Ethanol effects on total sialic acid of various brain regions and visceral organs

These experiments were designed to extend our earlier observations on acute ethanol effects on brain sialic acid (SA), an acidic sugar component of membrane gangliosides and many glycoproteins. Here, we tested for differential effects of ethanol on total sialic acid in various brain regions and for effects on other organs, such as liver, kidney, heart, and skeletal muscle. Subjects were young adult, male rats. The first experiment compared two commonly accepted analytical methods for brain SA on peripheral tissues. Consistently higher levels were evident with the resorcinol method in all tissues, especially in liver, compared with the thiobarbiturate method. Resorcinol-measured levels in the liver and kidney were on the order of 350 micrograms/g, wet weight. In the brain of controls, the resorcinol method revealed total SA levels to be on the order of 550-650 micrograms/g in the basal ganglia, cerebral cortex, cerebellum, and hippocampus. Brainstem levels were significantly lower. Ethanol, given IP at 2 g/kg, seemed to decrease total SA in all brain regions at four hours after injection, with statistically significant decreases in the hippocampus and brainstem. With 3 g/kg, only the cerebellum showed a significant decrease at four hours, compared to saline-injected controls, but the decrease was large (25%). Analysis of the other organs showed that, compared to saline-injected controls, ethanol decreased SA in the liver. There was a small, but significant, decrease in heart SA at four hours after 3 g/kg. In skeletal muscle, ethanol significantly increased total SA at 2 g/kg, but not at 3 g/kg.(ABSTRACT TRUNCATED AT 250 WORDS)