Cytochemical and immunocytochemical comparative localization and characterization of acid sulfated glycolaminoglycans (sGAG) in several areas of the rat cerebral cortex during postnatal development

Abstract

There are some evidences demonstrating that Acid Sulfated Proteoglycans take part in several Central Nervous System (CNS) functions (Brittis et al., 1992; Carbonetto, 1989; Carey et al., 1990, 1992; Fichard et al., 1991; Kalb and Hockfield, 1990; Lafont et al., 1992; Schubert and Lacorbiere, 1985; Schubert et al., 1988, 1989; Snow et al., 1990, 1991, 1992). To date, the immunocytochemical methods have been developed to detect different proteglycans using specific monoclonal antibodies (Bertolotto et al., 1991; Watanabe et al., 1989; Zaremba et al., 1989). The aim of the present paper is to compare the localization of chondroitin-0-sulfate, -4-sulfate, -6-sulfate and keratan sulfate proteglycans in the rat cerebral cortex during the postnatal development, using both colloidal iron and immunocytochemical methods. Our observations, with the light microscope, revealed an intense immunocytochemical reaction closely associated to the neuronal membranes that, in most cases, were located in the III, IV, V and VI cortical layers of the 20 and 30 postnatal day rats, but not in the 7 and 15 postnatal ones. The colloidal iron reaction revealed similar distribution as that one observed with the immunocytochemical method for chondroitin-0-sulfate, -4-sulfate, -6-sulfate proteoglycans. At electron microscopic level it has been observed positive immunostaining for these sulfated proteoglycans on the plasma membrane of these scattered neurons. Positive immunoreaction for Keratan sulfate proteoglycan was demonstrated inside several astrocytes of 7, 15, 20 and 30 postnatal day rat cerebral cortexes, but it has not been observed in neurons. Taking into account the previous biochemical studies, our observation have led us to suggest that a unique membranous protein could be binded to several acid sulfated glycosaminoglycans (sGAG) types in a particular neuronal subset.Peer Reviewe