Modulation of CYP3a expression and activity in mice models of type 1 and type 2 diabetes

Abstract

CYP3A4, the most abundant cytochrome P450 enzyme in the human liver and small intestine, is responsible for the metabolism of about 50% of all marketed drugs. Numerous pathophysiological factors, such as diabetes and obesity, were shown to affect CYP3A activity. Evidences suggest that drug disposition is altered in type 1 (T1D) and type 2 diabetes (T2D). The objective was to evaluate the effect of T1D and T2D on hepatic and intestinal CYP3a drug-metabolizing activity/expression in mice. Hepatic and intestinal microsomes were prepared from streptozotocin-induced T1D, db/db T2D and control mice. Domperidone was selected as a probe substrate for CYP3a and formation of five of its metabolites was evaluated using high performance liquid chromatography. Hepatic CYP3a protein and mRNA expression were assessed by Western blot and reverse-transcription quantitative polymerase chain reaction respectively. Hepatic microsomal CYP3a activity was significantly increased in both T1D and T2D groups versus control group. Intestinal CYP3a activity was also significantly increased in both T1D and T2D groups. Moreover, significant increases of both hepatic CYP3a mRNAs and protein expression were observed in both T1D and T2D groups versus control group. Additional experiments with testosterone further validated the increased activity of CYP3a under the effect of both T1D and T2D. Although differences exist in the pathophysiological insults associated with T1D and T2D, our results suggest that these two distinct diseases may have the same modulating effect on the regulation of CYP3a, ultimately leading to variability in drug response, ranging from lack of effect to life-threatening toxicity.

Cyp3a11‐mediated testosterone‐6β‐hydroxylation decreased, while UGT1a9‐mediated propofol O‐glucuronidation increased, in mice with diabetes mellitus

“…Though midazolam and testosterone are both substrates of human CYP3A4 (mouse CYP3a11), CYP3A4 is characterized by a large substrate‐binding pocket containing six substrate recognition sites . Previous studies showed that the change of activities of midazolam‐1‐hydroxylation and testosterone‐6β‐hydroxylation mediated by CYP3A4 or CYP3a11 were different and diabetes had different effects on these substrate recognition sites . Similar results were observed in the present study, indicating that the effect of diabetes mellitus on Cyp3a11 activity might vary with the substrate.…”

“…Although it is known that Cyp2b10 and Cyp4a mRNA and protein levels increase, Cyp1a2 protein levels decrease, and the activities of Cpy3a11 , Cyp2b10 and Cyp2c29 increase in db/db mice, to date, changes in other CYP enzymes activities and UGT enzyme activities have not been reported in db/db mice. In this study, the activities of the main drug‐metabolizing enzymes, including eight CYP‐mediated, nine phase I metabolic reactions and three UGT‐mediated glucuronidation reactions were fully studied in db/db mice.…”

“…Third, in the present study, diabetes mellitus caused a decrease in the formation of testosterone‐6β‐hydroxylation in 20‐week‐old db/db mice. However, Dany et al demonstrated that hepatic microsomal testosterone‐6β‐hydroxylation activity increased in 7‐week‐old db/db mice . This difference may indicate that the changes in the activity of CYP3a11, catalysing testosterone‐6β‐hydroxylation, might vary according to the course of diabetes mellitus.…”

“…A number of drug‐metabolizing enzymes are regulated by nuclear receptors. In addition, CYP3A‐related metabolism was proved to be constitutive androstane receptor (CAR)‐mediated . It has been reported that mRNA transcription of CAR increased in 7‐ and 10‐week‐old db / db mice , however, no significant change was observed in 25‐week‐old db / db mice .…”

“…Yoshinari et al demonstrated changes in the expression of four P450s in db/db mice after detecting the mRNA and protein levels of six P450s, but P450s activities were not assessed , which are most important in reflecting the metabolic ability of drug‐metabolizing enzymes. Other studies reported modifications of metabolic enzymes in db / db mice and only one or several CYP activities were clarified (Table ). Therefore, changes in the activities of important P450s and UGTs in db / db mice still need to be investigated.…”