Metabolism of glycoconjugates in hypothalamic neurons and glial cells: Comparison of incorporation of [3H]fucose and [3H]N-acetylmannosamine by electron microscopic autoradiography
Incorporation of 3H-fucose into hypothalamic tissue of rats was studied between ten minutes and seven days after intraventricular injection. In EM autoradiographs grain densities over perikarya of neurons, astro-, and oligodendroglia, and neuropil were evaluated. Grain densities were consistently higher over both types of glial cells as compared to neurons. The glia/neuron ratio was especially high after short experimental intervals and declined with increasing time intervals. Concomitantly there was an increase of grain density over the neuropil. The discussion concentrates on the methodical aspects which have to be considered in interpreting the autoradiographic data. It is concluded that both astroglia and oligodendroglia exhibit a considerably higher synthesis rate of glycoproteins per unit volume than nerve cells. The implications of the results for the interpretation of biochemical data on glycoprotein metabolism of brain tissue are discussed.