To monitor the constitutive and induced PPAR activity, transgenic mice were treated without or with rosiglitazone and imaged 6 hours later. As shown in Figure 2(A), the diffuse luminescence was detected throughout the body and the intense signals were emitted in the head and abdominal region. Administration of rosiglitazone significantly induced the PPAR-dependent luminescent signals in mice. Ex vivo imaging showed that the maximal intensity was observed in the brain, moderate luminescent signals were observed in liver and stomach, and slight intensity was observed in heart, lung, spleen, kidney, and intestine (Figure 2(B)). Administration of rosiglitazone increased the PPAR-dependent luminescent intensity in brain and stomach. These data indicated that endogenous PPAR activities were widely present in most organs and the greater endogenous PPAR activities were observed in brain, liver, and stomach. Moreover, rosiglitazone activated the PPAR activities in the brain and stomach, which was consistent with previous studies [28], suggesting that PPRE transgenic mice could be applied to report the PPAR activity in vivo.
