CHANGES IN THE ENTEROCYTE CYTOSKELETON IN NEWBORN RATS EXPOSED TO ETHANOL IN-UTERO

Background-Cytoskeletal changes after longterm exposure to ethanol hav e been described in a number of cell types in adult rat and humans. Th ese changes can play a key part in the impairment of nutrient assimila tion and postnatal growth retardation after prenatal damage of the int estinal epithelium produced by ethanol intake. Aims-To determine, in t he newborn rat, which cytoskeletal proteins are affected by longterm e thanol exposure in utero and to what extent. Animals-The offspring of two experimental groups of female Wistar rats: ethanol treated group r eceiving up to 25% (w/v) of ethanol in the drinking fluid and control group receiving water as drinking fluid. Methods-Single and double ele ctron microscopy immunolocalisation and label density estimation of cy toskeletal proteins on sections of proximal small intestine incubated with monoclonal against actin, alpha-tubulin, (polypeptides 1, 5, 6, 7 , 8, 10, 11, and 18), and with a polyclonal antibody anti-beta 1,4-gal actosyl transferase as trans golgi (TG) or trans golgi network (TGN) m arker, or both. SDS-PAGE technique was also performed on cytoskeletal enriched fractions from small intestine. Western blotting analysis was carried out by incubation with the same antibodies used for immunoloc alisation. Results-Intestinal epithelium of newborn rats from the etha nol treated group showed an overexpression of cytoskeletal polypeptide s ranging from 39 to 54 kDa, affecting actin and some cytokeratins, bu t not tubulin. Furthermore, a cytokeratin related polypeptide of 28-29 kDa was identified together with an increase in free ubiquitin in the same group. It was note-worthy that actin and cytokeratin were abnorm ally located in the TG or the TGN, or both. Conclusions-Longterm expos ure to ethanol in utero causes severe dysfunction in the cytoskeleton of the developing intestinal epithelium. Actin and cytokeratins, which are involved in cytoskeleton anchoring to plasma membrane and cell ad hesion, are particularly affected, showing overexpression, impaired pr oteolysis, and mislocalisation.