Serum hormone levels during sleep and wakefulness in the immature female rat

Variations in serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), prolactin (PRL), growth hormone (GH), and corticosterone in the states of arousal, slow wave sleep and paradoxical sleep were studied as a function of time from the onset of arousal and sleep which were determined polygraphically in 27- to 30-day-old female rats. Markedly high LH values occurred more frequently during slow wave sleep than during other stages, resulting in a tendency to greater mean LH levels in the state of slow wave sleep. Variations in PRL values at various states of the sleep-waking cycle were not very large, but a statistically significant peak occurred shortly after the sleep onset. The mean PRL values obtained after 5 min of paradoxical sleep were lower than those obtained during slow wave sleep. Mean GH values were higher during sleep than arousal state, and the mean during paradoxical sleep was highest. GH levels peaked at 30 min after sleep onset. Corticosterone values were highest in the arousal state, and decreased abruptly after 20 min of sleep. There were no significant variations in FSH and TSH levels in serum during various sleep-waking states. These secretory patterns of anterior pituitary hormones during a sleep-waking cycle are quite similar to those in man.