The multiple forms of brain acetylcholinesterase. I. Micro-electrophoresis and topochemical analysis of the pattern

Differences in response of acetylcholinesterase to diisopropylfluorophosphate in the mesencephalic raphe region. A microelectrophoretic, histochemical, and biochemical study in albino rats

To demonstrate the DFP-effects on the AChE of the mesencephalic raphe region albino rats were investigated using the pharmaco-histochemical method of Butcher et al. (1975). At several times after 1 mg DFP/kg body weight, the histochemical reactions in certain AChE-containing neurons were measured semiquantitatively and compared with biochemical data. Additionally, the multiple forms of water-soluble AChE were separated by microelectrophoresis. Only the electrophoretical results indicate changes of the structural AChE composition 5 d after DFP administration.

The heterogeneity of the nucleus raphes dorsalis in albino rats. A fluorescence histochemical and microelectrophoretic study

In albino rats, the nucleus raphes dorsalis (NRD) of the midbrain was investigated using a sensitive fluorochroming procedure to detect indolamines in combination with a microelectrophoretic method to demonstrate the isoenzyme pattern of acetylcholinesterase (AChE). Based on the fluorescence histochemical appearance, 3 types of indolaminergic cells were identified in the various areas of the NRD. According to data of the literature and in agreement with our own results, the morphological heterogeneity of the NRD was shown. Significant differences of AChE specific zymograms of NRD regions (subgroups) demonstrate that organization of NRD is heterogeneously proved not only by morphological results but also in respect of enzyme constitution.

The multiple forms of brain acetycholinesterase. III. Implications for the histochemical demonstration of acetylcholinesterase

The multiple forms of acetylcholinesterase (AChE, E.C. 3.1.1.7) have been investigated with regard to their histochemical demonstrability. Their pattern is influenced by buffer treatment, fixation, and by incubation conditions causing aggregation and disaggregation as well as loss or inactivation of individual forms. The standard histochemical method for AChE preferentially demonstrates the high molecular forms. Most of the oligomer forms are washed out or inactivated. A selective demonstration of the highly aggregated forms is possible either by inhibition of the oligomers with diisopropylfluoridate (DFP) or by specifically dissolving them out. No reason could be found for the selective demonstration of the low molecular weight forms.

The multiple forms of brain acetylcholinesterase. II. A suggestion of their functional importance

The pattern of the multiple forms of the acetylocholinesterase (AChE, E.C. 3.1.1.7) of the rat brain is investigated using polyacrylamide gradient micro-gel electrophoresis with regard to a possible functional importance of this individual forms. The patterns of the AChE-forms of selected regions of the CNS are compared and certain differences could be shown. After increased cholinergic input (into the hippocampus by electrical stimulation of the nc. septi medialis) an aggregation of AChE subunits is detectable. Subletal intoxication with an irreversible inhibitor of AChE is followed by a faster recovery of the smaller forms. A suggestion of a possible functional role of the multiple forms of AChE is discussed.