BACKGROUNDThe relationship between melanosis coli (MC) and aquaporin 8 (AQP8) has not yet been elucidated. The aim of this research was to investigate the relationship between the expression of AQP8 and the pathological mechanism of MC.

METHODSExpression of AQP8 was detected by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) in 37 MC colon tissues and 13 control colon tissues. Global gene expression analysis was also used to identify differently expressed genes. Its relationship with MC was analyzed by SPSS 11.5 statistical software.

RESULTSThe positive rate of AQP8 expression detected by immunohistochemistry in the MC group was 24.3% (9/37), significantly lower than the 69.2% (9/13) in the control group (P < 0.05). The relative expression level of AQP8 in MC group was 0.639 ± 0.160, lower than 0.921 ± 0.148 of controls (P < 0.05). Global gene expression analysis showed that AQP8 mRNA expression was downregulated in MC patients.

CONCLUSIONSThe decreased AQP8 expression in MC patients indicates that chronic use of laxatives containing anthraquinone may cause reduced water absorption. The expression of AQP8 may be related to MC.