introduction: retinoid signaling has been argued to have favorable effects on alzheimer's disease (ad). we studied the role of chronic intracerebroventricular (icv) injection of all-trans retinoic acid (atra) on the amyloid-beta (aβ) model of ad. methods: adult male rats weighing 260-330 g were divided into 12 groups of 8 each. six groups of rats received atra (3nm, 30nm, 3μm, 0.3mm, 30mm/...