Alterations in phosphorylated CREB expression in different brain regions following short- and long-term morphine exposure: Relationship to food intake

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. © 2013 xiuhai ren et al.