Modulation of desynchronized sleep through microinjection of α₁-adrenergic agonists and antagonists in the dorsal pontine tegmentum of the cat

Noradrenaline is involved in the regulation of the sleep/waking cycle by acting through various receptor types. In previous studies we investigated the role of β- and α₂-adrenergic receptors through local microinjections of various drugs into the dorsal pontine tegmentum (DPT) of the cat. This region is known to be crucially involved in desynchronized sleep execution. In this study we examined the role of α₁-adrenergic receptors. The α₁-agonist methoxamine and the α₁antagonist prazosin were injected into the DPT of freely moving, unaesthetized cats. We found that methoxamine notably reduced desynchronized sleep, and that this effect was both dose-dependent and site-specific. These effects were prevented by the subsequent injection of prazosin. On the other hand, the injection into the DPT of prazosin alone produced scarce or inconsistent effects on the sleep/waking cycle.