Role of central irisin in the cardiorespiratory and metabolic control of adult rats.

Irisin has been identified as an important exercise-induced myokine that acts in different physiological systems; however, little is known about the participation of irisin in cardiorespiratory and basal metabolic control. Therefore, the present study evaluated the effect of intracerebroventricular (icv) injection of vehicle or irisin (IR, 0.425 µg/µL) in the fourth ventricle (4V) of adult male rats on the cardiorespiratory and metabolic control during wakefulness and sleep under room air, hypercapnia (7% CO ) and hypoxia (10% O ). Our data show a tendency of reduction in basal ventilation of IR group during wakefulness (VEH: 1056.2 ± 61.8 vs IR: 816.9 ± 30.5 mL.Kg .min ), due to a reduction in respiratory frequency (VEH: 105.1 ± 5.3 vs IR: 85.9 ± 5.1 breaths.min ) and a consequent decrease in arterial partial pressure of O (VEH: 95.1 ± 2.4 vs IR: 88.7 ± 3.1 mmHg). No difference was observed in metabolic rate; however, central IR promoted a reduction in the air convection requirement (VEH: 57.2 ± 4.7 vs IR: 39.6 ± 3.7). Regarding the cardiovascular parameters, central injection of IR caused a significant increase in heart rate during hypoxia exposure (VEH: 342.5 ± 38.0 vs IR: 406.2 ± 16.8 beats.min ) without changing arterial pressure. These effects were only observed in awake conditions, with no changes evidenced during sleep. No difference in cardiorespiratory and metabolic parameter were observed under CO exposure after central IR injection. Therefore, our preliminary results suggest that IR caused a hypoventilation under room air conditions, possibly due to a lower ventilation, increased heart rate under hypoxic conditions, suggesting that this myokine also acts in the central nervous system to modulate breathing and cardiovascular parameters.