AGE-RELATED CHANGES OF IRISIN LEVELS IN PLASMA AND CEREBROSPINAL FLUID OF HUMANS

Abstract

Background: Irisin, exercise-inducible myokine, is proposed to interact with other tissues, such as fat and brain to regulate the balance of metabolism, increase energy expenditure, weight loss and neurogenesis. Here, we investigated age-related changes of Irisin levels in CSF, and relationship to paired plasma and adiposity.

Methods: Irisin levels were measure in paired plasma and cerebrospinal fluid (CSF) of 77 normal human subjects (18 females and 59 males, age from 17 to 82) by ELISA assays.

Results: Using multiple linear regression analysis, we found Irisin levels in CSF and plasma gradually increased from young to high-aged stage and the levels of males were higher than that of females. Irisin levels in CSF and plasma were associated with gender and age, but not BMI. CSF Irisin levels were not associated with plasma levels. The relationship between plasma levels and CSF:plasma ratio was a quadratic curve. 19.7% of CSF:plasma ratio variance can be accounted for by plasma levels. No significant relationship between CSF:plasma ratio and age. The lowest value of CSF:plasma ratio were found in the age stage of 50–65 years old.

Conclusions: The levels of Irisin in CSF and plasma were increased with the increase of age. Males have higher Irisin levels in CSF and plasma. There is a saturable mechanism that regulates CSF irisin transport.