Incorporation of N‐Acetylmannosamine into Rat Brain Subcellular Gangliosides: Effect of Pentylenetetrazol‐Induced Convulsions on Brain Gangliosides¹

Abstract

The labeling pattern of the major individual gangliosides from the microsomal and synaptosomal fractions of rat brain was determined following intracerebral injection of the radioactive sialic acid precursor, N‐acetylmannosamine. Microsomal gangliosides initially had a higher specific radioactivity than synaptosomal gangliosides, with both fractions reaching similar specific radioactivities 18 h after precursor injection. In both subcellular fractions, the polysialogangliosides GT1b and GQ1b were initially more highly labeled than all other gangliosides. With the establishment of the labeling pattern, the effect of the convulsant pentylenetetrazol on brain gangliosides was examined in detail. Significant decreases in radioactive label were noted in the polysialogangliosides, GT1b and GQ1b, from the synaptosomal and microsomal fractions of the convulsed animals. The decreases may be due to activation of the membrane‐bound neuraminidase present with the gangliosides in neuronal tissue. Prior to experimentation, a methodology was developed to insure quantitative isolation of small amounts of ganglioside free of other lipids and water‐soluble contaminants. Combination of this isolation procedure with quantitative densitometry of thin‐layer chromatograms permits accurate distributional analyses for individual gangliosides. In applications involving radioactive gangliosides, the method allows the determination of both radioactivity and sialic acid distributions from the same thin‐layer chromatogram.

Gangliosides associated with microsomal subfractions of brain: Comparison with synaptic plasma membranes

“…Since analytical methodologies are subject to variation in different laboratories, comparisons carried out in the same laboratory are perhaps more instructive than comparisons between laboratories. Analogous to this study, Avrova et al (1973) also found similarities in ganglioside patterns of unfractionated SPM and MIC and more recently Yohe et al (1980) observed closely similar patterns between microsomes and whole synaptosomes of rat brain.…”

“…Generally similar patterns were previously reported for microsomal gangliosides of rat brain (Avrova et al, 1973;Yohe et al, 1980) and rabbit brain (Tettamanti et al, 1973), although those studies reported somewhat lower values for G M~ and higher values for GD~,. The SPM ganglioside pattern obtained in this study showed lower proportions of GD2/GTla, and GDlb and more G M~ than that reported previously for unfractionated SPM (Avrova et al, 1973).…”

Cellular Distribution of Gangliosides in the Developing Mouse Cerebellum: Analysis Using the Staggerer Mutant

“…the plasma membrane. Support for this assumption comes from studies of ganglioside biosynthesis, where no precursor-product relationship is found between the simple and complex gangliosides (Caputto et al, 1974; Maccioni et al, 1977;Yohe et al, 1980;Miller-Podraza and Fishman, 1983). In other words, most gangliosides exist in the plasma membrane as end-products, rather than intracellularly as precursors.…”

Region‐specific and epileptogenic‐dependent expression of six subtypes of α2,3‐sialyltransferase in the adult mouse brain

“…1999). In addition, pentylenetetrazol‐induced seizures affect the contents of the subcellular gangliosides (Yohe et al . 1980).…”

“…Alternatively, it was proposed that gangliosides containing sialic acid, in which the contents in the brain were fivefold greater than that in other tissues (Iwamori and Nagai 1981), have a supporting effect on the regulation of calcium and nitric oxide in signaling in the plasma membrane (Rahmann 1995;Pyo et al 1999). In addition, pentylenetetrazol-induced seizures affect the contents of the subcellular gangliosides (Yohe et al 1980). However, how these molecules contribute to neural plasticity remains essentially unknown.…”