Circadian disturbance of clock gene expression is a risk factor of diseases like obesity, cancer and sleep disorder. For the study of these diseases, it is necessary to monitor and analyze the expression rhythm of clock genes in the whole body for a long duration. In previous studies, we showed a tissue contact optical sensor system to detect the Per1 expression rhythm in freely moving mouse. In the present study, we developed micro PMT system which directly attached target tissue in freely moving mouse. Using this technique, we were able to analyze circadian rhythms of clock gene expression over a prolonged period with very high sensitivity.
In present studies, we show micro PMT system detect Per1 gene expression rhythm over 10000 times comparing with the tissue contact optical sensor system. Per1 expression rhythm in the back skin of freely moving mouse had a peak at CT12. At this time point, we found high Per1 expression in whole hair root tissue using micro PMT system in STZ diabetes mouse. These results show that micro PMT system will be widely applied to many areas of biomedical research, as well as finding applications beyond medicine.