Non-invasive oxidative stress measurement in the craniofacial region using ESR

Objectives:

Oxidative stress induced by reactive oxygen species (ROS) generated by the irradiation of ultraviolet ray (UV) related to various disease such as carcinogenesis and nephropathy. ROS may be involved in craniofacial disease, including skin aging (photoaging), while only a few in vivo studies have been reported the inference of oxidative stress induced to UV irradiation, directly. In this study, we investigated the direct influence of oxidative stress exposed by UV in the craniofacial region using in vivo L-band electron spin resonance (ESR) technique.

Methods:

Female hairless mice (Hos:HR-1) were divided into 3 groups; control (non irradiation), UV-A, and UV-B. After anesthetized by pentobarbital (50 mg/kg), mice were injected with 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidin-1-yloxy (C-PROXYL, 140 mM) via tail vein. The decay rate constant of C-PROXYL in the craniofacial region of the mice were measured by in vivo L-band ESR imaging system. While the measurement, UV irradiation (50 mW/cm²) was exposed at a distance of 5 cm from the eyes. In addition, the decay of C-PROXYL in the craniofacial region was reconstructed by ESRCT.

Results:

Both UV-A and UV-B irradiation increased the decay rate constant of C-PROXYL in the craniofacial region compared to control (Student's t test, p<0.05). No significant differences of the decay rate constant of C-PROXYL in the craniofacial region between UV-A and UV-B. We also obtained the 2D ESR images of C-PROXYL in the craniofacial region of the mice after exposure by UV-A or UV-B.

Conclusions:

In this study, we could measure the oxidative stress in the craniofacial region of the mice induced by the irradiation of UV-A and UV-B using L-band ESR and ESR imaging system. These results suggested that in vivo L-band ESR could be powerful technique for non-invasive evaluation of the ROS-induced oxidative stress in craniofacial disease of small animal models.