Exercise, Obesity and CNS Control of Metabolic Homeostasis: A Review

Abstract

This review details the manner in which the central nervous system regulates metabolic homeostasis in normal weight and obese rodents and humans. It includes a review of the homeostatic contributions of neurons located in the hypothalamus, the midbrain and limbic structures, the pons and the medullary area postrema, nucleus tractus solitarius, and vagus nucleus, and details how these brain regions respond to circulating levels of orexigenic hormones, such as ghrelin, and anorexigenic hormones, such as glucagon-like peptide 1 and leptin. It provides an insight as to how high intensity exercise may improve homeostatic control in overweight and obese subjects. Finally, it provides suggestions as to how further progress can be made in controlling the current pandemic of obesity and diabetes.

Can Vestibular Stimulation be Used to Treat Obesity?

“…This is the process of energy homeostasis . Nonetheless, it is well known that over the last few decades there has been a burgeoning in the proportion of people, particularly in the developed world, who are overweight or obese . In other words they are in a state skewed toward a positive energy balance; they have eaten more calories than they used, which are now stored as fat.…”

“…However, it was only in the 1990s with the discovery of the so‐called satiety hormone leptin (which leads to a reduction in appetite and feeding behavior) that attention focused on a particular area of the hypothalamus termed the arcuate nucleus (ARC) . This is because leptin binds strongly to the ARC, which is in a region with no blood brain barrier, meaning that it is fully exposed to circulating metabolic signals, such as hormones and dietary macronutrients like sugars, fats, and amino acids …”

“…[9] It is similarly well known that excess body fat is a major risk factor for a multitude of different chronic conditions, including: ischemic heart disease; stroke; type 2 diabetes mellitus; systemic hypertension; osteoarthritis; certain cancers (e.g., breast, prostate, and colon); and even cognitive decline and dementia. [4][5][6][7] As such, being obese or overweight in middle age is estimated to shorten life expectancy by 4 to 7 years. [4] It has been estimated that about $190 billion per yearthat is, 20% of total annual US healthcare expenditureis spent treating obesity and its associated conditions.…”

“…It is not widely realized that the brain, through its role in maintaining homeostasis in general, and energy homeostasis in particular, plays a major part in determining level of body fat. [5,10] It has been known since the 1940s that the hypothalamus is involved in the control of appetite. Indeed, various hypothalamic subnuclei have been implicated, via lesion studies, in both overeating and anorexia.…”

“…[10] This is because leptin binds strongly to the ARC, which is in a region with no blood brain barrier, meaning that it is fully exposed to circulating metabolic signals, such as hormones and dietary macronutrients like sugars, fats, and amino acids. [5,10] It was then elucidated that the ARC lies at the heart of what is termed the central melanocortin system, which is a group of neurons that acts to regulate energy homeostasis. This melanocortin system contains two distinct populations of neurons that act antagonistically.…”