Anaesthetic and forebrain modulation of raphe-coerulean interactions.

Variations in tyrosine hydroxylase (TH) activity and serotonin (5-HT) content in the rat locus coeruleus were measured four days after lesion of the nucleus raphe centralis superior. Lesions were made under either ether or pentobarbital anaesthesia and, in addition, (under ether) in rats pretreated with atropine or with lesions of the medial septum. Results showed a dissociation between 5-HT reduction and TH induction, differences due to the anaesthetic used, and a possible influence from limbic centres on 5-HT in the LC. These findings are discussed in terms of the apparent complexity of raphe-coerulean interactions.