Distribution and quantification of 5-HT nerve cell bodies in the nucleus raphe dorsalis area of C57BL and BALBc mice. Relationship between anatomy and biochemistry.

BALBc and C57BL mice have been shown to have a different 5-HT metabolism. The present study compares the number and the distribution of 5-HT cell bodies in the nucleus raphe dorsalis area (B7 + B6) of these strains. By using 5-HT immunohistochemistry, we found a higher number of 5-HT neurons in the most caudal part of NRD (B6) of BALBc mice compared to C57BL. This difference may be correlated with a higher level of endogenous 5-HT, a higher uptake capacity toward exogenous [3H]5-HT, and a lower release of the amine in this same area of BALBc mice compared to C57BL. It could also imply a significant participation of the nerve cell bodies in the regulation of 5-HT transmission inside 5-HT nuclei.