[The role of norepinephrine in down-regulation of visceral sensitivity in rats deprived of rapid eye movement sleep].

OBJECTIVE

To investigate the role of norepinephrine in the down-regulated visceral sensitivity of rats deprived of rapid eye movement (REM) sleep.

METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into 3 groups: cage-yoked rats as control (YC), rats with REM sleep deprivation (SD) and rats with yohimbine administered intraperitoneally after REM sleep deprivation (YSD). Flower pot technique was employed to make sleep deprivation model. YSD group was given yohimbine intraperitoneally at the 48th hour after REM sleep deprivation. After both SD and YSD groups had completed these processes, rats of all the three groups were given colorectal distension (CRD) and electromyogram (EMG) was recorded at the same time. The number of discharges of EMG and the threshold of pain perception of the rats were observed to evaluate the visceral sensitivity. The thalamus, rectum and distal colon were taken after CRD; MAO-mRNA and TH-mRNA in three tissues were detected with RT-PCR.

RESULTS

On 48th hour, the number of discharges of EMG in 10 seconds responding to CRD in group SD was significantly less than that in group YC and the threshold of pain perception in group SD was higher than that in group YC (P < 0.05). The number of discharge of EMG in group YSD was significantly more than that in group SD (P < 0.05). The expression of MAO-mRNA in group SD was lower than that in group YC (P < 0.05) and the expression of TH-mRNA in group SD was higher than that in group YC (P < 0.05).

CONCLUSIONS

The visceral sensitivity in rats is down-regulated by REM sleep deprivation, which can increase synthesis of norepinephrine. Norepinephrine can modulate visceral sensitivity.