FEATURES OF CYTOKINE PROFILE OF BLOOD IN RATS WITH STREPTOZOTOCIN-INDUCED DIABETES

Abstract

In the pathogenesis of many diseases, including diabetes mellitus, cytokines play a crucial role. It is known that cytokines are the regulators of intercellular and intersystem interactions, ensuring the consistency of the actions of the endocrine, immune, and nervous systems under standard conditions and in response to pathogenetic factors, and are involved in the development of autoimmune processes. It was established that proinflammatory cytokines, namely tumor necrosis factor-alpha, interleukin-1β, and interleukin-6 play a significant role in the loss of insulin-producing function by beta cells of the islets of Langerhans, as well as are implicated in the formation of insulin resistance in peripheral tissues.
 The aim is to study the dynamics of the content of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) in the blood serum of rats with streptozotocin-induced diabetes.
 Materials and methods The experiments were performed on 88 white male Wistar rats weighing 170–210 g, which were kept on a standard diet with free access to water. Animals were divided into three groups: 1 – intact (n=10); 2 – control (n=40); 3 – experimental (n=38) with a model of diabetes mellitus, which was reproduced by intraperitoneal injection of streptozotocin by "Sigma" company (USA), diluted in 0.1 M citrate buffer with a pH of 4.5, at a rate of 60 mg/kg body weight. The control group of animals received an intraperitoneal injection with an equivalent dose of 0.1 M citrate buffer solution with a pH of 4.5. Serum levels of TNF-α, IL-1β, and IL-6 were determined by rat enzyme-linked immunosorbent assay Rat ELISA Kits (Elabscience, USA) according to the manufacturer's instructions 14, 28, 42 and 70 days after streptozotocin injection. To assess the reliability of data changes in dynamics (14, 28, 42, 70 days) within each of the comparison groups, a non-parametric method was used (for three or more comparison groups) - Friedman's analysis of variance and Kendall's coefficient of concordance (Friedman ANOVA and Kendall's W).
 Results Conducted biochemical studies of blood serum showed that in animals with streptozotocin-induced diabetes, there was an increase in the content of proinflammatory cytokines at all stages of the experiment. In particular, TNF-α increased by 11.8% in 14 days, 34.4% in 28 days, 59.1% in 42 days and 80.1% in 70 days after the start of the experiment. An increase in the level of IL-1β was observed in the blood serum at the same time. In 14 days, the content of this cytokine increased by 22.5%, in 28 days increased by 40.2%, in 42 days increased by 72.8%, in 70 days increased by 107.2%. Along with this, we also observed an increase in the activity of IL-6 levels. In 14 days, in the blood serum, the IL-6 level was increased by 17.5%, in 28 days by 33.2%, in 42 days by 60.6% and after 70 days by 94.9% compared to the control group of animals. The analysis of the dynamics of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 in blood serum under conditions of experimental diabetes indicates their unidirectional changes.
 Conclusions The conducted studies showed that pro-inflammatory cytokines play a leading role in the pathogenesis of diabetes mellitus: TNF-α, IL-1β, and IL-6, which is indicated by a significant increase in the levels of such cytokines in blood serum at all stages of the experiment. The most pronounced changes in pro-inflammatory cytokines levels are observed at 70-day.