Intracerebroventricular administration of conjugated linoleic acid (CLA) inhibits food intake by decreasing gene expression of NPY and AgRP

Dietary conjugated linoleic acid (CLA) has been investigated for its beneficial effects on disease prevention and treatment, and now obesity is one of the most perspective researching highlights. In a variety of experimental models, the results of studies on the effects of CLA on food intakes are somewhat inconsistent. Our experiment was conducted to extend these observations to hypothalamus and other regions within the central nervous system so that the mechanism of the actions of CLA might be more easily elucidated. In the experiment, a permanent cannula was inserted into the lateral ventricle of each rat. For the experiment, animals received intracerebroventricular injections of either 150nmol (n= 16) CLA, or LA as non-conjugated control, or normal saline as vehicle. Hypothalamus and blood samples were collected at the 2nd, 4th, 8th, and 14th day. The results show that CLA in cerebral ventricle can inhibit food intake of experimented rats and this inhibition is related with the decreased expression of neuropeptides Y (NPY) and agouti-related protein (AgRP). The circulating leptin level was also increased by this tentative treatment (2.94 +/- 0.71 versus 1.18 +/- 0.18 ng/ml). However, the glucose metabolism was not affected by ICV CLA. It is concluded that CLA in brain can inhibit the appetite of rats through the mechanism of decreasing the expression of NPY and AgRP. (C) 2007 Elsevier Ireland Ltd. All rights reserved.