Inhibition of gap junction intercellular communications of cultured rat hepatocytes by ethanol: role of ethanol metabolism.
OBJECTIVE
In a previous study, we reported that in cultured rat hepatocytes, ethanol inhibits intercellular communication which is known to play a central role in the regulation of cell growth and differentiation. This work was designed to find out if ethanol exerts a direct action on cell membranes, comparable to other long-chain (C6-C9) alcohols, or an indirect action.


METHODS
Intercellular communication was measured on short-term cultured rat hepatocytes by the fluorescent Lucifer-Yellow CH transfer method. Intracellular pH was measured by spectrofluorimetry and membrane expression of connexin 32 by indirect immunofluorescence.


RESULTS
Under our conditions, ethanol (20 mM) inhibited intercellular communication of hepatocytes to the same extent as did octanol and 1 mM. Immunofluorescence semi-quantitative studies of connexin 32 suggested that the observed inhibition was not related to a decrease in the number of gap junction plaques. In contrast with those of octanol, the inhibitory effects of ethanol appeared to be indirect because the inhibition of ethanol metabolism by 4-methyl pyrazole abolished its effects on intercellular communication, while 4-methyl pyrazole did not influence the effects of octanol. Acetaldehyde, the main metabolite of ethanol was without effect on gap junctions.


CONCLUSIONS
This suggests that the inhibition of intercellular communication induced by ethanol may be included among the consequences of intermediary cell metabolism disturbances indirectly due to ethanol oxidation. This may be one of the mechanisms by which ethanol metabolism exerts a hepatotoxic possibly carcinogenic action.
Abou Hashieh
I
I
Inserm U260, Faculté de Médecine, Marseille, France.
Mathieu
S
S
Besson
F
F
Gerolami
A
A
D020003:1-Octanol; D000079:Acetaldehyde / Q000494:pharmacology; D000818:Animals; D002450:Cell Communication / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D017630:Connexins / Q000187:drug effects / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D000077604:Fomepizole; D017629:Gap Junctions / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D007546:Isoquinolines; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D000442:Octanols / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013050:Spectrometry, Fluorescence; D000097002:Gap Junction beta-1 Protein
D020003:1-Octanol; D000079:Acetaldehyde; D002492:Central Nervous System Depressants; D017630:Connexins; D000431:Ethanol; D005456:Fluorescent Dyes; D000077604:Fomepizole; D007546:Isoquinolines; D000442:Octanols; D011720:Pyrazoles; D000097002:Gap Junction beta-1 Protein; C017475:lucifer yellow