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It has long been thought that the treatment of core anxiety symptoms will produce a satisfactory resolution of insomnia. Genistein, the principal isoflavone constituent of soybean, has been reported to exert anxiolytic-like effects in rats. Whether genistein modulates sleep behavior, however, remains to be elucidated. In the present study, we examined the effect of genistein on sleep-wake profiles in freely moving mice by EEG and EMG recording as well as immunohistochemical staining for c-Fos. Our results showed that genistein administered i.p. at doses of 80 and 160 mg/kg significantly increased the amount of non-rapid eye movement (non-REM, NREM) sleep and as well as the number of NREM sleep episodes, with a concomitant reduction of wakefulness. It increased the state transitions from wakefulness to NREM sleep and subsequently from NREM to wakefulness. However, genistein neither had an effect on the amount of REM sleep nor on EEG power density of NREM or REM sleep. Immunostaining revealed a reduction of c-Fos expression in neurons of the locus coeruleus and the tuberomammillary nucleus after administration of genistein, as compared with the vehicle control. These results indicate that treatment with genistein leads to an inhibition of arousal-promoting neurons and thus promotes NREM sleep, suggesting its potential application for the treatment of insomnia. [ABSTRACT FROM AUTHOR]

The suprachiasmatic nucleus (SCN) is a master circadian pacemaker. It regulates the 24 h timing of many physiological processes, including sleeping and waking. After bilateral SCN lesions, the circadian rhythm of the sleep-wake cycle was completely eliminated, but the characteristics of the sleep-wake profile were not well clarified. In the present study, bilateral suprachiasmatic nucleus lesions (SCNX) were created in rats to determine the effects of SCNX on the sleep-wake profile in terms of number of episodes, mean duration of each stage and number of transitions between stages. Although bilateral SCN lesions completely eliminated the circadian rhythm in the sleep-wake cycle, there was no significant change in the total amount of daily sleep or wakefulness before and after lesions. However, the SCN-lesioned rats exhibited an increased episode number of wake and non-rapid eye movement (NREM) sleep during dark period and a decreased one during light period. The mean duration of wakefulness decreased significantly during the dark period and increased during the light period. The number of transitions between NREM sleep and wakefulness increased during the dark period and decreased during the light period. The NREM sleep power density and total number of episodes, number of transitions, and mean duration were not significantly different from those of sham controls when viewed over 24 h. These results indicate that lesions of suprachiasmatic nucleus did not alter the total amount of daily sleep but did modify the structure of sleep-wake profiles in rats. [ABSTRACT FROM AUTHOR]