The transporters analyzed in this study are known to be regulated by different mechanisms, involving various transcription factors such as Ppar-α, Pxr, constitutive androstane receptor (Car), nuclear factor E2-related factor 2 (Nrf2), Fxr, and Hepatocyte nuclear factor 1-alpha (Hnf-1α). Li and Klaassen (2004) showed that HNF1α levels are critical for constitutive expression of Slco1b2 in mouse liver [54]. Also Slc22a6 and Slc22a7 expression in mouse kidneys is downregulated by targeted disruption HNF1α [55]. Significantly reduced expression of Slco1a1

in liver, along with Slc22a7 in kidney in db/db mice suggests that HNF1α levels or binding is decreased in these mice. Similarly, Abcc3 and Abcc4 efflux transporter expression is regulated in part by Nrf2-keap1 pathway in liver [24]. The present study clearly demonstrates that Abcc2-4 were upregulated in livers of db/db mice, which suggests activation of the Nrf2 and/or find more constitutive androstane Selleckchem MK2206 pathways in these mice. Increased mRNA expression of Nrf2 and its target gene Gclc indicate that Nrf2-keap1 pathway is likely activated in db/db mice. The Nrf2-keap1 pathway is activated during periods of oxidative stress [56]. Also as reviewed by Rolo and Palmeira, diabetes is typically accompanied by increased production of free radicals, present findings suggests that oxidative stress may be present in diabetic liver

[57]. Together, the data presented argue for additional future studies to better define nuclear receptor pathways that are upregulated in leptin/leptin receptor deficient models, which will aid in better

understanding receptor-mediated mechanisms, which could regulate transporter expression in steatosis and T2DM. As reviewed by Klaassen and Slitt [38], Car and Pxr are also known for regulating CYTH4 Abcc2, 3, 5, 6 and Abcc2, 3 respectively. The observed increase in Abcc2, 3, 5, and 6 expression could be attributed to the observed increased in Car expression and activity, as shown in Figure 7. Similar to the liver, transporter expression is markedly altered in kidneys of db/db mice. Maher and colleagues showed that targeted disruption in Hnf1α significantly downregulated Slc22a6, 7 and 8 and Slco1a1 mRNA in mice kidneys [55]. This indicates that db/db mice might have differential expression or binding of Hnf1α. Also, these mice have severe hyperglycemia. During normal course, almost all of the glucose is absorbed from the nephrons during urine formation. But due to overwhelming amounts of glucose in glomerular filtrate, kidneys are unable to absorb it and thus excrete glucose in urine. This hyperglycemic urine may cause some alterations in transporter expression in kidneys. Conclusions Data illustrated in the present study illustrate a comprehensive, panoramic view of how a severe diabetes phenotype affects liver and kidney transporter expression in mice.