated; and the expression of bone formation-related proteins was upregulated. Meanwhile, serum antioxidant activity was increased, and inflammatory cytokine levels were decreased. In conclusion, CP could alleviate DOP by anti-oxidation, inhibition of bone turnover, anti-inflammation, and regulation of the OPG/RANKL/RANK signaling pathway. Therefore, CP has important application values for further development as a functional food or active medicine in DOP treatment.

Anti-Diabetic Potentials of Lactobacillus Strains by Modulating Gut Microbiota Structure and β-Cells Regeneration in the Pancreatic Islets of Alloxan-Induced Diabetic Rats

Diabetes mellitus, a most common endocrine disorder of glucose metabolism, has become a global epidemic and poses a serious public health threat with an increased socio-economic burden. Escalating incidence of diabetes is correlated with changes in lifestyle and food habits that cause gut microbiome dysbiosis and β-cells damage, which can be addressed with dietary interventions containing probiotics. Hence, the search for probiotics of human origin with anti-diabetic, anti-AGE, and anti-ACE potentials has gained renewed interest for the effective management of diabetes and its associated complications. The present study used an alloxan (AXN)-induced diabetic rat model to investigate the effects of potential probiotic Lacticaseibacillus casei MKU1, Lactiplantibacillus pentosus MKU3, and Lactiplantibacillus plantarum MKU7 administration individually on physiochemical parameters related to diabetic pathogenesis. Experimental animals were randomly allotted into six groups viz. NCG (control), DCG (AXN), DGM (metformin), DGP1 (MKU1), DGP2 (MKU3), and DGP3 (MKU7), and biochemical data like serum glucose, insulin, AngII, ACE, HbA1c, and TNF-α levels were measured until 90 days. Our results suggest that oral administration with MKU1, MKU3, or MKU7 significantly improved serum insulin levels, glycemic control, glucose tolerance, and body weight. Additionally, β-cell mass was increased by preserving islet integrity in Lactobacillus-treated diabetic rats, whereas TNF-α (~40%), AngII (~30%), and ACE levels (~50%) were strongly inhibited and enhanced sIgA production (5.8 folds) abundantly. Furthermore, Lactobacillus administration positively influenced the gut microbiome with a significant increase in the abundance of Lactobacillus species and the beneficial Bacteroides uniformis and Bacteroides fragilis, while decreased the pathogenic Proteus vulgaris and Parabacteroides distasonis. Among the probiotic treatment groups, L. pentosus MKU3 performed greatly in almost all parameters, indicating its potential use for alleviating diabetes-associated complications.

Hippocampal acetylcholine receptor activation-dependent long-term depression in streptozotocin-induced diabetic rats

Cholinergic innervation of the hippocampus correlates with memory formation. In a well-established animal model of type 1 diabetes mellitus, obtained by injecting young adult rats with streptozotocin (STZ), reductions have been reported in the expression of acetylcholine receptors and choline acetyltransferase. In this study, we showed that long-term synaptic depression (LTD) induced by carbachol (CCh), a nonselective cholinergic receptor agonist, at Schaffer collateral-CA1 synapses in hippocampal slices was significantly weaker in streptozotocin-induced diabetic rats (STZ rats) than in age-matched control rats. No significant change was observed in the paired-pulse ratio between before and 80 min after the application of CCh in control and STZ rats. Moreover, CCh-induced LTD in control and STZ rats was not affected by an NMDA receptor antagonist. Although the application of CCh down-regulated the surface expression of GluA2 in the hippocampus of control rats, but not STZ rats. Therefore, the present results suggest that acetylcholine receptor-mediated LTD in STZ rats requires the internalization of AMPA receptors on the postsynaptic surface and their intracellular effects in the hippocampus.

New Dipterocarpol-Based Molecules with α-Glucosidase Inhibitory and Hypoglycemic Activity

Dammarane triterpenoids are affordable and bioactive natural metabolites with great structural potential, which makes them attractive sources for drug development. The aim of the study was to investigate the potency of new dipterocarpol derivatives for the treatment of diabetes. Two dammaranes (dipterocarpol and its 20(24)-diene derivative) were modified by a Claisen-Schmidt aldol condensation to afford C2(E)-arylidenes in good yields. The majority of the synthesized compounds exhibited an excellent-to-moderate inhibitory effect toward α-glucosidase (from S. saccharomyces), among them eight compounds showed IC50 values less than 10 μM. 3-Oxo-dammarane-2(E)-benzylidenes (holding p-hydroxy- 3 l and p-carbonyl- 3 m substituents) demonstrated the most potent α-glucosidase inhibition with IC50 0.753 and 0.204 μM, being 232- and 857-times more active than acarbose (IC50 174.90 μM), and a high level of NO inhibition in Raw 264.7 cells with IC50 of 1.75 and 4.57 μM, respectively. An in vivo testing of compound 3 m (in a dose of 20 mg/kg) on a model of streptozotocin-induced T1DM in rats showed a pronounced hypoglycemic activity, the ability to reduce effectively the processes of lipid peroxidation in liver tissue and decrease the excretion of glucose and pyruvic acid in the urine. Compound 3 m reduced the death of diabetic rats and preserved their motor activity.

Alterations of the glutamatergic system in diabetes mellitus

Diabetes mellitus (DM) is a chronic disease characterized by elevated blood glucose levels caused by a lack of insulin production (type 1 diabetes) or insulin resistance (type 2 diabetes). It is well known that DM is associated with cognitive deficits and metabolic and neurophysiological changes in the brain. Glutamate is the main excitatory neurotransmitter in the central nervous system that plays a key role in synaptic plasticity, learning, and memory processes. An increasing number of studies have suggested that abnormal activity of the glutamatergic system is implicated in the pathophysiology of DM. Dysfunction of glutamatergic neurotransmission in the central nervous system can provide an important neurobiological substrate for many disorders. Magnetic resonance spectroscopy (MRS) is a non-invasive technique that allows a better understanding of the central nervous system factors by measuring in vivo the concentrations of brain metabolites within the area of interest. Here, we briefly review the MRS studies that have examined glutamate levels in the brain of patients with DM. The present article also summarizes the available data on abnormalities in glutamatergic neurotransmission observed in different animal models of DM. In addition, the role of gut microbiota in the development of glutamatergic alterations in DM is addressed. We speculate that therapeutic strategies targeting the glutamatergic system may be beneficial in the treatment of central nervous system-related changes in diabetic patients.

Trichosanthin alleviates streptozotocin-induced type 1 diabetes mellitus in mice by regulating the balance between bone marrow-derived IL6+ and IL10+ MDSCs

Myeloid-derived suppressor cells (MDSCs) occupy a pivotal role in the intricate pathogenesis of the autoimmune disorder, Type 1 diabetes mellitus (T1DM). Since our previous work demonstrated that trichosanthin (TCS), an active compound of Chinese herb medicine Tian Hua Fen, regulated immune response, we aimed to clarify the efficacy and molecular mechanism of TCS in the treatment of T1DM. To this end, T1DM mouse model was established by streptozotocin (STZ) induction. The mice were randomly divided into normal control group (Ctl), T1DM group (STZ), TCS treated diabetic group (STZ + TCS) and insulin-treated diabetic group (STZ + insulin). Our comprehensive evaluation encompassed variables such as blood glucose, glycosylated hemoglobin, body weight, pertinent biochemical markers, pancreatic histopathology, and the distribution of immune cell populations. Furthermore, we meticulously isolated MDSCs from the bone marrow of T1DM mice, probing into the expressions of genes pertaining to the advanced glycation end product receptor (RAGE)/NF-κB signaling pathway through RT-qPCR. Evidently, TCS exhibited a substantial capacity to effectively counteract the T1DM-induced elevation in random blood glucose, glycosylated hemoglobin, and IL-6 levels in plasma. Pathological scrutiny underscored the ability of TCS to mitigate the damage incurred by islets. Intriguingly, TCS interventions engendered a reduction in the proportion of MDSCs within the bone marrow, particularly within the IL-6+ MDSC subset. In contrast, IL-10+ MDSCs exhibited an elevation following TCS treatment. Moreover, we observed a significant down-regulation of relative mRNA of pro-inflammatory genes, including arginase 1 (Arg1), inducible nitric oxide synthase (iNOS), RAGE and NF-κB, within MDSCs due to the influence of TCS. It decreases total MDSCs and regulates the balance between IL-6+ and IL-10+ MDSCs thus alleviating the symptoms of T1DM. TCS also down-regulates the RAGE/NF-κB signaling pathway, making it a promising alternative therapeutic treatment for T1DM. Collectively, our study offered novel insights into the underlying mechanism by which TCS serves as a promising therapeutic intervention for T1DM.

Rational Engineering of Islet Tolerance via Biomaterial-Mediated Immune Modulation

Type 1 diabetes (T1D) onset is characterized by an autoimmune attack on β islet cells within the pancreas, preventing the insulin secretion required to maintain glucose homeostasis. Targeted modulation of key immunoregulatory cell populations is a promising strategy to restore tolerance to β cells. This strategy can be used to prevent T1D onset or reverse T1D with transplanted islets. To this end, drug delivery systems can be employed to transport immunomodulatory cargo to specific cell populations that inhibit autoreactive T cell-mediated destruction of the β cell mass. The rational engineering of biomaterials into nanoscale and microscale drug carriers can facilitate targeted interactions with immune cells. The physicochemical properties of the biomaterial, the delivered immunomodulatory agent, and the target cell populations are critical variables in the design of these delivery systems. In this review, we discuss recent biomaterials-based drug delivery approaches to induce islet tolerance and the need to consider both immune and metabolic markers of disease progression.

Metabolite profiling and biochemical investigation of the antidiabetic potential of Loranthus pulverulentus Wall n-butanol fraction in diabetic animal models

ETHNOPHARMACOLOGICAL RELEVANCE

Globally, 537 million individuals are estimated to have diabetes. The traditional use of herbs for ameliorating diabetes symptoms is a common practice in Pakistan and use of Loranthus pulverulentus Wall (L. pulverulentus) by local people in Azad Jammu and Kashmir has been reported.

AIM OF THE STUDY

In the present study, the antidiabetic potential of standardized n-butanol fraction of leaves of L. pulverulentus Wall, which is a parasite of Dalbergia sisso Roxb was assessed in both alloxan (ALX) and streptozotocin (STZ) diabetic animal models.

MATERIALS AND METHODS

Chemical characterization of BF was performed using HPLC, GCMS and UHPLC-MS. The effect of the fraction (250 mg/kg) on insulin, plasma free fatty acids, L-lactate, pyruvate, MDA, HbA1c and glycogen levels in ALX and STZ animal models was determined. Liver and renal profiles were analyzed in the STZ model. Toxicological studies were performed by hemolytic, Ames mutagenicity, DNA protection, and thrombolytic assays. Histopathological analysis of the pancreas, liver, and kidney was performed.

RESULTS

BF demonstrated highly significant (p < 0.001) antidiabetic potential in both diabetic models. BF significantly (p < 0.05) improved OGTT results in alloxanized diabetic mice and blocked the absorption of glucose from the gut. A significant (p < 0.001) increase in insulin levels and glycogen content in liver tissue and a decrease in plasma FFA, MDA, HbA1c, L-lactate, and pyruvate levels in STZ-diabetic mice were recorded. GC-MS and chromatographic analysis showed the presence of catechin, eugenol, longifolene, caryophyllene, Ar-tumerone and Geranyl-alpha-terpinene. Various metabolites with antidiabetic potential, including 4-hydroxycinnamyl alcohol 4-D-glucoside, zingerone glucoside, trans-trismethoxy resveratrol-d4, epigallocatechin 3-O-cinnamate, and β-glucogallin, were identified using UHPLC-MS. Animals treated with BF showed marked improvements in cellular structures of the pancreas, liver and kidneys. This fraction is non-mutagenic and protects the DNA.

CONCLUSION

The experimental fraction contained potential antidiabetic bioactive compounds responsible for alleviating diabetes-associated biochemical dysregulation. The fraction increased insulin levels and enhanced glycogen storage in muscles and the liver. It blocked glucose absorption from the intestine and substantially decreased HbA1c, lactate, pyruvate, free fatty acids, lipid, liver and kidney damage. Therefore, the use of BF for the treatment of type-2 diabetes may be beneficial.

Animal Models of Type 2 Diabetes Complications: A Review

Diabetes mellitus is a multifactorial metabolic disease, of which type 2 diabetes (T2D) is one of the most common. The complications of diabetes are far more harmful than diabetes itself. Type 2 diabetes complications include diabetic nephropathy (DN), diabetic heart disease, diabetic foot ulcers (DFU), diabetic peripheral neuropathy (DPN), and diabetic retinopathy (DR) et al. Many animal models have been developed to study the pathogenesis of T2D and discover an effective strategy to treat its consequences. In this sense, it is crucial to choose the right animal model for the corresponding diabetic complication. This paper summarizes and classifies the animal modeling approaches to T2D complications and provides a comprehensive review of their advantages and disadvantages. It is hopeful that this paper will provide theoretical support for animal trials of diabetic complications.

Synergistic Effect of Naringin and Glimepiride in Streptozotocin-induced Diabetic Rats

OBJECTIVE

Evaluation of the synergistic effect of Naringin and Glimepiride in streptozotocin (STZ)-induced diabetic rats.

METHODS

Wistar rats were chosen and divided into five groups (n=6). STZ was used for the induction of diabetes. The combination of naringin and glimepiride was administered to diabetic rats. The changes in fasting blood sugar, body weight, Hb, HbA1c, and creatinine were evaluated, and urine was collected and the volume was observed. The lipid profiles like TC, HDL, LDL, and TG were measured. The biochemical parameters SGOT, SGPT, and ALP were analysed. Besides, endogenous antioxidant parameters like SOD, GSH, and catalase were also assessed. Lastly, the histopathological study of the beta cells in islets of the pancreas, glomerulus, and tubules of kidney and liver cells was conducted in all groups.

RESULTS

The result shows significant reduction (p<0.001) of blood sugar in the naringin and glimepiride-treated group when compared with the control group (diabetes). Additionally, the combination of Naringin (100 mg/kg) and Glimepiride (0.1 mg/kg) significantly restores the creatinine levels and urine volumes, SGOT, SGPT, and ALP when compared to a single dose of administration. Further, the abnormal lipid profile levels (TC, LDL, TG, and HDL), and endogenous antioxidant enzymes (SOD, GSH, catalase) in diabetic control rats were restored to normal levels in a significant manner. The histopathological result reveals significant alterations, including hypertrophy of islets and mild degeneration, renal necrosis, and inflammation of hepatocytes.

CONCLUSION

A synergistic effect of Naringin and glimepiride was observed during the estimation of various biochemical parameters like body weight, fasting blood sugar, creatinine, urine level, TG, total cholesterol, SGOT, SGPT, ALP, Insulin, HbA1c, antioxidant parameters like SOD, GSH, and catalase in STZ-induced diabetic rats. Further, the combination of therapy improves the protective effect of the pancreas, kidney, and liver, suggesting a potential antidiabetic effect.

Phytochemical Analysis and hypoglycemic potential of Filago hurdwarica (Wall. ex DC.) Wagenitz in alloxan induced diabetic mice

Abstract Plants have profound therapeutic benefits, more economical treatments, fewer side effects, and a relatively cheap cost, making them a source of drugs for protective, preventative, curative, or conducive purposes and creating novel phytomedicines. Plant derived medicines are relatively safe compared to synthetic medicines. Many plants have proved to successfully aid in the treatment of diabetes including Filago hurdwarica (Wall. ex DC.) Wagenitz. The current investigations were therefore designed to assess the phytochemical, antioxidant, antidiabetic, and antihyperlipidemic activities of F. hurdwarica. The phytochemical investigations and antioxidant activities of different extracts were carried out using standard chemical tests, DPPH, and H2O2 scavenging assays. F. hurdwarica plant extract in Hydromethanolic solution were prepared by Soxhletation method and stored in refrigerator at 4°C for two days before use. Swiss Albino mice were made diabetic by a single dose of alloxan (150 mg/kg). Hydromethanolic plant extract and fractions of F. hurdwarica were screened for antidiabetic activity and given to the alloxan-induced diabetic mice at a concentration of 150-250 mg/kg of body weight in different groups of 6 diabetic mice each orally once a day for 15 days. Glibenclamide is also given to another group to as a standard drug to support the result at a dose of 10 mg/kg of body weight orally once a day for 15 days. Blood glucose levels and body weights of mice were measured on 0, 4, 7, 11 and 15th days. The study found that the extract was safe up to the dose level of 2000 mg/kg and the dose response effect of chloroform extract (150-250 mg/kg) of F. hurdwarica showed expressive antihyperglycemic effects and also improved other altered biochemical parameters associated with diabetes. The FTIR and XRD spectra demonstrated the occurrence of phenols, alcohols, alkenes, alkyl halides, ketones, and aromatic compounds and confirmed the amorphous nature of the extract. GC-MS spectral analysis showed the tentative presence of 31 phytochemical constituents in the chloroform extract of F. hurdwarica with different retention time. To conclude, the chloroform extract (250 mg/kg) of F. hurdwarica revealed considerable antioxidant, antihyperglycemic, and antihyperlipidemic potential and is safe for treating diabetes and related complications.

Blockage of DCLK1 in cardiomyocytes suppresses myocardial inflammation and alleviates diabetic cardiomyopathy in streptozotocin-induced diabetic mice

Diabetic cardiomyopathy (DCM) is a pathophysiological condition triggered by diabetes mellitus and can lead to heart failure. Doublecortin-like kinase protein 1 (DCLK1) is a multifunctional protein kinase involved in the regulation of cell proliferation, differentiation, survival, and migration. Current studies on DCLK1 mainly focus on cancer development; however, its role in non-tumor diseases such as DCM is yet to be deciphered. Our analysis revealed that DCLK1 was upregulated in cardiomyocytes of streptozotocin (STZ)-induced type 1 diabetic mouse, suggesting a correlation between DCLK1 and DCM progression. It was further demonstrated that either cardiomyocyte-specific DCLK1 knockout or pharmacological DCLK1 inhibitor DCLK1-IN-1 significantly alleviated cardiac hypertrophy and fibrosis in STZ-induced diabetic mice. RNA-seq analysis of heart tissues revealed that DCLK1 regulated the nuclear factor kappa B (NF-κB)-mediated inflammatory response in DCM. In vitro, DCLK1 activated NF-κB and the inflammatory response by inducing the IKKβ phosphorylation in high-concentration glucose (HG)-challenged cardiomyocytes. DCLK1-IN-1 also prevented HG-induced IKKβ/NF-κB activation and inflammatory injuries in cardiomyocytes. In conclusion, this study highlights the novel role of cardiomyocyte DCLK1 in regulating IKKβ/NF-κB, which aggravates inflammation to promote the pathogenesis of DCM. DCLK1 may serve as a new target for DCM treatment.

Antidiabetic and hepato-renal protective effects of medicinal plants in STZ induced diabetic rats

Abstract The antidiabetic and hepato-renal protective effects of Citrullus colocynthis and Momordica charantia ethanol extracts were investigated in streptozotocin (STZ) induced diabetic male albino rats. Diabetic rats were treated with C. colocynthis, M. charantia or C. colocynthis + M. charantia mixed extract at a dose of 250 mg /kg body weight per oral per day for 21 days. The mean body weight of all the diabetic rat groups on day 1 of treatment (day 10 of diabetes) was significantly lower than the normal control rat group (P<0.05). The blood glucose level of all the diabetic rat groups on day 1 of treatment (day 10 of diabetes) was significantly (P<0.05) higher (> 200 mg/dl) than the normal control rat group (95.5 ± 2.7). At the end of treatment (day 21), the diabetic rats treated with plant extracts showed significant increase (P<0.05) in body weight and significant (P<0.05) reduction in blood glucose level when compared to diabetic control animals. Significant increase (< 0.05) was observed in the serum bilirubin, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), urea and creatinine levels of diabetic control rat group. The serum levels of these liver and kidney-related parameters of diabetic rats treated with plant extract were significantly lower when compared to diabetic control rat group (p < 0.05). Photomicrographs of liver and kidney microsections from diabetic rats treated with these plant extracts showed amelioration in the hepato-renal histoarchitectures. It was concluded that the C. colocynthis and M. charantia methanol extracts are antidiabetic and hepato-renal protective in STZ induced diabetic male rats. Treatment of the diabetic rats with C. colocynthis + M. charantia mixed extract is more effective in the amelioration of diabetes and hepato-renal injuries in STZ induced diabetic male rats.

The Anti-Diabetic Potential of Baicalin: Evidence from Rodent Studies

Baicalin is a biologically active flavonoid compound that benefits the organism in various pathological conditions. Rodent studies have shown that this compound effectively alleviates diabetes-related disturbances in models of type 1 and type 2 diabetes. Baicalin supplementation limited hyperglycemia and improved insulin sensitivity. The anti-diabetic effects of baicalin covered the main insulin-sensitive tissues, i.e., the skeletal muscle, the adipose tissue, and the liver. In the muscle tissue, baicalin limited lipid accumulation and improved glucose transport. Baicalin therapy was associated with diminished adipose tissue content and increased mitochondrial biogenesis. Hepatic lipid accumulation and glucose output were also decreased as a result of baicalin supplementation. The molecular mechanism of the anti-diabetic action of this compound is pleiotropic and is associated with changes in the expression/action of pivotal enzymes and signaling molecules. Baicalin positively affected, among others, the tissue insulin receptor, glucose transporter, AMP-activated protein kinase, protein kinase B, carnitine palmitoyltransferase, acetyl-CoA carboxylase, and fatty acid synthase. Moreover, this compound ameliorated diabetes-related oxidative and inflammatory stress and reduced epigenetic modifications. Importantly, baicalin supplementation at the effective doses did not induce any side effects. Results of rodent studies imply that baicalin may be tested as an anti-diabetic agent in humans.

Small-molecule inhibitors targeting apoptosis signal-regulated kinase 1

Apoptosis signal regulated kinase 1 (ASK1, also known as MAP3K5) is a member of the mitogen activated protein kinase kinase kinase (MAP3K) family. Since its first isolation from a human macrophage library in 1996, its research has been ongoing for over 25 years. A large number of reports have revealed that ASK1, as a key activator of the p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK) signaling cascade, responds to various stressors, and its inhibitors have important potential value in the treatment of diseases such as inflammation, cancer, and the nervous system and so on. This review summarizes the recent development in this field, including the structure and signaling pathways of ASK1, with a particular focus on the structure-activity relationships, and the hit-to-lead optimization strategies.

A systematic review of preclinical studies exploring the role of insulin signalling in executive function and memory

Beside its involvement in somatic dysfunctions, altered insulin signalling constitutes a risk factor for the development of mental disorders like Alzheimer's disease and obsessive-compulsive disorder. While insulin-related somatic and mental disorders are often comorbid, the fundamental mechanisms underlying this association are still elusive. Studies conducted in rodent models appear well suited to help decipher these mechanisms. Specifically, these models are apt to prospective studies in which causative mechanisms can be manipulated via multiple tools (e.g., genetically engineered models and environmental interventions), and experimentally dissociated to control for potential confounding factors. Here, we provide a narrative synthesis of preclinical studies investigating the association between hyperglycaemia - as a proxy of insulin-related metabolic dysfunctions - and impairments in working and spatial memory, and attention. Ultimately, this review will advance our knowledge on the role of glucose metabolism in the comorbidity between somatic and mental illnesses.

Melatonin and probiotic administration ameliorated hyperglycaemia, oxidative stress, and enhanced cytoprotective effect on beta-cells of diabetic rats

Objective

The study aimed at investigating the effects of administering melatonin and a probiotic to streptozotocin-induced diabetic rats on hyperglycaemia, oxidative stress biomarkers and beta-cells.

Design

Type 1 diabetes was induced in 5 months-old male Wistar rats by single intraperitoneal (i.p.) administration of freshly-prepared STZ (60 mg/kg body weight). Six groups of 10 rats were used and treated once daily for six weeks; (1) Healthy control: normal saline only; (2) Pre-treated with Melatonin (MEL); (3) Diabetic control; (4) Diabetic + Treated with MEL; (5) Diabetic + Treated with Probiotic (Prob); (6) Diabetic + Treated with MEL + Prob. Blood glucose, body weight, activities of antioxidant enzymes and malondialdehyde concentration in serum and tissues, reduced glutathione and immunohistochemical assay. Data obtained were expressed as mean ± standard error of the mean (Mean ± SEM) and subjected to ANOVA followed by Tukey's post hoc test.

Results

Melatonin + Probiotic significantly decreased blood glucose concentrations in diabetic treated rats, compared to the diabetic control rats. MEL + Probiotic increased (p < 0.05) superoxide dismutase activity in serum and liver of diabetic rats. MEL + Probiotic reduced (p < 0.05) malondialdehyde concentration in the serum, liver and kidneys, respectively. MEL + Probiotic treated diabetic rats displayed islets with much greater content of insulin.

Conclusion

Melatonin + Probiotic combination was more effective in mitigating hyperglycaemia, oxidative stress, and exerted cytoprotective effect on the beta-cells.

The effect of hyperglycemia on the activation of peritoneal macrophages of albino rats

Hyperglycemia is one of the main damaging factors of diabetes mellitus (DM). The severity of this disease is most clearly manifested under conditions of the inflammatory process. In this work, we have studied the activation features of rat peritoneal macrophages (MPs) under conditions of high glucose concentration in vitro. Comparison of the independent and combined effects of streptozotocin-induced DM and hyperglycemia on proliferation and accumulation of nitrites in the MPs culture medium revealed similarity of their effects. Elevated glucose levels and, to a lesser extent, DM decreased basal proliferation and NO production by MPs in vitro. The use of the protein kinase C (PKC) activator, phorbol ester (PMA), abolished the proinflammatory effect of thrombin on PMs. This suggests the involvement of PKC in the effects of the protease. At the same time, the effect of thrombin on the level of nitrites in the culture medium demonstrates a pronounced dose-dependence, which was not recognized during evaluation of proliferation. Proinflammatory activation of MPs is potentiated by hyperglycemia, one of the main pathological factors of diabetes. Despite the fact that high concentrations of glucose have a significant effect on proliferation and NO production, no statistically significant differences were found between the responses of MPs obtained from healthy animals and from animals with streptozotocin-induced DM. This ratio was observed for all parameters studied in the work, during analysis of cell proliferation and measurement of nitrites in the culture medium. Thus, the results obtained indicate the leading role of elevated glucose levels in the regulation of MPs activation, which is comparable to the effect of DM and even "masks" it.

Animal models for induction of diabetes and its complications

Objectives

Animal models are widely used to develop newer drugs for treatment of diabetes and its complications. We conducted a systematic review to find various animal models to induce diabetes and also the suitable methods in various diabetic complications. With an emphasis on the animal models of diabetes induction, this review provides a basic overview of diabetes and its various types. It focused on the use of rats and mice for chemical, spontaneous, surgical, genetic, viral, and hormonal induction approaches.

Methods

All observations and research conducted on Diabetes and its complications published up to 18 May 2023 in PubMed, Web of Science, Scopus and Conchrane Library databases were included. Main outcome measures were reporting the induction of diabetes in experimental animals, the various animal models for diabetic complications including diabetic nephropathy, diabetic retinopathy, diabetic neuropathy and diabetic osteopathy. The quality of reporting of included articles and risk of bias were assessed.

Results

We reached various articles and found that rats and mice are the most frequently used animals for inducing diabetes. Chemical induction is the most commonly used followed by spontaneous and surgical methods. With slight modification various breeds and species are developed to study and induce specific complications on eyes, kidneys, neurons and bones.

Conclusions

Our review suggested that rats and mice are the most suitable animals. Furthermore, chemical induction is the method frequently used by experimenters. Moreover, high quality studies are required to find the suitable methods for diabetic complications.

Flavonols as a Potential Pharmacological Intervention for Alleviating Cognitive Decline in Diabetes: Evidence from Preclinical Studies

Diabetes mellitus is a complex metabolic disease associated with reduced synaptic plasticity, atrophy of the hippocampus, and cognitive decline. Cognitive impairment results from several pathological mechanisms, including increased levels of advanced glycation end products (AGEs) and their receptors, prolonged oxidative stress and impaired activity of endogenous mechanisms of antioxidant defense, neuroinflammation driven by the nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), decreased expression of brain-derived neurotrophic factor (BDNF), and disturbance of signaling pathways involved in neuronal survival and cognitive functioning. There is increasing evidence that dietary interventions can reduce the risk of various diabetic complications. In this context, flavonols, a highly abundant class of flavonoids in the human diet, are appreciated as a potential pharmacological intervention against cognitive decline in diabetes. In preclinical studies, flavonols have shown neuroprotective, antioxidative, anti-inflammatory, and memory-enhancing properties based on their ability to regulate glucose levels, attenuate oxidative stress and inflammation, promote the expression of neurotrophic factors, and regulate signaling pathways. The present review gives an overview of the molecular mechanisms involved in diabetes-induced cognitive dysfunctions and the results of preclinical studies showing that flavonols have the ability to alleviate cognitive impairment. Although the results from animal studies are promising, clinical and epidemiological studies are still needed to advance our knowledge on the potential of flavonols to improve cognitive decline in diabetic patients.

Okra [Abelmoschus esculentus (L.) Moench] improved blood glucose and restored histopathological alterations in splenic tissues in a rat model with streptozotocin-induced type 1 diabetes through CD8+ T cells and NF-kβ expression

Diabetes mellitus is a complex metabolic syndrome that involves dysfunction of spleen and other lymphoid organs. Medicinal plants, including okra (Abelmoschus esculentus (L.) Moench), were used widely for diabetes treatment. Scarce data are available about the potential anti-diabetic effects of okra, the histopathological alterations in splenic tissues and the mechanistic pathways underlying this association. The current research investigated the effects of okra pod extract on the biochemical parameters and expression of CD8+ T cells and nuclear factor kappa (NF-k) B and releasing proinflammatory cytokines in spleen in streptozotocin (STZ)-induced diabetic rat models. A total of 50 mature male Wister albino rats were divided into five isolated groups; the first served as control (untreated) animals, the second (DM group) diabetes induced by STZ (at a dose of 45 mg/kg body weight, administered intraperitoneally), the third group (DM + Insulin): diabetic rats administered insulin subcutaneously (10 units/kg bw/day) daily for 4 weeks, the fourth group was administrated 400 mg/kg okra extract daily for 4 weeks, and diabetic induced rats in the fifth group were administrated 400 mg/kg okra extract daily for 4 weeks. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity in Abelmoschus esculentus (L.) Moench was studied, and the content of phenolic compounds in okra pods was estimated using high-performance liquid chromatography. Diabetes induction led to decreased body weight, increased blood glucose levels. Capsular thickness was significantly increased, white pulp was widely dispersed, and mature lymphocytes in the periphery were also drastically decreased, with thick follicular arteries, necrosis, and depletion of lymphocytes in the germinal center. Red pulp revealed severe congestion and degenerative changes, deposition of hemosiderin granules and lymphocytic depletion. In addition, collagen fiber deposition was increased also in this group. The induction of diabetes exaggerated NF-kβ expression and mediated downregulation of the expression of CD8+ T cells in spleen tissue. Interestingly, oral administration of okra extracts post diabetes induction could mitigate and reverse such adverse effects. Altogether, our study points out the potential benefits of okra in improving blood glucose levels and restoring histopathological alterations in splenic tissues through CD8+ T cells and NF-kβ expression in a diabetic rat model.

Roflumilast ameliorates diabetic nephropathy in rats through down-regulation of JAK/STAT signaling pathway

Roflumilast is a potent selective inhibitor of the phosphodiesterase-4 enzyme which greatly manifest an anti-inflammatory activity in chronic obstructive pulmonary patients. Inflammation is a prominent factor in the prevalence of diabetic nephropathy, one of the most prevalent microvascular complications of Diabetes Mellitus. The present study was undertaken to assess the potential role of roflumilast in diabetic nephropathy. The model was developed by feeding a high-fat diet for four weeks and following streptozotocin (30 mg/kg) injection intraperitoneally. The rats with > 13.8 mmol/L blood glucose were treated with roflumilast (0.25, 0.5, 1 mg/kg) and standard metformin (100 mg/kg) orally once a day for eight weeks. Roflumilast (1 mg/kg) remarkably improved renal damage, indicated by an increase in 16% albumin, a decrease in 5% serum creatinine, 12% BUN, 19% HbA1c, and 34% blood glucose. It also significantly improves the oxidative stress levels, which was indicated by a decrease in 18% MDA level and an increase in GSH, SOD, and catalase by 6%, 4%, and 5%, respectively. In addition, Roflumilast (1 mg/kg) decreased the HOMA-IR index by 28% and increased the pancreatic β-cells functioning by 30%. Moreover, significant improvement in histopathological abnormalities were observed in roflumilast treatment groups. Roflumilast treatment was shown to down-regulate the gene expressions of TNF-α (2.1-fold), NF-kB (2.3-fold), MCP-1 (2.5-fold), fibronectin (2.7-fold), collagen IV (2.7-fold), STAT 1(1.06-fold), and STAT 3 (1.20-fold) and upregulated the expression of the Nrf2 (1.43-fold) gene. Roflumilast manifested a potential role in diabetic nephropathy as a renoprotective agent. Roflumilast effectively down-regulates the JAK/STAT pathway and restores renal functions.

Inhibition of hyaluronan synthesis prevents β-cell loss in obesity-associated type 2 diabetes

Pancreatic β-cell dysfunction and death are central to the pathogenesis of type 2 diabetes (T2D). We identified a novel role for the inflammatory extracellular matrix polymer hyaluronan (HA) in this pathophysiology. Low concentrations of HA were present in healthy pancreatic islets. However, HA substantially accumulated in cadaveric islets of T2D patients and islets of the db/db mouse model of T2D in response to hyperglycemia. Treatment with 4-methylumbelliferone (4-MU), an inhibitor of HA synthesis, or the deletion of the main HA receptor CD44, preserved glycemic control and insulin concentrations in db/db mice despite ongoing weight gain, indicating a critical role for this pathway in T2D pathogenesis. 4-MU treatment and the deletion of CD44 likewise preserved glycemic control in other settings of β-cell injury including streptozotocin treatment and islet transplantation. Mechanistically, we found that 4-MU increased the expression of the apoptosis inhibitor survivin, a downstream transcriptional target of CD44 dependent on HA/CD44 signaling, on β-cells such that caspase 3 activation did not result in β-cell apoptosis. These data indicated a role for HA accumulation in diabetes pathogenesis and suggested that it may be a viable target to ameliorate β-cell loss in T2D. These data are particularly exciting, because 4-MU is already an approved drug (also known as hymecromone), which could accelerate translation of these findings to clinical studies.

Gastroprotective evaluation of Medicago sativa L. (Fabaceae) on diabetic rats

Traditional uses for the plant Medicago sativa (M. sativa) (Alfalfa) (Family: Fabaceae) include liver protection, antioxidant activity, and the treatment of bleeding and digestive issues. This study aims to assess the effect of ethanol extract of M. sativa (EEMS) on experimental-induced ulcers in diabetic rats. By pylorus ligation and ethanol administration, gastric ulcers were induced in diabetic rats. Five groups each consisting of six rats in each model were used. All other groups except Group I were made diabetic by giving rats alloxan (140 mg/kg i.p.). Vehicles were given to Group I (normal control) and Group II (diabetes control) rats. Group III (positive control) received ranitidine 50 mg/kg, and Group IV and V received EEMS at doses of 100 and 400 mg/kg, respectively. In the pylorus ligation and ethanol-induced stomach ulcer model of rats, the findings demonstrated that EEMS (100 mg/kg) showed a decreased ulcer index of 2.01 ± 0.41 and was found statistically significant against the diabetes control group (p < 0.001) as well as, an ulcer index of 0.68 ± 0.22 by EEMS (400 mg/kg) with a significant reduction in the ulcer index (p < 0.001). EEMS (100 and 400 mg/kg) reduce free acidity by 13.16 ± 0.65 mEq/L and 9.83 ± 0.30 mEq/L, respectively. EEMS also showed a protective impact on the liver and kidneys of diabetic rats. Antihyperglycemic action was also discovered in diabetic animals. The findings of the current investigation demonstrated that ethanolic extract of M. sativa possesses anti-ulcer activity in diabetic rats. Ethanolic extract of M. sativa may be a treatment option for stomach ulcers that also have diabetes.

Protective effect of eriodictyol against hyperglycemia-induced diabetic nephropathy in rats entails antioxidant and anti-inflammatory effects mediated by activating Nrf2

The pathogenesis of diabetic nephropathy (DN) involves cellular activation of oxidative stress and inflammation. Eriodictyol is a citrus-derived flavonoid with multiple pharmacological and protective effects in various conditions. The protective role of Eriodictyol against diabetes and diabetic nephropathy is less investigated. The current research aimed to explore the role of eriodictyol in protecting against DN prompted by streptozotocin in male rats and investigate some possible mechanisms of action. Diabetes was brought about in rats by an i.p injection of a lone dose (65 mg/kg). Five groups of rats were included (n = 8 each) as control (non-diabetic), eriodictyol (20 mg/kg, orally), STZ-diabetic, STZ + eriodictyol (20 mg/kg, orally), and STZ + eriodictyol (20 mg/kg, orally) + ML385 (30 µg/kg, i.p.). Kidney histology and the levels of some markers of kidney function, renal oxidative stress, and renal inflammation were analyzed in all groups of rats. Treatment with eriodictyol prevented the damage in the renal glomeruli and tubules and reduced renal immune cell infiltration in STZ-treated animals. It also spiked urinary creatinine excretion and reduced urine volume and urinary levels of albumin, monocyte chemoattractant protein 1 (MCP-1), urinary kidney injury molecule-1 (KIM-1), and nephrin in these diabetic rats. In addition, eriodictyol stimulated the nuclear protein accumulation of Nrf2 and boosted the expression of superoxide dismutase (SOD), glutathione (GSH), heme oxygenase-1 (HO-1), and catalase (CAT) in the diabetic rat kidneys. In concomitance, it reduced the nuclear levels of NF-κB and levels of interleukine-6 (IL-6), malondialdehyde (MDA), and tumor necrosis factor-α (TNF-α) and attenuated the reduction in renal ATP levels and the increase in the mitochondria transition pore opening (mtTPT). However, the administration of eriodictyol did not affect rats' body weights and fasting glucose and insulin levels but significantly reduced serum levels of cholesterol, triglycerides, LDL-c, and oxidized LDL-c (ox-LDL-c). In conclusion, eriodictyol prevents STZ-induced nephropathy by a hypolipidemic effect and concomitant antioxidant and anti-inflammatory effects mediated by activating Nrf2/NF-κB/antioxidant axis.

EDEM1 regulates the insulin mRNA level by inhibiting the endoplasmic reticulum stress-induced IRE1/JNK/c-Jun pathway

Pancreatic beta cells produce and secrete insulin as a response to rises in blood glucose. Despite the advances in understanding glucose-regulated insulin transcription and translation the mechanisms triggering the synthesis of new insulin molecules are still incompletely described. In this report, we identify EDEM1 as a new modulator of insulin synthesis and secretion. In the presence of EDEM1, INS-1E cells secrete significantly more insulin upon glucose stimulation compared to control cells. We found that overexpression of EDEM1 inhibited the IRE1/JNK/c-Jun pathway, leading to an increase in the insulin mRNA level. Similarly, EDEM1 transduced human islets secreted significantly more insulin upon stimulation. Furthermore, EDEM1 improved insulin secretion restoring normoglycemia and glucose tolerance in diabetic rats. We propose EDEM1 as a regulator of the UPR via IRE1/XBP1s and IRE1/JNK/c-Jun signaling cascades and insulin transcription in pancreatic β-cells, supporting EDEM1 as a potential target for the treatment of diabetes.

Expression of TNFR1, VEGFA, CD147 and MCT1 as early biomarkers of diabetes complications and the impact of aging on this profile

Hyperglycemia leads to microvascular lesions in various tissues. In diabetic nephropathy-DN, alterations in usual markers reflect an already installed disease. The study of new biomarkers for the early detection of diabetic complications can bring new prevention perspectives. Rats were divided into diabetic adult-DMA-or elderly-DME and control sham adult-CSA-or control sham elderly-CSE. Blood and urine samples were collected for biochemical analysis. Bulbar region, cardiac, hepatic and renal tissues were collected for target gene expression studies. As result, DMA showed decreased TNFR1, MCT1 and CD147 expression in the bulbar region, TNFR1 in the heart, VEGFA and CD147 in the kidney and TNFR1 in blood. Positive correlations were found between TNFR1 and MCT1 in the bulbar region and HbA1c and plasma creatinine, respectively. DME showed positive correlation in the bulbar region between TNFR1 and glycemia, in addition to negative correlations between CD147 in the heart versus glycemia and urea. We concluded that the initial hyperglycemic stimulus already promotes changes in the expression of genes involved in the inflammatory and metabolic pathways, and aging alters this profile. These changes prior to the onset of diseases such as DN, show that they have potential for early biomarkers studies.

Animal Models in Diabetic Research-History, Presence, and Future Perspectives

Diabetes mellitus (DM) is a very serious disease, the incidence of which has been increasing worldwide. The beginning of diabetic research can be traced back to the 17th century. Since then, animals have been experimented on for diabetic research. However, the greatest development of diabetes research occurred in the second half of the last century, along with the development of laboratory techniques. Information obtained by monitoring patients and animal models led to the finding that there are several types of DM that differ significantly from each other in the causes of the onset and course of the disease. Through different types of animal models, researchers have studied the pathophysiology of all types of diabetic conditions and discovered suitable methods for therapy. Interestingly, despite the unquestionable success in understanding DM through animal models, we did not fully succeed in transferring the data obtained from animal models to human clinical research. On the contrary, we have observed that the chances of drug failure in human clinical trials are very high. In this review, we will summarize the history and presence of animal models in the research of DM over the last hundred years. Furthermore, we have summarized the new methodological approaches, such as "organ-on-chip," that have the potential to screen the newly discovered drugs for human clinical trials and advance the level of knowledge about diabetes, as well as its therapy, towards a personalized approach.