AR-R17779, an α7 nicotinic agonist, improves learning and memory in rats

Nicotinic acetylcholine systems have been found to be important for learning and memory function. The prototypic nicotinic agonist nicotine has been shown in a variety of studies to improve aspects of cognitive function. The specific involvement of nicotinic receptor subtypes is now being investigated.. The involvement of alpha 7 nicotinic receptors was assessed in this project using a novel alpha 7 nicotinic agonist, AR-R 17779. Repeated doses (subcutaneous injection 20 min before testing) of the racemic mixture AR-R 13489 and its active isomer AR-R 17779 were assessed in adult female Sprague-Dawley rats using the eight-arm radial maze. AR-R 13489 (2 mg/kg) caused a significant improvement of longterm win-shift acquisition after 3 weeks of training (n = 10 per group). The same dose of AR-R 17779 also caused a significant improvement in repeated acquisition within each daily session in the radial-arm maze. In another study, the active isomer AR-R 17779 significantly improved radial-arm maze working memory function in rats with lesions to the septohippocampal projection. Fimbria-fornix lesions significantly impaired working memory performance and AR-R 17779 significantly reversed that impairment. These studies showed that alpha 7 nicotinic agonist treatment improved learning in two radial-arm maze tasks and reversed working memory impairment caused by fimbria-fornix sections, providing evidence for alpha 7 involvement in learning and memory, and the potential therapeutic use of AR-R 17779. (C) 1999 Lippincott Williams & Wilkins.