THE DIFFERENTIAL ROLE OF IRISIN: A NOVEL MYOKINE; ON INSULIN SENSITIVITY & LEARNING CAPACITY IN EXERCISED INDUCED DIABETIC RATS

Abstract

Background, Type 2 diabetes mellitus is a global health problem which still needs to be solved. Irisin, an exercise induced myokine, may have broad implications on metabolism and energy homeostasis. The aim of this work was to investigate irisin expression and its receptor and the signaling pathway in relation to cognitive functions to allow a better understanding of its role in exercised diabetic model. Methods, Forty adult male albino rats were divided equally into four groups as follows: (1) control group, (2) diabetic sedentary group, (3) Chronic exercised diabetic group, (4) Acute exercised diabetic group. Cognitive functions were assessed in all groups in T-maze. After scarification, gastrocnemius muscles, whole brains, and abdominal adipose tissues were excised for measurement of gene expression of; muscle irisin, brain irisin receptors, brain derived neurotrophic factor (BDNF) and adipose tissue uncoupling protein 1 (UCP1). In addition MAPK acitivity in brain and adipose tissue were measured. Results, Muscle irisin expression was significantly elevated in chronic and acute exercised diabetic rats compared to diabetic sedentary rats. Significant positive correlations existed between muscle irisin mRNA expression patterns versus brain irisin receptor expression, BDNF, brain MAPK activity as well as cognitive performance together with improvement in insulin sensitivity and lipid profile. On the other hand, although, muscle irisin was correlated positively with adipose MAPK activity, it was negatively correlated with adipose UCP1. Conclusions, Our results suggested that raised muscle irisin levels