Role of Orexin in Obese Patients in the Intensive Care Unit

Messina G

doi:10.4172/2155-6148.1000395

Abstract

Understanding the regulation of appetite and energy expenditure mechanisms is essential for the health and disease. The recognition that the distribution of these regulatory mechanisms plays a central role in the pathogenesis of obesity and associated metabolic syndrome is not new, and it is even more interesting to understand what happens in an obese patient in the Intensive Care Unit (ICU). This review focuses on the catabolic role of orexin, which paradoxically coexists with its anabolic feeding-inducing role. The goal of this review is to provide insight into the biological mechanism governing orexin’s role in energy expenditure, discuss its significance in the context of ICU. Mammals possess a specialized tissue termed Brown Adipose Tissue (BAT) that expends calories to counteract hypothermia. The ability to enhance energy expenditure by manipulating BAT activity is attractive from a therapeutic standpoint, in light of the discovery of metabolically active BAT in adult humans. The finding of a relationship between BAT and orexins levels suggests new research on the possible roles of orexins in many anomalies of energy expenditure, including those of obese patients in the ICU.

Highlights

Understanding the regulation of appetite and energy expenditure mechanisms is essential for the health and disease
The most recent data published in the 2005– 2006 update of the National Health and Nutrition Examination Survey (NHANES) suggest that obesity rates have stabilized, others project that the obesity ‘epidemic’ will only continue to worsen, with as many as 75% of Americans and of Europeans potentially being overweight in the year 2020 [12]
Some investigators found that obese individuals had higher mortality during critical illness [13,14], whereas Ray et al [15] reported that BMI has minimal effects on Intensive Care Unit (ICU) outcome after patients are admitted to a critical care unit

Summary

Introduction

Understanding the regulation of appetite and energy expenditure mechanisms is essential for the health and disease. Coinciding with its increasing prevalence in the general population, the number of obese patients in the intensive care unit (ICU) has steadily increased over the years. Some investigators found that obese individuals had higher mortality during critical illness [13,14], whereas Ray et al [15] reported that BMI has minimal effects on ICU outcome after patients are admitted to a critical care unit.

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Conclusion