Fig. 3. Noninvasive in vivo measurements of extracellular enzymatic activity (DPP-4) in non-transgenic mice: direct comparison of stationary CCD camera (IVIS® Spectrum) and PBL readouts.
a Maximal photon flux obtained from four groups of nude mice (n = 5) resulting from administration of a DPP-4-specific caged luciferin probe12 and DPP-4 inhibitor sitagliptin (“SIT”). The “SIT” groups of mice received an oral gavage of different concentrations of SIT (5 and 10 mg/kg) 30 min prior to injection of the probe, while the control group received a gavage of vehicle only (PBS buffer). All the mice received s.c. injection of 100 µL of luciferase plug in the dorsal area followed by signal acquisition with the IVIS® Spectrum. The “blank” group of mice received injection of the plug without caged luciferin probe. b Maximum signal output from the experiment described in (a) except that the measurements were performed using the portable light detector. c–d Representative images of two mice from the control (c) and 10 mg/kg sitagliptin-treated (d) groups. Data are presented as the mean ± s. d. (n = 5). Each “n” represents a biologically independent sample. Statistical significance (****P < 0.0001) was calculated using a two-tailed unpaired t-test. Source data is available as a Source Data file for (a and b).