Histocytochemical Analysis for New Vasoactive Substances in CNS

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Recently, some humoral agents which play a role in water-balance, electrolyte metabolism and blood pressure control, i. e. ANP/BNP/CNP family (ANPs), endothelin (ET) and endogenous digitalis-like substance (EDLS) were identified and their chemical stucture determined. In this research, we analyzed these vasoactive substances with a histocytochemical technique using the central nervous system of rat, pig, dog and macaque.The nerve terminals of ANP- and BNP-neurons were observed in the posterior horn of the spinal cords of rats and pigs. The BNP-neurons were seen in the pig hypothalamus, but were not found in the rat brain except the spinal cord. These results were confirmed by biochemical and physiological reports, which proposed that BNP existed mainly in the mammalian heart but not in the brain ; and CNP, a new peptide of ANPs is found in mammalian brain.ET-immunoreactivities were not recognized in the mammalian central nervous system. The central nervous tissues have 10^2pg/g of ET, … More which level of bioactive substance cannot be detected with immunohistochemistry, though there were some immunohistochemical reports using the mammalian brain. In those reports, the researcher used the antibody, the epitope which had high homology in nelation to other bioactive substances. We made a ontogenetical study on this neuropeptide, i. e. ET in the rat with immunohistochemical and molecular biological technique. ET was first detected on day 19 of gestation in a salivary gland. Because ET is also considered to be a cell-proliferation factor, ET is possible to be the secondary discovered NGF (nerve growth factor).EDLS were histochemically studied using anti-digoxin and anti-ouabain antibodies which have highーaffinity to EDLS. EDLS-neurons were distributed in the magnocellular nuclei of mammalian hypothalamus. Recent biochemical study shows EDLS resembles to ouabain, cis-trans-cis type steroid of plant origin. It is thought that cis-trans-cis type steroid exists in the mammalian brain as a neurohormone. Less