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Sermorelin, Sleep and the Brain

“product By Logan 4 years ago

Fifteen years ago, orexins were identified as central regulators of energy homeostasis. Research indicates that orexins are key modulators of the sleep-wake cycle and that these neuropeptides also affect feelings of satiety and hunger. Given their role in energy homeostasis, it was hypothesized that orexin levels are likely regulated, at least in part, by the growth hormone axis. Recent research supports this fact and suggests that growth hormone releasing hormone analogues, such as sermorelin, may be effective in treating conditions in which orexin release is dysfunctional (e.g. narcolepsy) [1].

Understanding Orexin

The brain contains just 10,000 to 20,000 orexin (also called hypocretin) neurons, a relatively low number. Interestingly, these neurons extend throughout the entire brain and spinal cord. Additionally, there are receptors for orexins throughout the nervous system. Deficiencies of orexin have been linked to obesity (orexin stimulates fat burning) and narcolepsy while over stimulation of certain orexin receptors has been shown to cause changes in reward seeking behavior. It is hypothesized that the ability to manipulate orexin may be useful in cases of addiction, overeating, and other medical conditions. Scientific studies based on animal test subjects have shown that Sermorelin may indirectly stimulate orexin neurons and thus increase overall levels of orexin in the nervous system.

Weight Control with Sermorelin

Orexin plays a central role in the development of brown adipose tissue, a type of fatty tissue very different from white adipose tissue. Brown adipose tissue is thermogenic, which means that it acts to create heat. In fact, brown adipose tissue, when active, contributes to weight loss by simply "wasting" calories to generate heat. There is some speculation that manipulation of orexin may help to increase metabolic rates in mammals and thus promote healthy weight.

Leptin, the "satiety hormone," has been found to regulate weight by sending "full" signals to the brain of many mammals. Studies in sheep indicate that some of orexins effects may mimic those of leptin or may, in fact, be more potent than leptin [2]. Orexin depletion has also been linked to a dampening of energy expenditure in mice [3]. In short, orexin may have more impact on hunger and energy expenditure than leptin does, a fact that would fit well with existing evidence regarding the association between sleep and hunger (less sleep leads to increased hunger) as well as the fact that therapeutics targeting leptin receptors have been relatively ineffective in treating obesity.

The Summary

Because sermorelin is a growth-hormone releasing hormone GHRH) analogue, it stimulates the growth hormone axis and the multiple body processes that it influences. In the case of orexin, Sermorelin appears to have a multitude of effects. Studies in trout indicate that the use of Sermorelin and other GHRH analogues may lead to improved regulation of orexin axis and thus improved sleep, weight control, and impulse control [4].

Resources

[1] M. Álvarez-Crespo, N. Martínez-Sánchez, F. Ruíz-Pino, M. Garcia-Lavandeira, C. V. Alvarez, M. Tena-Sempere, R. Nogueiras, C. Diéguez, and M. López, "The orexigenic effect of orexin-A revisited: dependence of an intact growth hormone axis," Endocrinology, vol. 154, no. 10, pp. 3589-3598, Oct. 2013.

[2] K. Kirsz, M. Szczesna, K. Dudek, P. M. Bartlewski, and D. A. Zieba, "Influence of season and nutritional status on the direct effects of leptin, orexin-A and ghrelin on luteinizing hormone and growth hormone secretion in the ovine pituitary explant model," Domest. Anim. Endocrinol., vol. 48, pp. 69-76, Jul. 2014.

[3] D. Sellayah, P. Bharaj, and D. Sikder, "Orexin is required for brown adipose tissue development, differentiation, and function," Cell Metab., vol. 14, no. 4, pp. 478-490, Oct. 2011.

[4] B. S. Shepherd, J. K. Johnson, J. T. Silverstein, I. S. Parhar, M. M. Vijayan, A. McGuire, and G. M. Weber, "Endocrine and orexigenic actions of growth hormone secretagogues in rainbow trout (Oncorhynchus mykiss),"Comp. Biochem. Physiol. A. Mol. Integr. Physiol., vol. 146, no. 3, pp. 390-399, Mar. 2007.

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