title: Morphine tolerance and dependence in the locus coeruleus: single cell studies in brain slices.
abstract: Extracellular single unit recordings in vitro from the locus coeruleus in rat brainstem slices revealed the presence of spontaneously active neurons. These cells fired between 0.1 and 3.0 spikes/s and were inhibited by nM concentrations of morphine and clonidine. Locus coeruleus neurons in slices from animals treated chronically, but not subacutely, with morphine exhibited a significant decrease in sensitivity to morphine. This tolerance appeared to be specific for opiates since no decrease in sensitivity was seen for the alpha 2-adrenoceptor agonist clonidine. However, in contrast to what has been reported in vivo, no signs of dependence (withdrawal activation) were evident in slices from morphine tolerant animals.
mesh_terms: D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004361:Drug Tolerance; D006801:Humans; D066298:In Vitro Techniques; D008125:Locus Coeruleus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009021:Morphine Dependence; D009474:Neurons / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009020:Morphine; D003000:Clonidine