Glycogen Synthesis and Immunocytochemical Study of Fructose-1,6-Biphosphatase in Methionine Sulfoximine Epileptogenic Rodent Brain

Abstract

The effects of the convulsant methionine sulfoximine (MSO) on the glucose pathway have been investigated in mouse and rat brain. The key gluconeogenic enzyme fructose-1,6-biphosphatase (FBPase) (EC 3.1.3.11) was immunostained by rat anti-FBPase antibody. The rat cortex slices were very lightly stained, almost unstained in controls. After MSO injection, there was a marked staining only in astrocytes (perikarya, processes, and end feet). The activity of this enzyme also increased. MSO induced an increase of 63% in the stability at heating (47°C) and of 36% in the stability at proteolysis (trypsin, 10 μg/ml) of FBPase. The convulsant had no effect on the concentrations of the metabolites related to the FBPase–phosphofructokinase step, i.e., fructose-1,6-biphosphate, glyceraldehyde-3-phosphate, and dihydroxyacetone phosphate, before, during, or after the convulsions. These results show that the cellular site of glucose pathway impairment induced by MSO in rodent brain is presumably the astroglial cells and that one mechanism of glycogenesis could be the reinforcement of the molecules of FBPase, which enhances gluconeogenesis. A hypothetical diagram of glucose metabolism under the effect of MSO has been proposed.