a1 Laboratorio de Canabinoides, Grupo de Neurociencias, Departamento de Fisiología, Facultad de Medicina, UNAM, Mexico
The central nervous system control of food intake has been extensively studied, hence, several neurotransmitter systems regulating this function are now clearly identified, for example, the endocannabinoid and serotoninergic systems. The former stimulates feeding while the latter inhibits it. Oleamide (Ole) is a cannabimimetic molecule affecting both systems. In this work, we tested the orexigenic and anorectic potential of Ole when administered into the nucleus accumbens shell (NAcS), a brain region that has been related to the orexigenic effects of cannabinoids. Additionally, we tested if Ole administered into this nucleus affects the activity of the hypothalamic nuclei involved in feeding behaviour, just as other cannabinoids do. We found a hyperphagic effect of Ole that is mediated through CB1 activation. The combination of Ole and the CB1 antagonist, AM251, produced a hypophagia that was fully blocked by SB212084, a 5-HT2C receptor antagonist. We also show that blockade of 5-HT2C and 5-HT2A receptors in the NAcS stimulates food intake. Finally, the combination of Ole and AM251 activates hypothalamic nuclei, an effect also blocked by SB242084. In conclusion, we show, for the first time, that Ole administered into the NAcS has a dual effect on feeding behaviour, acting through cannabinoid and serotonin receptors. These effects probably result from a downstream interaction with the hypothalamus.
(Received October 06 2009)
(Reviewed December 05 2009)
(Revised May 22 2010)
(Accepted May 26 2010)
(Online publication July 22 2010)
c1 Address for correspondence: Dr O. Prospéro-García, Departamento de Fisiología, Facultad de Medicina, UNAM, Apdo. Postal 70-250, México, DF, 04510, México. Tel.: (+52 55) 5623 2509 Fax: (+5255)56232395 Email: firstname.lastname@example.org