Localization of Hexokinase in Neural Tissue: Immunofluorescence Studies on the Developing Cerebellum and Retina of the Rat

Abstract: Antiserum against purified rat brain hexokinase (ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1) has been used in a study of the distribution of hexokinase during the postnatal development of rat cerebellum and retina. The cells of the external germinal layer of the cerebellum exhibit little or no fluorescence. The Purkinje cells exhibit a transient increase in hexokinase levels between 2 and 8 days postnatally, followed by a precipitous decrease (8–12 days) to the relatively low levels found in the mature Purkinje cell. Development of the intensely fluorescent cerebellar glomeruli in the granule cell layer is readily followed during the 3rd and 4th weeks postnatally. With respect to postnatal changes in hexokinase distribution of the retina, perhaps most notable is the observation that even the cytoplasmic protrusions which represent the precursors of the photoreceptor segments are richly endowed with hexokinase. Biochemical differentiation of the photoreceptor segments into hexokinase-rich inner segments and hexokinase-poor outer segments is readily observed long before the growth of the photoreceptor segments has been completed.