Journal of Neuroscience, Vol 2, 829-842, Copyright © 1982 by Society for Neuroscience
The sites of origin brain stem neurotensin and serotonin projections to the rodent nucleus raphe magnus
AJ Beitz
The combined horseradish peroxidase retrograde transport-peroxidase-
antiperoxidase immunohistochemical procedure was utilized in the present
study to ascertain the sites of origin of serotonin and neurotensin
projections to the rodent nucleus raphe magnus. The major serotonin inputs
to the raphe magnus arise from the B-8 and B-9 groups of Dahlstrom and Fuxe
(Dahlstrom, A., and K. Fuxe (1964) Acta Physiol. Scand. Suppl. 232 62:
1-55), the nucleus reticularis paragigantocellularis, and the nucleus
reticularis gigantocellularis pars alpha. Neurotensinergic projections to
the raphe magnus originate predominantly from the periaqueductal gray, the
nucleus solitarius, the dorsal and ventral parabrachial nuclei, and the
nucleus cuneiformis. The periaqueductal gray and the nucleus
paragigantocellularis were found to provide both a neurotensin and a
serotonin projection to this raphe nucleus. The present results indicate
that several brain stem nuclei, which have been implicated previously in
endogenous analgesia mechanisms, provide serotonergic and neurotensinergic
input to the nucleus raphe magnus.
