Food restriction promotes damage reduction in rat models of type 2 diabetes mellitus.

There are several animal models of type 2 diabetes mellitus induction but the comparison between models is scarce. Food restriction generates benefits, such as reducing oxidative stress, but there are few studies on its effects on diabetes. The objective of this study is to evaluate the differences in physiological and biochemical parameters between diabetes models and their responses to food restriction. For this, 30 male Wistar rats were distributed in 3 groups (n = 10/group): control (C); diabetes with streptozotocin and cafeteria-style diet (DE); and diabetes with streptozotocin and nicotinamide (DN), all treated for two months (pre-food restriction period). Then, the 3 groups were subdivided into 6, generating the groups CC (control), CCR (control+food restriction), DEC (diabetic+standard diet), DER (diabetic+food restriction), DNC (diabetic+standard diet) and DNR (diabetic+food restriction), treated for an additional two months (food restriction period). The food restriction (FR) used was 50% of the average daily dietary intake of group C. Throughout the treatment, physiological and biochemical parameters were evaluated. At the end of the treatment, serum biochemical parameters, oxidative stress and insulin were evaluated. Both diabetic models produced hyperglycemia, polyphagia, polydipsia, insulin resistance, high fructosamine, hepatic damage and reduced insulin, although only DE presented human diabetes-like alterations, such as dyslipidemia and neuropathy symptoms. Both DEC and DNC diabetic groups presented higher levels of protein carbonyl groups associated to lower antioxidant capacity in the plasma. FR promoted improvement of glycemia in DNR, lipid profile in DER, and insulin resistance and hepatic damage in both diabetes models. FR also reduced the protein carbonyl groups of both DER and DNR diabetic groups, but the antioxidant capacity was improved only in the plasma of DER group. It is concluded that FR is beneficial for diabetes but should be used in conjunction with other therapies.

Insulin complexed with cyclodextrins stimulates epithelialization and neovascularization of skin wound healing in rats.

INTRODUCTION: Skin lesions are a significant public health problem, above all that wounds fail to heal properly and become chronic. Due to its reepithelization action, insulin has the potential to heal skin lesions, by stimulating the proliferation and migration of keratinocytes, angiogenic stimulus, and increasing collagen deposition. In the present study insulin was complexed with 2-hydroxypropyl-ß-cyclodextrin (HPßCD) and its wound healing effect and inclusion complex (HPßCD-I) were evaluated in excisional wounds in the skin of rats. MATERIAL AND METHODS: Three different gel based pharmaceutical forms were created: carbopol 940® base gel, an insulin gel comprising the base gel plus 50 IU of insulin and a gel complex comprising the base gel plus (HPßCD) complexed with insulin (HPßCD-I) were used to verify wound healing in vitro and in vivo assays. RESULTS: The wounds in the skin of rats were treated with gel containing HPßCD-I not cytoxically irritating and cytotoxic. Analysis of cell proliferation and measurement of the length and thickness of the epidermis showed that HPßCD-I prolonged the proliferation and migration of keratinocytes. Revascularization analysis of lesions treated with HPßCD-I compared to those treated with insulin found that angiogenic stimulus was less intense, but more constant and prolonged in the modified release process. There was increased deposition of type I and III collagen fibers in accordance with the treatment time. CONCLUSION: Therefore, the slow release of complexed insulin modulated the reepithelialization process by stimulating cell proliferation and migration of keratinocytes, favoring greater concentration of serum insulin, modulating inflammatory response, matrix remodeling and promoting neovascularization. Angiogenesis extended by the steady release of insulin can be effective in the treatment of chronic wounds.