MODULATION OF AMPA RECEPTOR SUBUNITS GLUR1 AND GLUR2 3 IN THE RAT CEREBELLUM IN AN EXPERIMENTAL HEPATIC-ENCEPHALOPATHY MODEL/

The immunohistochemical expression and distribution of the AMPA-select ive receptor subunits GluR1 and GluR2/3 were investigated in the rat c erebellum following portocaval anastomosis (PC,A) at 1 and 6 months, W ith respect to controls, GluR1 and GluR2/3 immunoreactivities increase d over 1 to 6 months following PCA, although immunolabelling patterns for both antibodies were different at the two analysed times. GluR1 im munoreactivity was expressed by Bergmann glial cells, which showed imm unoreactive glial processes crossing the molecular layer at 6 months f ollowing PCA. The GluR2/3 subunit was expressed by Purkinje neurons an d moderately expressed by neurons of the granule cell layer. Immunorea ctivity for GluR2/3 was detectable in cell bodies and dendrites of Pur kinje cells in young control cerebella, whereas GluR2/3 immunoreactivi ty was scarce 1 month post PCA. However, despite a lack of immunoreact ivity in the Purkinje somata and main processes of adult control rats, GluR2/3 immunoreactivity was strongly enhanced in Purkinje neurons fo llowing long-term PCA. These findings suggest that the localization of the GluR2/3 subunit in Purkinje cells undergoes an alteration and/or reorganization as a consequence of long-term PCA. The combination of e nhanced GluR immunoreactivity in long-term PCA, both in Bergmann glial cells and in Purkinje neurons, suggests some degree of neuro-glial in teraction, possibly through glutamate receptors, in this type of encep halopathy. (C) 1997 Elsevier Science B.V.