Activity of the hypothalamic-pituitary-adrenocortical system and sleep-wake cycle in rats with acute systemic inflammation.

Activity of the hypothalamic-pituitary-adrenocortical system and EEG characteristics of the sleep-wake cycle were studied on adult male Wistar rats with acute inflammation produced by bacterial lipopolysaccharide in a dose of 250 microg/100 g body weight. Blood concentrations of adrenocorticotropic hormone and corticosterone increased by 6 and 10 times, respectively, 30 min after lipopolysaccharide administration and peaked 2 hours after challenge. In this period the sleep-wake cycle underwent the most pronounced changes that could be attributed to the stupor-like state observed in clinical practice. It was manifested in dissociation between locomotor activity of animals and EEG characteristics, suppression of EEG components in slow-wave sleep, increase in the number of beta-waves, and decrease in the number of delta-waves in EEG. In the present work we consider possible mechanisms of temporal relationships between activity of the hypothalamic-pituitary-adrenocortical system and disorganization of the sleep-wake cycle during acute systemic inflammation.