Ultrastructural and biochemical studies of the brain and other organs in rats after chronic ethanol administration

The aim of the present study was to follow the ultrastructural changes occurring in neuronal intracellular structures of the rat cerebral cortex after chronic administration of ethanol. The experiments were carried out with 15 Wistar rats. Nine of them received alcohol, while six served as control group. According to Ratcliffe's model, the animals received ethanol to drink in increasing concentrations so that they became adapted to it. Examinations were performed on 3 groups of animals: Group I receiving for 4 weeks ethanol in concentrations increasing from 2.5 to 10 per cent; Group II receiving for 8 weeks ethanol in concentrations increasing from 2.5 to 25 per cent; Group III receiving for 12 weeks ethanol in concentrations increasing from 2.5 to 25 per cent and given for the last 4 weeks simultaneously 42 per cent ethanol through a gastric tube every second day.

In the animals of group I, a marked decrease of the number of ribosomes and polysomes was observed in the neuronal cytoplasm and a slight reduction of the rough endoplasmic reticulum (RER). In the cells with a well-developed smooth endoplasmic reticulum (SER) mitochondria exhibited a number of abnormalities in the form of a reduced number of cristae, their aggregation in the central part of the matrix and the appearance of mitochondria markedly elongated in shape.

In experimental group II, the changes in the neuronal cytoplasm were more pronounced as compared with those in group I. In the peripheral part of the cytoplasm a wide extension of channels of the RER and proliferation of SER were observed. The above mentioned disturbances in the cytoplasm were usually accompanied by changes in the mitochondria consisting in their increased number and size, reduced electron density of the matrix, and greatly reduced number of cristae.

Most of the cortical neurones in group III exhibited abnormalities in the RER and SER similar to those described in animals of group II.

The most severe changes were observed in the mitochondria consisting in an increased size with deformation of monstrous shapes. Some mitochondria were greatly enlarged but of spherical shape with myelin-like structures inside.

The changes in the above mentioned structures suggest that ethanol easily penetrates through the blood-brain barrier and glial cells to the neurones. Although alcohol produces severe abnormalities in the mitochondria and enhances the spread of the SER, it does not lead to destruction of the neurones of the cerebral cortex.