Local infusion of an α-1 adrenergic agonist into the prefrontal cortex impairs spatial working memory performance in monkeys

Background: Stimulation of α-2 adrenoceptors in the monkey or rat prefrontal cortex (PFC) has been known to improve spatial working memory (SWM) and stimulation of α-1 adrenoceptors in the rat PFC has been reported to impair SWM. The present study attempted to replicate in monkey the rat experiments on α-1 adrenoceptor stimulation. Methods: The α-1 adrenergic agonist phenylephrine or the α-2 adrenergic agonist guanfacine was infused into the dorsolateral prefrontal cortex (dlPFC) of monkeys performing the delayed-response (DR) task, a task of SWM, to see how the drugs affect SWM performance. Results: Phenylephrine infusion in dlPFC significantly impaired DR performance, whereas guanfacine improved performance. The effects of both drugs were delay-dependent. Infusions outside dlPFC were ineffective. Conclusions: Stimulation of prefrontal cortical α-1 adrenoceptors impairs SWM function in monkeys, consistent with the parallel study in rats, whereas stimulation of α-2 adrenoceptors improves SWM, indicating that α-1 and α-2 adrenoceptors may have opposing roles in the PFC.