Anti-Proenkephalin B (aa 232-245) polyclonal antibody

In situ hybridization and specific radioimmunoassays were used to study the influence of ethanol on proopiomelanocortin (POMC) and prodynorphin (PDYN) biosynthesis in the rat pituitary. Repeated intragastric ethanol administration (starting with a total daily dose of 5 g/kg every 2nd day, until a dose of 10 g/kg was attained on the 10th day and that dose was maintained by the 19th day) resulted in a reduction in the POMC mRNA level (about 20%) in the intermediate lobe of the pituitary (3 h after the last dose), whereas the level of beta-endorphin in the neurointermediate lobe was attenuated (by about 32%) only during the withdrawal (48 h after the last dose). Additionally, the plasma level of beta-endorphin after repeated ethanol and during withdrawal was significantly reduced (by about 44 and 66%, respectively). No changes in the POMC mRNA or the beta-endorphin levels were detected in the anterior lobe. In contrast, the PDYN mRNA level was found to be decreased in the anterior lobe during the withdrawal (by about 43%). This decrease was in conjunction with an increase in the alpha-neoendorphin level (by about 57%) in that lobe. The PDYN mRNA level in the intermediate lobe and the alpha-neoendorphin level in the neurointermediate lobe were unchanged after ethanol, as well as during the withdrawal period. Acute ethanol (5 g/kg) decreased the level of beta-endorphin in the anterior lobe; this effect being associated with an elevation in the peptide level in plasma. On the other hand, acute ethanol had no effect on the POMC and PDYN mRNA levels, nor did it affect the alpha-neoendorphin concentration in the pituitary. The results of our study indicate that acute and repeated ethanol differentially affects the biosynthesis of opioid peptides in the specific lobes of the pituitary. In the light of an opioidergic local regulation of endocrine secretion, these effects may participate in hormonal disturbances which are common in chronic alcoholics.

Cocaine addiction is a chronic relapsing disease with periods of chronic escalating self-exposure, separated by periods of abstinence/withdrawal of varying duration. Few studies compare such cycles in preclinical models. This study models an "addiction-like cycle" in mice to determine neurochemical/molecular alterations that underlie the chronic, relapsing nature of this disease. Groups of male C57BL/6J mice received acute cocaine exposure (14-day saline/14-day withdrawal/13-day saline + 1-day cocaine), chronic cocaine exposure (14 day cocaine) or chronic re-exposure (14-day cocaine/14-day withdrawal/14-day cocaine). Escalating-dose binge cocaine (15-30 mg/kg/injection x 3/day, i.p. at hourly intervals) or saline (14-day saline) was administered, modeling initial exposure. In "re-exposure" groups, after a 14-day injection-free period (modeling abstinence/withdrawal), mice that had received cocaine were re-injected with 14-day escalating-dose binge cocaine, whereas controls received saline. Microdialysis was conducted on the 14th day of exposure or re-exposure to determine striatal dopamine content. Messenger RNA levels of preprodynorphin (Pdyn), dopamine D1 (Drd1) and D2 (Drd2) in the caudate putamen were determined by real-time PCR. Basal striatal dopamine levels were lower in mice after 14-day escalating exposure or re-exposure than in those in the acute cocaine group and controls. Pdyn mRNA levels were higher in the cocaine groups than in controls. Long-term adaptation was observed across the stages of this addiction-like cycle, in that the effects of cocaine on dopamine levels were increased after re-exposure compared to exposure. Changes in striatal dopaminergic responses across chronic escalating cocaine exposure and re-exposure are a central feature of the neurobiology of relapsing addictive states. (C) 2012 Elsevier Ltd. All rights reserved.