ABSTRACT
The origin of the serotoninergic innervation of the rat subcommissural organ was studied using radioautography of tritiated serotonin and biochemical determination of endogenous serotonin content after electrolytic lesions of raphe nuclei. The results suggest that this innervation is mainly derived from nuclei raphe centralis superior and raphe dorsalis, each nucleus contributing about one-third of the input. A possible contribution from nucleus raphe pontis is also suggested. Given the different patterns of innervation revealed by silver staining of nerve fibers and the different patterns of secretory activity observed with histochemical methods after the electrolytic lesions, the following working hypothesis is formulated. Nucleus raphe dorsalis would inhibit the synthesis of secretory material in the rat subcommissural organ via medium-sized serotoninergic fibers restricted to the hypendymal region, whereas nucleus raphe centralis superior might inhibit the release of secretory material via rather thin serotoninergic fibers reaching the nuclear level of the ependyma. This hypothesis is in line with the inhibitory effect postulated for the serotoninergic innervation in the rat subcommissural organ in early investigations using serotonin neurotoxins.
Subject(s)
Cerebral Aqueduct/physiology , Serotonin/physiology , Animals , Autoradiography , Cerebral Aqueduct/analysis , Histocytochemistry , Male , Raphe Nuclei/physiology , Rats , Rats, Inbred Strains , Serotonin/analysis , Staining and LabelingABSTRACT
A nonpeptide morphine-like compound (MLC) which cross reacts with morphine-specific antibodies has been localized with the use of immunocytochemistry. This morphine-like compound is found in neuronal perikarya or processes (or both) in nuclei related to vestibular, cerebellar, and raphe systems.
Subject(s)
Brain Chemistry , Morphine/immunology , Animals , Cerebellum/analysis , Cerebral Aqueduct/analysis , Cross Reactions , Immunoenzyme Techniques , Mice , Raphe Nuclei/analysis , Vestibular Nuclei/analysisABSTRACT
Silver-impregnated series of cat and monkey (Cercopithecus aethiops) brains were studied in an attempt to demonstrate the existence of nervous connections between the brain and the pineal gland via the pineal stalk (central pineal connections). The presence of such connections between both the pineal gland and the habenular area, and between the pineal gland and the posterior commissure was verified in this study. A well defined median nerve tract between the pineal gland and the posterior commissure is described.
