[Effect of cholerogen and protamine on tight junctions of rat enterocytes and colonocytes]

Study of tight junction state and ultrastructure changes of rat jejunum enterocytes and colon colonocytes under the effect of cholerogen and protamine.

Cholerogen (cholera toxin, Sigma-Aldrich, Germany) and protamine sulfate (Russia) were used in the study. The study was carried out in Wistar line rats. Effect of cholera toxin and protamine on rat intestine epitheliocytes was carried out by incubating intestine segments in the respective solutions. Ultrastructure changes caused by cholerogen and protamine in rat enterocytes and colonocytes were assessed based on ultrathin section analysis by transmission electron microscopy of the cells themselves and tight junctions between them compared with control.

Effect of cholerogen on intestine mucous membrane epitheliocytes manifested in changes of cell ultrastructure, the form of which transformed as a result of increase of intercellular space without the destruction of tight junctions. Disappearance of cell plasma membrane lateral area folding and decrease of number of microvilli was noted. Enlargement of nuclei was noted only in individual cells. Effect of protamine on epithelial cell layer ultrastructure differed significantly from the effect of cholerogen. Increase of cell plasma membrane lateral area folding and significant enlargement of nuclei that moved to the central part of cells reaching its apical end were characteristic effects for protamine. Surface of a part of epitheliocytes lost microvilli with simultaneous destruction of tight junction structure. Protamine induced increase of folding only in colon without affecting jejunum. At the same time both of these substances caused increase of intercellular space in jejenum and colon epithelium.

Differences in ultrathin structure of rat small intestine and colon epitheliocyte tight junctions under the effect of cholerogen and protamine were revealed.