Phytohormone abscisic acid ameliorates cognitive impairments in streptozotocin-induced rat model of Alzheimer's disease through PPARβ/δ and PKA signaling.

Aim: Alzheimer's disease (AD) is characterized by oxidative stress, neuroinflammation and progressive cognitive decline. Abscisic acid (ABA) is produced in a variety of mammalian tissues, including brain. It has anti-inflammatory and antioxidant effects and elicits a positive effect on spatial learning and memory performance. Here, the possible protective effect of ABA was evaluated in streptozotocin (STZ)-induced AD rat model which were injected intracerebroventriculary (i.c.v.) with STZ (3 mg/kg). Material and Methods: The STZ-treated animals received ABA (10 μg/rat, i.c.v.), ABA plus PPARβ/δ receptor antagonist (GSK0660, 80 nM/rat) or ABA plus selective inhibitor of PKA (KT5720, 0.5 μg/rat) for 14 d. Learning and memory were determined using Morris water maze (MWM) and passive avoidance (PA) tests. Results: The data showed that STZ produced a significant learning and memory deficit in both MWM and PA tests. ABA significantly prevented the learning and memory impairment in STZ-treated rats. However, ABA effects were blocked by GSK0660 and KT5720. Conclusion: The data indicated that ABA attenuates STZ-induced learning and memory impairment and PPAR-β/δ receptors and PKA signaling are involved, at least in part, in the ABA mechanism.