Abstract

Irisin is secreted as a product of fibronectin type III domain-containing protein 5 (FNDC5) from muscle cells, neurons, and other cell types in response to exercise. Numerous studies support the role of irisin in restoring energy homeostasis, optimizing cellular energy utilization, stimulating the process of browning white adipose tissue, and promoting energy expenditure. A previous study showed that 8 weeks of treadmill exercise blunts sucrose preference in Long-Evans rats. Here we hypothesized that central irisin may play a role in the suppression of sucrose preference following exercise training. Female Sprague Dawley rats (n=13) were implanted with cannulas targeting the lateral ventricle (LV). In order to optimize an intracerebroventricular (ICV) irisin dose to examine sucrose preference, we first examined the effect of ICV irisin (0, 0.50, 1.0, and 2.0 ug) on chow intake following an overnight fast. ICV irisin suppressed chow intake following all doses, thus the lowest dose was selected for the sucrose preference test. To assess taste-behavior changes, a 2-bottle preference test was employed, where 1 bottle of water and 1 bottle of 0.1 M sucrose solution were placed on each cage. Rats received ICV saline or 0.50 ug irisin 1 hour prior to the start of the 2-bottle preference test. Fluid intake was measured at 15, 120, and 240 min and at 24 and 48h after placements. At 24h, the bottles switched sides.  Preference was calculated as the proportion of sucrose intake that made up total fluid intake. Relative to vehicle treatment, irisin reduced sucrose preference at 24h. Together these effects suggest that central irisin plays a role in the control of feeding and highlights irisin as a potentially important mechanism involved in the ability of exercise to alter taste preferences.