Changes in Body Temperature and Sleep-Wakefulness AfterIntrapreoptic Injection of Methoxamine in Rats

[摘要] Several pieces of evidence suggest that thenoradrenergic afferents in the medial preopticarea produce sleep and hypothermia by actingonα1adrenergic receptors. On the other hand,in a few studies monitoring body temperaturewith a rectal probe, preoptic injection of theα1adrenergic agonist methoxamine producedcontradictory changes in body temperature andsleep-wakefulness. Such contradictions call forthe re-examination of methoxamine inducedbody temperature changes using a bettertechnique like telemetric recording. In thepresent study, we monitored body temperatureand sleep-wakefulness simultaneously after themicro-injection of 0.5, 1, and 2μmolmethoxamine, into the medial preoptic area ofadult male Wistar rats. Methoxamine injectionproduced hypothermia but no major change insleep-wakefulness during the 3 hours after druginjection, except for a short period (15 min) ofsleep after 120 min of injection. A short periodof wakefulness, coinciding with the maximumfall in body temperature (30 min after injection)occurred when methoxamine was administeredat higher doses. The results of this study indicatethat 1 adrenergic receptors participate in preopticallymediated thermoregulatory measuresthat reduce body temperature. Hypothermiainduced by methoxamine might have maskedthe hypnogenic action of this drug.

[学科分类] 精神健康和精神病学