HTR6 and Cognitive impairment: Blocking the 5-HT6R has been shown to enhance acetylcholine levels.347, 348, 349 In line with this, cognitive impairment in rats caused by scopolamine-induced cholinergic deficits was restored by numerous 5-HT6R antagonists, including SB-271046, SB-399885, SB-742457, Ro-04-6790, Ro-4368554, CMP X, and CMP Y.348,355,391,393,396,398, 399, 400 In contrast, another study reported that the 5-HT6R antagonist SB-271046 reversed scopolamine-induced learning deficits in rats only when applied in combination with the AChEI galanthamine.392