Assessment of Pharmacological Responses to an Anti-diabetic Drug in a New Obese Type 2 Diabetic Rat Model

Design, Synthesis, and Biological Evaluation of 1,4-Dihydropyridine-Indole as a Potential Antidiabetic Agent via GLUT4 Translocation Stimulation

In the quest for the discovery of antidiabetic compounds, a series of 27 1,4-dihydropyridine-indole derivatives were synthesized using a diversity approach. These compounds were systematically evaluated for their antidiabetic activity, starting with an in vitro assessment for GLUT4 translocation stimulation in L6-GLUT4myc myotubes, followed by in vivo antihyperglycemic activity evaluation in a streptozotocin (STZ)-induced diabetic rat model. Among the synthesized compounds, 12, 14, 15, 16, 19, 27, and 35 demonstrated significant potential to stimulate GLUT4 translocation in skeletal muscle cells. Compound 19 exhibited the highest potency and was selected for in vivo evaluation. A notable reduction of 21.6% (p < 0.01) in blood glucose levels was observed after 5 h of treatment with compound 19 in STZ-induced diabetic rats. Furthermore, pharmacokinetic studies affirmed that compound 19 was favorable to oral exposure with suitable pharmacological parameters. Overall, compound 19 emerged as a promising lead compound for further structural modification and optimization.

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.

Dose-dependent effects of taurine against testicular damage in a streptozotocin-induced type 1 diabetes mellitus rat model

OBJECTIVES

Testicular dysfunction has been associated with chronic hyperglycemia in diabetes mellitus patients. We investigated taurine's possible mechanisms and protective effects against testicular damage using a rat model of streptozotocin-induced diabetes.

METHODS

Wistar rats (N = 56) were divided into seven equal groups. Untreated control rats received saline, and treated control rats received taurine 50 mg/kg orally. To induce diabetes, rats received a single dose of streptozotocin. Metformin-treated diabetic rats received metformin at a dose of 300 mg/kg. Taurine-treated groups received 10, 25, or 50 mg/kg. All treatments were provided orally once a day for 9 weeks following the streptozotocin injection. Levels of blood glucose, serum insulin, cholesterol, testicular tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1beta (IL-1β), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH), and catalase (CAT) were examined. Sperm count, progressive sperm motility, and sperm abnormalities were examined. Body and relative reproductive gland weights were assessed. Histopathological examinations of the testes and epididymis were performed.

RESULTS

Metformin as well as taurine (in a dose-dependent manner) resulted in significant improvements in body and relative reproductive gland weights, blood glucose, serum cholesterol, and insulin levels, as well as cytokine and oxidative parameters. These findings were associated with significant improvement in sperm count, progressive sperm motility, sperm abnormalities, and histopathological lesions in the testes and epididymis.

CONCLUSION

Taurine can potentially improve hyperglycemia, hypercholesterolemia, and testicular damage associated with diabetes mellitus, possibly by controlling inflammation and oxidative stress.

Renoprotective effect of empagliflozin in cafeteria diet-induced insulin resistance in rats: Modulation of HMGB-1/TLR-4/NF-κB axis

AIM

Cafeteria diet (CAF) is a well-established model used to mimic what occurs in human upon eating junk and ultra-processed food. This study aimed to investigate the possible protective impact of empagliflozin (EMPA) against CAF-induced insulin resistance (IR) in rats and the possible underlying mechanisms.

MAIN METHODS

Rats were fed on CAF diet for 12 weeks while treatment with EMPA (10 & 30 mg/kg/day, orally) and/or metformin (MET) (100 mg/kg/day, orally) started at day 29.

KEY FINDINGS

Oral administration of EMPA and/or MET significantly and dose-dependently succeeded to attenuate CAF-induced obesity which was evidenced by decreased oral glucose tolerance test (AUC_OGTT), insulin tolerance test (AUC_ITT) and decreased fasting serum insulin level besides improving the histopathological alterations induced by CAF. Moreover, EMPA significantly mitigated CAF-induced elevation in serum levels of creatinine urea, transaminases (ALT and AST), and increased albumin level as well as improving dyslipidemia and oxidative stress. Furthermore, EMPA markedly reduced renal levels of high mobility group box 1 (HMGB-1), toll like receptor4 (TLR-4) and nuclear factor κB (NF-κB) as well as decreasing the expression of tumor necrosis factor α (TNF-α) and Caspase 3. Combining EMPA₃₀ with MET synergistically improved dyslipidemia, oxidative stress and enhanced kidney function.

SIGNIFICANCE

EMPA administration could confer protection against CAF-induced IR and its complications through its hypoglycemic, insulin-sensitizing, hypolipidemic, hepatoprotective, renoprotective, anti-inflammatory, anti-oxidant and anti-apoptotic properties. Also, our findings highlighted the synergistic effect of combining EMPA₃₀ with MET so this combination might be promising in treatment of IR.

Future Perspective of Diabetic Animal Models

Objective

The need of today’s research is to develop successful and reliable diabetic animal models for understanding the disease susceptibility and pathogenesis. Enormous success of animal models had already been acclaimed for identifying key genetic and environmental factors like Idd loci and effects of microorganisms including the gut microbiota. Furthermore, animal models had also helped in identifying many therapeutic targets and strategies for immune-intervention. In spite of a quite success, we have acknowledged that many of the discovered immunotherapies are working on animals and did not have a significant impact on human. Number of animal models were developed in the past to accelerate drug discovery pipeline. However, due to poor initial screening and assessment on inequivalent animal models, the percentage of drug candidates who succeeded during clinical trials was very low. Therefore, it is essential to bridge this gap between pre-clinical research and clinical trial by validating the existing animal models for consistency.

Results and Conclusion

In this review, we have discussed and evaluated the significance of animal models on behalf of published data on PUBMED. Amongst the most popular diabetic animal models, we have selected six animal models (e.g. BioBreeding rat, “LEW IDDM rat”, “Nonobese Diabetic (NOD) mouse”, “STZ RAT”, “LEPR Mouse” and “Zucker Diabetic Fatty (ZDF) rat” and ranked them as per their published literature on PUBMED. Moreover, the vision and brief imagination for developing an advanced and robust diabetic model of 21^st century was discussed with the theme of one mice-one human concept including organs-on-chips.

Evaluation of Preclinical and Clinical Studies Published in Medical Journals of Bosnia and Herzegovina: Methodology Issues

INTRODUCTION

Results of preclinical and clinical studies in medicine could be trusted only if their design and statistical analysis were appropriate.

AIM

The aim of our study was to investigate whether preclinical and clinical studies published in medical journals of Bosnia and Herzegovina satisfy basic requirements for appropriate design and statistical interpretation of data.

METHODS

Preclinical and clinical studies published in medical journals of Bosnia and Herzegovina were retrieved from the PubMed database, and the sample for analysis was randomly chosen from the retrieved publications. Implementation rate of basic principles of experimental design (local control, randomization and replication) and rate of the most common errors in design of clinical/observational studies was established by careful reading of the sampled publications and their checking against predefined criteria.

RESULTS

Our study showed that only a minority of experimental preclinical studies had basic principles of design completely implemented (7%), while implementation rate of single aspects of appropriate experimental design varied from as low as 12% to as high as 77%. Only one of the clinical/observational studies had none of the errors searched for (2%), and specific errors rates varied from 10% to 89%. Average impact factor of the surveyed studies was around one, and average publication date recent, less than 5 years ago.

CONCLUSION

Prevalence of preclinical studies that did not follow completely basic principles of research design, and that of clinical/observational studies with errors are high, raising suspicion to validity of their results. If incorrect and not protected against bias, results of published studies may adversely influence future research.

Synergistic effect of novel chitosan combined metformin drug on streptozotocin-induced diabetes mellitus rat

Metformin is widely used as a frontline medicine of type-II diabetes. Frequent overdose side-effects and their consequent adversative need to be reduced. The novel source of marine hydrozoa, Thyroscyphus ramosus derived chitosan combined metformin drug was administrated to evaluate the antidiabetic potential on a high-fat diet (HFD) with streptozotocin (STZ) induced diabetic rats. The primary analysis of In vitro antioxidant activity was tested for various solvent dissolved chitosan. Based on their IC₅₀ dose values, CsnAA was chosen for further experiments. The chitosan was combined with metformin by sonication and confirmed through XRD, FTIR and SEM analysis. The enhanced activity was observed in 100 mg/kg metformin combined with CSN500mg/kg. The level of serum bilirubin, total protein, SGH, liver glycogen, Glucose-6-phosphatase and fructose-1,6- phosphatase values were significantly similar to metformin 300 mg/kg treated group. With this beneficiary, the novel chitosan was recommended to administrate with metformin to improve the drug efficacy and reduction of overdose lethal effects.