ABSTRACT
BACKGROUND: Sex differences in drug pharmacokinetics have been well recognized and gender has been considered a risk factor for adverse events to medications. The aim of this study was to investigate the effect of gender on the expression of hepatocellular transport proteins involved in uptake and secretion of organic anions in rat. MATERIALS AND METHODS: Expression of the rat liver organic anion transporting polypeptides (Oatps) and multidrug resistance proteins (Mrps) was analysed by reverse transcription polymerase chain reaction (RT-PCR), immunoblot analysis and immunofluorescence microscopy in male and female rats. Regulation of these transport proteins in response to the steroid dehydroepiandrosterone (DHEA) was investigated. RESULTS: In untreated rats, protein expression significantly differed between genders being higher (Mrp2, Mrp3), comparable [Oatp1a1 (Oatp1); Oatp1b2 (Oatp4)] or lower [Oatp1a4 (Oatp2)] in female than in male rat. DHEA treatment over 3 days (100 mg d(-1)) led to a further increase in Mrp3 expression only in female rats. Mrp2 expression was not influenced by DHEA treatment. Oatp1a1 and Oatp1b2 were significantly down-regulated after DHEA treatment in both male and female rats. In contrast, Oatp1a4 was down-regulated in male rats only. CONCLUSIONS: In rat, liver transport proteins of the Oatp and Mrp family are expressed and regulated in a gender-specific manner according to sexual differences in the hepatic metabolism of steroids and drugs. These findings may partly explain the well-known sex differences in hepatic handling of organic anions.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B/metabolism , Liver/metabolism , Organic Anion Transporters/metabolism , Sex Characteristics , Animals , Dehydroepiandrosterone/pharmacology , Female , Fluorescent Antibody Technique , Immunoblotting/methods , Male , Mitochondrial Proteins/metabolism , Multidrug Resistance-Associated Proteins/metabolism , Organic Anion Transporters/genetics , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Reverse Transcriptase Polymerase Chain Reaction/methods , Ribosomal Proteins/metabolism , Saccharomyces cerevisiae Proteins/metabolismABSTRACT
In-situ immunoassays do not allow the detection of the minute numbers of target molecules accessible with in-situ PCR. We developed a highly sensitive method, termed in-situ immuno-PCR, in which the DNA marker was linked to target molecules through an antibody-biotin-avidin bridge and amplified by in-situ PCR. Amplified DNA sequences were detected in situ by hybridisation. This technique may be the only one available to detect minute quantities of biological macromolecules such as proteins, carbohydrates, and lipids in intact cells or tissue sections.
