Andrzej Z. Pietrzykowski, Gilles E. Martin, Sylvie I. Puig, Thomas K. Knott, Jose R. Lemos, and Steven N. Treistman
Often the best drug can be "dirty" in that it has multiple mechanisms of action. That certainly seems to be true of ethanol, which can act on a number of receptor systems in the brain. This week, two reports zero in on the actions of ethanol on ligand- and voltage-gated ion channels.
2. Opiate-Induced Sensitization of the Locus Ceruleus
Guang-Ping Xu, Elisabeth Van Bockstaele, Beverly Reyes, Thelma Bethea, and Rita J. Valentino
Chronic opiate use results in an array of neurological changes, many of which fuel drug-seeking behaviors. Noradrenergic neurons in the locus ceruleus (LC) contribute to the stress response, an activity that is enhanced by corticotropin-releasing factor (CRF) and reduced by endogenous µ-opioids. This balance, Xu et al. postulate this week, can be upset by chronic opiate use. CRF receptor expression did not increase with chronic morphine, but the authors propose that sensitization relies on changes upstream of the formation of cAMP. This action of chronic opiates can enhance responsiveness to stressful stimuli and may thus contribute to continued drug-seeking behaviors.