MOSAIC DISTRIBUTION OF CHONDROITIN AND KERATAN SULFATE IN THE DEVELOPING RAT STRIATUM - POSSIBLE INVOLVEMENT OF PROTEOGLYCANS IN THE ORGANIZATION OF THE NIGROSTRIATAL SYSTEM

The striatum of the mammalian basal ganglia is composed of two neuroch emically distinct compartments termed patches and matrix that contribu te overall to a mosaic organization. Glycosaminoglycans (GAGs), the su gar moieties of proteoglycans, provide specific spatio-temporal guidan ce cues during the development of several functional neural systems. H owever, their distribution within the nigrostriatal system has not bee n investigated yet. Here, the immunohistochemical distributions of uns ulphated (COS), 4-sulphated (C4S) and 6-sulphated chondroitin (C6S) an d keratan sulphate (KS) were examined in the developing neostriatum of rat and compared with the distribution of dopaminergic terminals. All the chondroitin sulphate (CS) isomers are homogeneously expressed in the embryonic striatum. After birth, COS and C6S reveal the striatal m osaic in being preferentially expressed within the matrix compartment and in boundaries around patches whereas the C4S epitope is present in both compartments, with a slight patchy distribution. KS expression i s detected first in the patches during the early postnatal period and subsequently only in the matrix compartment. All these GAG expressions disappear as the brain matures except for C4S which remains high thro ughout adult life. Furthermore, studies within the developing medial f orebrain bundle reveal that CS isomers, but not KS, are expressed in a nd around the dopamine axonal tract but show similar developmental pat terns of distribution which do not appear to be specifically associate d with the nigrostriatal pathway. These results suggest a possible imp lication of proteoglycans during the development of the striatum and m ay be useful for understanding the complex cellular and molecular inte ractions in degeneration and plasticity of the nigrostriatal circuit i n Parkinson's disease. (C) 1998 Elsevier Science B.V. All rights reser ved.