FNDC5 expression and circulating irisin levels are modified by diet and hormonal conditions in hypothalamus, adipose tissue and muscle

• Published in: Scientific reports Vol. 6; no. 1; p. 29898
• Main Authors: Varela-Rodríguez, B. M., Pena-Bello, L., Juiz-Valiña, P., Vidal-Bretal, B., Cordido, F., Sangiao-Alvarellos, S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19-07-2016; Nature Publishing Group
• Subjects: 631/443/319/1642/393; 692/163/2743/348; 82/1; Adipose tissue; Adipose Tissue - metabolism; Animals; Blood; Body fat; Diabetes; Diabetes Mellitus, Experimental - blood; Diabetes Mellitus, Experimental - genetics; Diabetes Mellitus, Experimental - pathology; Diet; Fibronectins - blood; Fibronectins - genetics; Fibronectins - metabolism; Humanities and Social Sciences; Humans; Hypothalamus; Hypothalamus - metabolism; Insulin; Insulin resistance; Leptin - genetics; Leptin - metabolism; Metabolic syndrome; multidisciplinary; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; Obesity; Obesity - blood; Obesity - genetics; Obesity - pathology; Proteins; Rats; Science; Tissue Distribution - genetics
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep29898

Irisin is processed from fibronectin type III domain-containing protein 5 (FNDC5). However, a controversy exists concerning irisin origin, regulation and function. To elucidate the relationship between serum irisin and
FNDC5
mRNA expression levels, we evaluated plasma irisin levels and
FNDC5
gene expression in the hypothalamus, gastrocnemius muscle and different depots of adipose tissue in models of altered metabolism. In normal rats, blood irisin levels diminished after 48-h fast and with leptin, insulin and alloxan treatments and serum irisin concentrations increased in diabetic rats after insulin treatment and acute treatments of irisin increased blood insulin levels. No changes were observed during long-term experiments with different diets. We suggested that levels of circulating irisin are the result of the sum of the irisin produced by different depots of adipose tissue and skeletal muscle. This study shows for the first time that there are differences in
FNDC5
expression depending on white adipose tissue depots. Moreover, a considerable decrease in visceral and epididymal adipose tissue depots correlated with increased
FNDC5
mRNA expression levels, probably in an attempt to compensate the decrease that occurs in their mass. Hypothalamic
FNDC5
expression did not change for any of the tested diets but increased with leptin, insulin and metformin treatments suggesting that the regulation of central and peripheral
FNDC5
/irisin expression and functions are different.