Monocarboxylate transporter 1 (MCT1) in the liver of pre-ruminant and adult bovines

This study investigated the distribution and expression of monocarboxylate transporter 1 (MCT1) in the livers of pre-ruminant calves and adult bovines (bulls and cows), using different molecular biological techniques. Reverse transcription-polymerase chain reaction (RT-PCR) verified the presence of mRNA encoding for MCT 1 in both pre-ruminant and adult bovine livers. Immunohistochemically, MCT1 was clearly demonstrated on the sinusoidal surfaces of bovine hepatocytes but its expression varied widely between pre-ruminants and adult bovines. In pre-ruminants, a faint hepatocellular expression of MCTI was observed in a few hepatocytes, whereas an intense immunoreactive staining for MCT1 was shown in the majority of adult bovine hepatocytes. Western blot analysis also confirmed the results of the immunohistochemistry. Quantitative immunoblotting, as estimated by densitometric analysis, showed that the level of MCT1 in the liver of adult bovines was 8-9-fold greater (P < 0.01) than that in pre-ruminant calf livers although no significant differences were detected between bulls and cows. The results demonstrated that NICTI may play a crucial role in the transport of propionate in bovine liver, suggesting that MCT1 expression may be influenced by developmental and metabolic regulations. (c) 2005 Elsevier Ltd. All rights reserved.