Nano tag viewer program

Sleep fragmentation associated with OSA may cause daytime sleepiness [36 (link)]. Sleepiness can be indirectly observed to record locomotor activity [37 (link)]. Nano-Tags (18.8 × 14.2 × 7.1 mm³, 2.7 g; Kissei Comtec Co. Ltd., Nagano, Japan) were implanted under the skin of the back under 3% isoflurane anesthesia more than 10 days before recording. Nano-Tag methodology identifies sleep–wake states in animals [38 (link)]. The locomotor activity was recorded every 30 seconds and stored in Nano-Tag, and the data were transferred to the Nano-Tag Viewer program (Kissei Comtec Co. Ltd.) percutaneously at 11:00 under light isoflurane anesthesia. Two hours of data obtained from 11:00 to 13:00 were excluded from the analysis. The data were collected as the average of each hour. In the Nano-Tag device measurements, activity was defined as cross-count data, providing a count of the number of times the XYZ acceleration vector synthesized waveform crossed the threshold levels from the bottom (170/min) to the top (170/min) per recording interval. Locomotor activity was measured in group-housed rats (2–3 rats/cage) in each experimental group to prevent social separation stress.

The 24-h spontaneous activity of each rat was recorded with Nano tag® (Kissei Comtec Co, Nagano, Japan) for evaluation of fatigue state. The Nano tag® was implanted subcutaneously between the scapulae of each rat according to the manufacture's instruction. Briefly, the implanting operation was performed 10 days before fatigue-loading procedure under anesthesia induced by 2% pentobarbital sodium. After the operation, 100 mg/kg ampicillin sodium was injected subcutaneously for each rat to prevent infection. The rats were allowed to recover for 10 days before the fatigue loading procedure. All the rats were individually housed in their home cages. After 10 days of recovery from the operations, these rats were as active as the normal rats. The level of spontaneous activity was recorded from 3 days before fatigue loading to 4 days after the end of the fatigue-loading procedure. The spontaneous activity level was normalized to the mean value of the 3 days before fatigue loading. Spontaneous activity was analyzed using the Nano-tag viewer program (Kissei Comtec Co., Nagano, Japan).

Locomotor activity was measured as cross-count data using the Nano-Tag system. First, a 3-axis composite wave was generated from the X, Y, and Z values measured by a Nano-Tag 3-axis accelerometer. For each recording interval, the number of moments crossing the 3-axis composite wave threshold was recorded as locomotor activity [21 (link)]. The threshold was set to 100. Subsequently, we obtained a measure of locomotor activity using the Nano-Tag/Viewer program (Kissei Comtec Co., Ltd.). The activity counts were separated into 1-h increments.