Presentations

N-butyrate, produced in gastrointestinal microbial fermentation or added as a feed supplement in some species, has several biological effects. It is one of the most important energy supplier substrates of the gastrointestinal cells, while it is also absorbed and transported with the portal and systemic circulation to different organs, where modifies gene expression, has an influence on the synthesis of certain enzymes and hormons, and can cause important morphological changes. Butyrate can also modify division, differentiation and apoptosis of certain cells.

These effects are mainly determined by the uptake and metabolism of butyrate by the cell, because these influence the intracellular concentration of butyrate and the intracellular pH. The aim of our study was to examine, how much butyrate can be taken up and metabolised by cultured rat hepatocytes of the liver, which organ plays a central role in the intermediary metabolism. Our research group has already carried out such examinations on cultured chicken hepatocytes in the Department of Pharmacology and Toxicology, so we also wanted to compare the results of these two species.

Hepatocytes were isolated from the experimental animals with a three-step perfusion and digestion by collagenase enzyme, then primary cell cultures were developed. Cultures were characterized by immunhistochemical detection of specific marker proteins, such as glutaminase, IGFBP-1 and α-smooth muscle-actin. After 24 hour cultivation cell culture medium was supplemented with different concentrations of Na-n-butyrate (0, 1, 5 és 10 mmol/l). After additional 24 hour incubation, from the supernatant of the cultures butyrate and acetate concentration was determined by gas chromatography.

At 1 mmol/l butyrate supplement hepatocytes took up the whole amount of butyrate in both species. Significant difference could be found at higher concentrations: after treatment with 5 mmol/l butyrate, it was fully taken up by rat hepatocytes, while only 19,67 ± 3,86 % relative uptake was measured at chicken hepatocytes. At 10 mmol/l supplement 75,71 ± 6,26 % uptake proportion was found in rat, while only 15,12 ± 1,31 % in chicken. In addition, huge amount of acetate was produced and given down by the rat hepatocytes, while there was no acetate production in chicken cell cultures.

It can be concluded from our results, that the transport mechanisms of butyrate uptake may differ in the hepatocytes of these two examined species. In the chicken hepatocytes it could be mainly passive transport, which is primarily affected by the dissociation of the molecule. Presumably, a monocarboxylate transporter could play the main role in rat hepatocytes. Butyrate taken up by the cells, is metabolized intensively. Cytoplasmic acetyl-CoA-hydrolase, which transforms acetyl-CoA to acetate, is missing in chicken hepatocytes, so these cells cannot produce and give down any acetate.