Participation of irisin in cardiorrespiratory and metabolic control of adult rats

Author(s)

Mariana Bernardes Ribeiro

• Document type: Master's Dissertation
• Press: Jaboticabal. 2022-09-06.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2022-07-18
• Advisor: Luciane Helena Gargaglioni Batalhão

Abstract

Irisin is a newly identified hormone consisting of 112 amino acids, derived from a transmembrane protein encoded by the type III fibronectin gene containing 5 (FNDC5), which is highly related to the metabolic activity of skeletal muscle and adipose tissue, having a similarity of 100% between rats and humans. It is known that the concentration of irisin increases during physical exercise, bringing beneficial effects to various tissues, including the central nervous system, promoting neuroplasticity, since irisin seems to be associated with neural proliferation and differentiation. It has also recently been shown that this hormone modulates cardiovascular functions, possibly acting as an important messenger between organs to integrate energy expenditure with cardiovascular activity. Therefore, the present study evaluated the effect of intracerebroventricular (icv) injection of vehicle or irisin (IR, 0.425 and 1.66 µg/µL) in the fourth ventricle (4V) of adult male rats in ventilation (VE), oxygen consumption (VO2), ventilatory equivalent (VE / VO2), body temperature (TB), mean arterial pressure (MAP) and heart rate (HR) in wakefulness and sleep state during room air, hypercapnia (7% CO2) and hypoxia (10% O2). Treatment with irisin centrally with the lowest concentration (0.425 µg/µL), promoted a reduction in VE in room air conditions during wakefulness, culminating in a hypoventilation (lower VE / VO2). During exposure to room air conditions, animals treated with the highest concentration of irisin (1.66 µg/µL) also showed a reduction in VE and fR. The animals treated with the highest concentration of irisin when exposed to high levels of CO2 showed an increase in VE, due to a higher VT and a reduction in VO2, which resulted in hyperventilation (higher VE / VO2) during wakefulness. The both concentrations of irisin attenuated hypoxia-induced regulated hypothermia. Regarding cardiovascular parameters, central irisin injection with the lower concentration caused a significant increase in HR under all conditions during sleep and wakefulness, without altering MAP. The treatment with the highest concentration promoted an increase in HR in the animals when exposed to hypoxia during sleep and wakefulness states and during hypercapnia in sleep state. Our data demonstrate that irisin exerts an inhibitory effect on breathing control and potentiates the hyperventilatory response under hypercapnia, promoting an increase in VE and inhibiting VO2 during wakefulness. In addition, this myokine is excitatory to HR and attenuates the drop in body temperature in low O2 conditions. (AU)

• FAPESP's process: 20/02918-9 - Role of irisin in cardiorespiratory and metabolic control of adult rats
• Grantee: Mariana Bernardes Ribeiro
• Support Opportunities: Scholarships in Brazil - Master