1986 Volume 49 Issue 4 Pages 181-186
The effect of serial bathing in city water or Misasa hot spring on the circadian variation of plasma corticosteroid (11-OHCS) was studied in both young normal and old hypercholesteremic rats. Both groups of rats were divided into three subgroups: rats bathed in hot spring, 40°C, once daily for one and four weeks; rats bathed in city water, 40°C, once daily for one and four weeks; rats non-treated for one and four weeks. Plasma obtained by decapitation at 8:00, 12:00, 16:00, (18:00), 20:00 and 24:00 hours was analyzed for 11-OHCS. Following results were obtained.
1) In young normal rats, the range of the circadian variation tended to decrease after 1-week serial bathing, particularly after the serial hot spring bathing. However, it remained almost unaltered after 4-week serial bathing. The results suggest adaptation of the rats to the serial bathing. Average concentration of plasma 11-OHCS tended to increase after 1-week and 4-week serial bathing.
2) Old hypercholesteremic rats showed less circadian variation as compared with young normal rats and old normal rats.
The circadian variation in the old hypercholesteremic rats was almost unaffected after 1-week serial bathing, although the average concentration of plasma 11-OHCS was increased, particularly after the 1-week city water bathing.
After the 4-week serial bathing, on the other hand, the range of the circadian variation tended to be augmented, particularly in the 4-week hot spring bathing rats: the nadir value was decreased by about 30 percent and the peak value was increased by about 30 percent as compared with each value in non-treated rats.
The results suggest the normalizing effect of the 4-week serial hot spring bathing on the circadian rhythm. Average concentration of plasma 11-OHCS was scarcely affected after the 4-week serial bathing.