Hypothalamic Control of Lipid Metabolism: Focus on Leptin, Ghrelin and Melanocortins

Abstract

The hypothalamus plays a crucial role in the regulation of food intake and energy expenditure. One of the main regulatory factors within the hypothalamus is AMP-activated protein kinase (AMPK), which is involved in a large number of biological actions including the modulation of energy balance. Leptin and ghrelin-induced changes in hypothalamic AMPK lead to important alterations in hypothalamic fatty acid metabolism. Furthermore, it is well known that the hypothalamus controls peripheral lipid metabolism through the sympathetic nervous system, and those actions are independent of food intake. In this short review, we highlight the main molecular pathways triggered by leptin and ghrelin altering both central and peripheral lipid metabolism and, therefore, controlling feeding behavior and energy expenditure.

Effects of monosodium-L-glutamate administration on serum levels of reproductive hormones and cholesterol, epididymal sperm reserves and testicular histomorphology of male albino rats

“…The significantly lower serum cholesterol recorded for the rats treated with MSG in this study is thought to be related to the reported damage to the arcuate nucleus of the hypothalamus in animals given MSG as the arcuate nucleus of the hypothalamus had been reported to partly function in the regulation of fat me-tabolism (Dieguez et al, 2011). This lowered serum cholesterol is believed to be partly responsible for the significantly lower serum testosterone recorded for the MSG-treated rats, as testosterone is one of the steroid hormones synthesised from cholesterol (Stocco, 1998;Hu et al, 2010).…”

Serum luteinising hormone, testosterone and total cholesterol levels, libido and testicular histomorphology of male West African Dwarf goats orally or subcutaneously treated with monosodium l-glutamate

“…However, Ahluwalia and Malik (1989) reported no effects on serum cholesterol in mice given MSG for six days. The lowering of serum cholesterol by MSG administration in this study may be attributable to the reported destructive effects of MSG on the arcuate nucleus of the hypothalamus, which is known to partly function in regulation of fat metabolism (Bazzano et al 1970;Ahluwalia and Malik 1989;Dieguez et al 2011).…”

Adipose tissue in control of metabolism

“…The satiety effect of leptin is achieved by passing the blood-brain barrier and targeting the hypothalamus, a primary hunger centre regulating food intake and body weight to regulate adipose tissue mass by decreasing food intake and modulating glucose and fat metabolism (Zhang et al 1994, Trayhurn et al 1998, Dieguez et al 2011, Morton & Schwartz 2011. In support of this, mice with deficiency of leptin expression (ob/ob) or receptor function (db/db) display increased food intake/hyperplasia, decreased energy expenditure and severe early onset obesity (Coleman 1978, Zhang et al 1994, Lee et al 1996.…”