Unstable Hunger Hormone Levels During Infancy Linked To Adult Obesity

Asher Bayot

There's been an alarming rise in the number of people suffering from obesity, and because of this, various studies have been finding ways to better understand the mechanisms of different hormones influencing the development of weight gain and obesity. A study, recently reported by Science Daily, sheds light on this issue through researcher Sebastien G. Bouret, PhD and his colleagues from Children's Hospital Los Angeles.

Two hormones have been found to have a major influence on energy stability of the body. Leptin acts as a mediator in energy balance that suppresses food intake, thereby inducing weight loss. Ghrelin, on the other hand, is a fast-acting hormone that plays a role in meal instigation. Ghrelin is responsible for stimulating hunger, and is the "go" hormone that tells you when to eat. It has already been established that patients with obesity are leptin-resistant. This gave researchers reason to focus on the hormone ghrelin.

The results of their study show that unstable levels of the hormone ghrelin in infants may increase lifelong obesity risks by influencing certain regions of the hypothalamus (arcuate nucleus of the hypothalamus (ARH) ventromedial hypothalamic (VMH) and the paraventricular hypothalamic (PVH) nuclei) involved in appetite and metabolism.

"We show that reduced ghrelin action results in enhanced densities of ARH neural projections during early postnatal life," Bouret and colleagues wrote. "In contrast, abnormally elevated levels of ghrelin permanently disrupt normal development of ARH neural projections."

In the January issue of the Journal of Clinical Investigation, the researchers wrote that in mouse studies, ghrelin hormone exerted "profound organizational effects" on neural projections of the arcuate nucleus of the hypothalamus (ARH) during the early postnatal period.

The researchers conducted two types of experiments in mice. In the first experiment, they blocked the ghrelin hormone soon after birth, which resulted in more axonal projections in the ARH and led to lifelong metabolic disturbances, such as obesity and diabetes. For the second experiment, scientists increased ghrelin levels during the mice's early postnatal life -- a key developmental period -- and found that it impaired the normal growth of arcuate projections and caused metabolic dysfunctions.

"Our study underlines the importance of maintaining a healthy hormonal balance -- including ghrelin -- during early life, to ensure proper development of brain-feeding centers," said Bouret

In one written press statement, Bouret stated, "A better understanding of the relationship between ghrelin levels early in life and the development of disorders such as Prader-Willi syndrome or childhood obesity will be crucial as we seek to develop interventional studies to treat and, hopefully, reverse symptoms of metabolic diseases."

The results of the study have led researchers to come up with possible interventional weight-loss strategies and appetite control mechanisms for metabolic disorders. The researchers suggest that early intervention in younger children may lower obesity risks.

[Image from Amelie/Flickr]