Further definition of the effect of corticosterone on the sleep-wake pattern in the male rat.
It is well known that the activation of the hypothalamic-pituitary-adrenal (HPA) axis can induce alterations in the sleep-wake pattern. Corticotropin-releasing factor (CRF), adrenocorticotropin, and corticosterone are involved in the activation of the axis and each one of them has shown an effect on wakefulness and sleep. Nevertheless, concerning corticosterone, the picture is still controversial. In the present study, we analyzed the effects of a low (LC, 0.2 mg), medium (MC, 2 mg), and high (HC, 4 mg) dose of corticosterone on the 24-h sleep cycle in rats. Results indicate that all doses produce an initial enhancement of wakefulness with a concomitant decrease of slow-wave sleep II (SWS II). This effect was observed within the first hour in all the doses but lasted until the third hour only after the higher doses. When plasma levels of corticosterone were analyzed by high-performance liquid chromatography (HPLC), the highest levels were observed during the first 3 h, which is coincident with an increase in the percentage of wakefulness. Nevertheless, when the overall percentage of the stages was analyzed, LC seemed to induce the opposite effect (decrease of wakefulness and increase of SWS II) than that induced by the two higher doses (increased wake time, decreased SWS II). Rapid eye movement (REM) sleep was not modified at any dose. These data indicate that corticosterone exerts an alerting effect that could be important in the initial stage of the stress response.
Vázquez-Palacios
G
G
Department of Reproductive Biology, Universidad Autonoma Metropolitana-Iztapalapa, CP 09340, Iztapalapa, Mexico City, DF, Mexico.
Retana-Márquez
S
S
Bonilla-Jaime
H
H
Velázquez-Moctezuma
J
J
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000097:blood / Q000494:pharmacology*; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012894:Sleep Stages / Q000187:drug effects* / Q000502:physiology; D014851:Wakefulness / Q000187:drug effects* / Q000502:physiology
D000893:Anti-Inflammatory Agents; D003345:Corticosterone