ABSTRACT
Introduction: Adipose tissue, both white and brown, play an important role in energy homoeostasis. These tissues contain three types of adipocytes, white, brown, and beige [brown-in-white] adipocytes. The beige adipocytes of white adipose tissue, have a white fat-like phenotype and upon stimulation change to a brown fat-like phenotype, leading to increased thermogenesis, a phenomenon called browning. Obesity, a risk factor for the development of diabetes, with an increasing prevalence worldwide, depends not only on the intake-consumption ratio of calories, but also on the ratio of white-to-brown adipose tissue. Browning of white adipose tissue in humans is associated with beneficial metabolic effects. Nitric oxide deficiency contributes to the pathogenesis of obesity and diabetes. Nitric oxide is synthesized from L-arginine by nitric oxide synthase enzymes [classic pathway] and also independently from nitric oxide synthase- [nitrate-nitrite pathway]. Nitric oxide production from the nitrate-nitrite pathway could potentially be used as a nutrition-based therapy in obesity and diabetes. The aims of this review is to summarize the properties of adipose tissue browning, and also, the browning effects of the nitrate-nitrite-nitric oxide. Based on literature available, administration of nitrate and nitrite can be considered to be a new treatment for obesity and diabetes. Nitrate and nitrite increase browning of white adipocytes by increasing nitric oxide and can improve metabolism?
ABSTRACT
Cardiovascular diseases are the most important complications of diabetes, representing the ultimate cause of death in more than half of all patients with the disease. Nitrate has been demonstrated to be an effective add-on therapy in patients with heart failure but no study has been yet addressed the effect of nitrate therapy on myocardial injury associated with diabetes. The aim of this study was therefore to assess the effect of nitrate therapy on myocardial injury in type 2 diabetic rats. Thirty-two adult male Wistar rats were divided into four groups [n=8]: Control, control+nitrate, diabetes, and diabetes+nitrate. Type 2 diabetes was induced by injection of nicotinamide [95 mg/kg] 15 min before injection of streptozotocin [65 mg/kg]. Nitrate in control+nitrate and diabetes+nitrate groups was added to the drinking water [100 mg/L for 2 months]. Serum nitrate+nitrite [NOx], CK-MB, and LDH were measured before and at the end of the study and heart malonyldialdehyde [MDA] was measured at the end of the study. Nitrate therapy in diabetic rats significantly increased serum NOx levels [29.2 +/- 5.6 vs. 42.8 +/- 9.8 micromol/L, P<0.05], decreased heart MDA levels [9.7 +/- 1.2 vs. 6.2 +/- 0.6 micromol/L, P<0.05], and decreased serum levels of both CK-MB [471.0 +/- 29.7 vs. 284.9 +/- 10.3 U/L, P<0.05] and LDH [791.6 +/- 21.9 vs. 497.8 +/- 13.1 U/L, P<0.05]. Nitrate therapy provided cardioprotection by increasing NO levels and decreasing oxidative stress in type 2 diabetic rats
ABSTRACT
Human subjects can not always used as models for studying disease by researchers because of the potential risks for human health, and in addition, control of interfering factors is not easy in these subjects. Animal biology, physiology, anatomy, biochemistry, pharmacology, and genetics are very similar to humans. Animals are suitable models for research, as their functional body system is similar to humans and is easily manipulated. Most of our current knowledge in medical sciences is obtained from animal studies, among which, rats and mice are mostly used for the their shorter lifespans, which creates the possibility of producing many generations and studying total lifespan. The thyroid plays pivotal role in the body and is vital for normal function of almost all tissues throughout life. Decreased secretion of thyroid hormones from the thyroid gland [hypothyroidism] is a prevalent disorder and as a result animal models of hypothyroidism are often very important for research purposes. Thyroidectomy, genetic manipulation, and using anti-thyroid drugs are the most important ways to induce hypothyroidism in animals. The aim of this study was to review and evaluate different models for induction of hypothyroidism in rat, and in addition to compare the characteristics of rat and human thyroid glands. Anti-thyroid drugs could be used as cheap, available, and simple methods for inducing hypothyroidism, although they may also affect the function of other organs
ABSTRACT
Humans can rarely be used as experimental models in medical researches, because of ethical issues. Therefore, some animal models, which have physiological systems similar to humans, are commonly used. In this regard, rats and mice are the most favorable species in research models. The thyroid gland has a key role in human growth and development and is essential for normal functioning of the body systems and tissues. The aim of this study was to review rat and mouse models of hyperthyroidism. Related articles published between 1975-2014 on hyperthyroidism in rat and mice were searched in Pub Med. Hyperthyroidism can be induced in animals using different doses of thyroid hormons [T3 and T4] by oral administration, injection, or with the diet. In addition, transgenic mice could act as a model of hyperthyroidism for the design of specific model of hyperthyroidism, such as Graves' disease. Animal models of hyperthyroidism could be used for studying the disease, treatment and identification of the molecular mechanisms involved. Pharmacologic agents are mostly used for creating animals models of hyperthyroidism because of their easy availability and low cost, compared to genetic techniques that are costly and expensive