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Journal of Obesity
Volume 2013 (2013), Article ID 764742, 11 pages
http://dx.doi.org/10.1155/2013/764742
Research Article

Alterations in Phosphorylated CREB Expression in Different Brain Regions following Short- and Long-Term Morphine Exposure: Relationship to Food Intake

1Division of Endocrinology, Metabolism and Molecular Medicine, Department of Medicine, Charles R. Drew University of Medicine and Science and UCLA School of Medicine, 1731 E. 120th. Street, Los Angeles, CA 90059, USA
2Department of Pediatrics, Children's Hospital of Los Angeles, University of Southern California, Los Angeles, CA 90027, USA
3College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766, USA

Received 20 June 2013; Accepted 19 July 2013

Academic Editor: Yvon Chagnon

Copyright © 2013 Xiuhai Ren et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Activation of the cyclic adenosine monophosphate (cAMP)/phosphorylated CREB (P-CREB) system in different brain regions has been implicated in mediating opioid tolerance and dependence, while alteration of this system in the lateral hypothalamus (LH) has been suggested to have a role in food intake and body weight. Methods. Given that opioids regulate food intake, we measured P-CREB in different brain regions in mice exposed to morphine treatments designed to induce different degrees of tolerance and dependence. Results. We found that a single morphine injection or daily morphine injections for 8 days did not influence P-CREB levels, while the escalating dose of morphine regimen raised P-CREB levels only in the ventral tegmental area (VTA). Chronic morphine pellet implantation for 7 days raised P-CREB levels in the LH, VTA, and dorsomedial nucleus of the hypothalamus (DM) but not in the nucleus accumbens and amygdala. Increased P-CREB levels in LH, VTA, and DM following 7-day treatment with morphine pellets and increased P-CREB levels in the VTA following escalating doses of morphine were associated with decreased food intake and body weight. Conclusion. The morphine regulation of P-CREB may explain some of the physiological sequelae of opioid exposure including altered food intake and body weight.