The possible role of c-fos protein in hypothalamus in sleep disturbance inchronic uremic rats

Sleep disturbance is very common in patients with chronic renal failure, bu t its mechanism is not clear. The activity of c-fos protein (FOS) in ventro lateral preoptic neurons (VLPO) is associated with the sleep pattern. The p urpose of this study was to evaluate the relationship between sleep disturb ance and the expression of FOS in VLPO of chronic uremic rats. Chronic urem ia was induced by the 5/6 nephrectomized model. The movements of the rats w ere measured with infrared monitoring during the daytime (8.00-20.00) and n ighttime (20.00-8.00). Rats were killed at 10.00 or 16.00 h for the daytime (uremic rats 7, control 8) and at 22.00 h for the nighttime (uremic rats 7 , control 9). The expression of FOS in VLPO was examined with the immunohis tochemical method. The number of recorded daytime movements in uremic rats was significantly higher than in control rats (458 +/- 185 vs. 222 +/- 41, p < 0.001), but the number of recorded nighttime movements in uremic rats w as lower than in control rats (949 +/- 430 vs. 1,618 +/- 261, p< 0.001). in the daytime, the number of FOS immunoreactive cells in uremic rats was low er than in control rats (18.4 +/- 5.3 vs. 42.8 +/- 6.3, p < 0.001), but the re was no difference between two groups in the nighttime (10.8 +/- 8.4 vs. 12.5 +/- 5.1, p = 0.62). There was a strong negative correlation between th e number of recorded movements and the number of FOS immunoreactive cells i n VLPO (r = -0.700, p < 0.001). This finding suggests that sleep disturbanc es in chronic uremic rats might be related to the decreased expression of F OS in VLPO.