Ghrelin, Total ELISA Test

While Ghrelin has potent growth hormone releasing properties comparable to growth hormone releasing hormone (1), it also has powerful growth hormone independent effects (2). Administration of Ghrelin peripherally or centrally into the cerebral ventricles induces weight gain in rodents (3) and in humans, Ghrelin levels peak prior to each meal and then fall to lower levels immediately upon feeding.

In humans, circulating Ghrelin levels are decreased in acute states of positive energy balance and in chronic obesity, but elevated during fasting and in anorexia nervosa. These data further support the hypothesis that the secretion of Ghrelin not only has effects opposite to leptin, but is also regulated antipodal to leptin. Whether increased Ghrelin levels in anorexia nervosa reflect a pathophysiological state of Ghrelin resistance analogous to that of leptin resistance in obesity remains to be elucidated. In addiction, the development of a Ghrelin antagonist, or the development of a mechanism to inhibit Ghrelin release to control appetite may be an important pharmaceutical development for the management of obesity.

Finally, recent evidence suggests that Ghrelin may play a role in reproductive function, a scenario that is analogous to the elucidation of a role of leptin in the control of reproductive function (4).

1. Kojima M, et al. Nature 402: 656-660, 1999.
2. Nakazato M, et al. Nature. 409: 194-198, 2001.
3. Wren AM, et al. Endocrinology 141: 4325-4328, 2000.
4. Henson, M.C. & Castracane, V.D., eds. (2003) Leptin and Reproduction. Kluwer Academic Publishers, New York, New York.