Streptozotocin (STZ) (2-deoxy-2-({[methyl(nitroso)amino]carbonyl}amino)-β-D-glucopyranose) is a naturally occurring diabetogenic compound, produced by the soil bacteriumstreptomyces achromogenes, that exhibits broad spectrum of antibacterial properties. Streptozotocin functions as a DNA synthesis inhibitor in both bacterial and mammalian cells. In mammalian cells, the actual mechanism and metabolic targets of STZ toxicity that results in cell death is not known. This review identifies four key areas that explain the mechanism of the cytotoxicity of STZ in mammalian cell lines, investigates the practical aspects of using STZ in experimental animals and the potential risks of its exposure to human health.

Oxidative stress, inflammation and apoptosis are major complications that trigger organ failure in diabetes mellitus (DM), and are proven to adversely affect the male reproductive system. Clinical and experimental studies have demonstrated the promising protective effects of propolis in DM and its associated systemic effects. Herein, we investigated the effect of Malaysian propolis (MP) on testicular oxidative stress, inflammation and apoptosis in diabetic rats. Further, the possibility of a complementary effect of MP with the anti-hyperglycaemic agent, metformin (Met), was studied with the idea of recommending its use in the event that Met alone is unable to contain the negative effects of DM on the male reproductive system in mind. Male Sprague-Dawley rats were either gavaged distilled water (normoglycaemic control and diabetic control groups), MP (diabetic rats on MP), Met (diabetic rats on Met) or MP+Met (diabetic rats on MP+Met), for 4 weeks. MP decreased oxidative stress by up-regulating (p < 0.05) testicular mRNA levels of nuclear factor erythroid 2-related factor 2, superoxide dismutase, catalase and glutathione peroxidase; increasing (p < 0.05) the activities of antioxidant enzymes; and decreasing (p < 0.05) lipid peroxidation in the testes and epididymis of diabetic rats. Further, MP down-regulated (p < 0.05) testicular mRNA and protein levels of pro-inflammatory mediators (nuclear factor kappa B, inducible nitric oxide synthase, tumour necrosis factor-α and interleukin (IL)-1β), decreased (p < 0.05) the nitric oxide level, and increased (p < 0.05) IL-10 mRNA and protein levels. MP also down-regulated (p < 0.05) Bax/Bcl-2, p53, casapase-8, caspase-9 and caspase-3 genes, and increased (p < 0.05) testicular germ cell proliferation. MP’s effects were comparable to Met. However, the best results were achieved following co-administration of MP and Met. Therefore, we concluded that administration of the MP+Met combination better attenuates testicular oxidative stress, inflammation and apoptosis in DM, relative to MP or Met monotherapy, and may improve the fertility of males with DM.

The concept of low glycemic index and glycemic load foods as panacea for type 2 diabetes mellitus; prospects, challenges and solutions

Aim. To investigate the ameliorating potentials of cocoyam (Colocasia esculentaL.) and unripe plantain (Musa paradisiacaL.) incorporated feeds on the renal and liver growths of diabetic rats, induced with 55 and 65 mg/kg body weight of Streptozotocin.Method. The blood glucose level of the rats was measured with a glucometer, the protein and glucose and specific gravity (SPGR) in the urine samples of the rats were measured using urine assay strips and urinometer respectively. The chemical composition and antioxidant screening of the test feeds were carried out using standard techniques.Results. Administration of the test feeds for 21 days to the diabetic rats of groups 4 and 5, resulted in 58.75% and 38.13% decreases in hyperglycemia and amelioration of their elevated urinary protein, glucose, SPGR, and relative kidney weights. The diabetic rats administered cocoyam incorporated feeds, had 2.71% and 19.52% increases in weight and growth rates, the diabetic rats administered unripe plantain incorporated feeds had 5.12% and 29.52% decreases in weight and growth rates while the diabetic control rats had 28.69%, 29.46%, 248.9% and 250.14% decreases in weights and growth rates. The cocoyam incorporated feeds contained higher antioxidants, minerals and phytochemicals except alkaloids than unripe plantain feed.Conclusion. Cocoyam and unripe plantain could be useful in the management of diabetic nephropathy.

The ameliorating potentials of ginger incorporated feed (10%) on the relative organ weights of Streptozotocin (STZ) induced diabetic rats was investigated. The experiment lasted for three weeks. Results show that administration of 10% ginger feed to the diabetic rats of group 3, resulted in a 29.81% decrease in their resulting hyperglycemia with a corresponding amelioration of elevated urinary protein, sugars, specific gravity as well as renal growth. In addition, administration of the ginger incorporated feeds to the diabetic rats of group 3, resulted in 9.88% increase in body weight with a corresponding 60.24% increase in growth compared with the non-diabetic rats administered standard rat pellets that had 6.21% increase in weight with a corresponding 60.14% increase in growth unlike the diabetic control rats that recorded 28.62% decrease in body weight with a corresponding 239.9% decrease in growth rates. Analysis of the chemical composition of the flour of the ginger incorporated feed indicated that it contained low quantities of moisture but significant quantities of crude fibre, proteins, lipids, carbohydrates, ash, alkaloids, flavonoids, saponins, tannins, calcium, magnesium, potassium, iron, zinc, phosphorous in addition to considerable amount of energy. There was no significant difference (P>0.05) in the liver and relative liver weights of the diabetic control rats and the diabetic -ginger treated rats. In addition, there were no significant differences in the kidney weights of the non-diabetic, diabetic control and diabetic treated rats (P>0.05) and there was also no significant difference in the relative kidney weight of the non-diabetic rats and the diabetic rats treated with ginger feeds (P>0.05). Results show that the use of ginger in the dietary management of diabetes mellitus could be a breakthrough in the search for novel plants that could prevent the development of diabetic glomerular hypertrophy.