Effects of the adenosine A^sub 2A^ antagonist istradefylline on cognitive performance in rats with a 6-OHDA lesion in prefrontal cortex

• Published in: Psychopharmacology Vol. 230; no. 3; p. 345
• Main Authors: Kadowaki Horita, Takako, Kobayashi, Minoru, Mori, Akihisa, Jenner, Peter, Kanda, Tomoyuki
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.12.2013
• Subjects: Animal cognition; Animal memory; Dopamine; Parkinson's disease; Psychopharmacology; Rodents
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s00213-013-3158-x

Altered cognitive function is a common feature of both the early and later stages of Parkinson's disease (PD) that involves alterations in cortical dopamine content. Adenosine A^sub 2A^ antagonists, such as istradefylline, improve motor function in PD, but their effect on cognitive impairment has not been determined. The present study investigated whether impairment of working memory due to the loss of dopaminergic input into the prefrontal cortex (PFC) is reversed by administration of istradefylline. We also evaluated whether A^sub 2A^ antagonist administration modulates dopamine levels in the PFC. Bilateral lesions of the dopaminergic input to the PFC were produced in rats using 6-hydroxydopamine (6-OHDA). Cognitive performance was evaluated using an object recognition task and delayed alternation task. The effects of istradefylline, donepezil and methamphetamine on cognitive performance were examined. In addition, the effect of istradefylline on extracellular dopamine levels in the PFC was studied. PFC dopamine levels and cognitive performance were significantly reduced by 6-OHDA lesioning. Istradefylline, donepezil and methamphetamine improved cognitive performance of PFC-lesioned rats. Istradefylline increased dopamine levels in the PFC in both normal and PFC-lesioned rats. PFC dopaminergic input plays an important role in working memory performance. Blockade of A^sub 2A^ receptors using istradefylline reverses the changes in cognitive function, and this may be due to an increase in PFC dopamine content. Adenosine A^sub 2A^ receptor antagonists not only improve motor performance in PD but may also lead to improved cognition.[PUBLICATION ABSTRACT]