Regulation of nociceptin mRNA expression in the septum by dopamine and adenosine systems

Most effects of nociceptin are related to blockade of stress and anxiolytic -like effects. This neuropeptide is highly expressed in septal nuclei, whic h are involved in response to stressful situations. Dopamine and adenosine may have modulatory effects on stress behaviour by acting on septal neurons . We therefore analysed the regulation of septal nociceptin expression usin g quantitative in situ hybridization following manipulations of adenosine a nd dopamine neurotransmission. No difference was observed between wild-type and A(2A) receptor-deficient mice. In both genotypes, chronic treatments w ith caffeine, an equipotent A(1) and A(2A) adenosine receptor antagonist, d id not significantly modify nociceptin expression. 6-Hydroxydopamine-induce d dopamine depletion was also without effect. These results demonstrate tha t dopamine and adenosine are not involved in the regulation of septal nocic eptin expression in spite of the involvement of these three neurotransmitte rs in stress and anxiety behaviours. NeuroReport 11:3243-3246 (C) 2000 Lipp incott Williams & Wilkins.