Evidence for an interaction of opioid and noradrenergic locus coeruleus systems in the regulation of environmental stimulus-directed behavior.
The roles of opioid and noradrenergic (NE) dorsal bundle systems in an animal's response to particular environmental stimuli were examined in a multicompartment exploration chamber. The opiate antagonist naloxone (NAL) produced a stereo-specific increase in environmental stimulus interaction, while the opiate agonist morphine induced a NAL-reversible reduction in stimulus contact. Thus, a specific opioid role in environmental stimulus-directed behavior is indicated. Several reports suggest inhibitory actions of opioids on NE locus coeruleus (LC) activity. Consistent with these reports, we observed that 6-hydroxydopamine (6-OHDA) lesions of the NE dorsal bundles of the LC produced a morphine-like reduction in stimulus contact. Naloxone, which increased stimulus interaction in sham-lesioned rats, had no effect in dorsal bundle lesioned animals. These findings indicate an interaction between opioid and LC systems in the regulation of environmental stimulus-directed behavior.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism; D004723:Endorphins / Q000502:physiology*; D004777:Environment; D004837:Epinephrine / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D008125:Locus Coeruleus / Q000502:physiology*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D004723:Endorphins; D009270:Naloxone; D009020:Morphine; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine