Nerve-ending gangliosides

Gangliosides and Associated Enzymes at the Nerve-Ending Membranes... 

Gangliosides. sialidase and sialvltransferase in the membranes surrounding nerve endings ( synaptosomal membranes )... 

The neuraminidases together with gangliosides have been localized in the nerve ending structures (6, 7 ). Theoretically the sialylation and desialylation cycle may mediate a cyclic reaction at a very important locale in a nerve synaptic structure. This hypothetical involvement of sialic acid metabolism in synaptic transmission has gained support from several studies which have suggested a synaptic localization of the glycosyltransferases (8, 9,10,11) and from proposed theoretical models in which the sialo-glycolipids are considered an important constituent in the functional units of neuronal membranes (12,13,14). 

Ganglioside Complex carbohydrate-rich glycosphingolipids containing three or more monosaccharides esterified to ceramide with at least one of the sugars being A-acetylneuraminic acid (sialic acid). Gangliosides are membrane components found on nerve endings. 

Information on the intracellular distribution of gangliosides is somewhat controversial. On the basis of the reports available, it seems difficult to decide whether gangliosides are located in the microsomal, the lysosomal, or the nerve ending vesicles. 

Tissue fractionation studies of guinea pig brain by differential centrifugation followed by gradient density separation have led to the claim that gangliosides are present in the nerve ending vesicles with acetylcholine. It is claimed that gangliosides form 10-12% of the dry weight of the synaptic vesicles [112]. 

The data of Lapetina et aL (1967) on rat brain cortex seen in Table I are rather similar to those of others listed above. In general, the microsomal and especially the mitochondrial fractions can be further fractionated to yield pinched off nerve endings or synaptosomes. These are essentially of plasma membrane origin and are especially rich in gangliosides and bound acetylcholine. Synaptosomes can be ruptured by osmotic shock to release synaptic vesicles that are virtually free of gangliosides. 

The left sciatic nerve branch to EDL muscle was transected in adult female rats and the ends of the two stumps of the transected nerve were tied together. Some of the operated animals were treated daily, during the entire post-operative period, with 50mg/kg i.p. of a mixture of brain cortex gangliosides (Fidia S.p.A., Abano Terme,... 

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