A fat-derived protein known for its effects on the liver and skeletal muscle might also serve as an energy-conserving signal to the brain during periods of starvation, suggests a new study in the July issue of Cell Metabolism, a publication of Cell Press. The substance, known as adiponectin, acts on the brain to boost appetite and slow energy expenditure in an effort to maintain adequate fat stores during lean times, the researchers report.
Energy homeostasis may be mediated by both short-term regulators, such as gut hormones, and long-term regulators, said Takashi Kadowaki of the University of Tokyo. In this study, we identified, for the first time, a potential long-term regulator that allows energy to be stored efficiently, namely, adiponectin. The findings offer critical insight into adiponectins influence over the central nervous system and suggest that selective inhibition of the chemical in the brain may represent a novel therapeutic strategy for obesity and obesity-linked diseases, he added.
White adipose tissue (WAT) is a major site of energy storage and plays an important role in energy balance, the researchers said. It is also recognized as an important endocrine organ that secretes a number of biologically active signaling proteins, called adipokines. Adiponectin, an adipokine secreted exclusively by WAT, is present at relatively high concentrations in the circulation and has been shown to increase the bodys response to insulin. Studies have also suggested that decreased circulating levels of adiponectin in obesity and type 2 diabetes may contribute to the insulin resistance that characterizes both conditions.
In addition to its peripheral actions on the liver and skeletal muscle, adiponectin has also been reported to have central actions, Kadowaki said. Recently, however, it was reported that adiponectin is undetectable in human cerebrospinal fluid and does not cross the blood-brain barrier, leaving some doubt about its
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Cell Press
10-Jul-2007