The effect of triiodothyronine on the hippocampal long-term potentiation in an animal model of the Alzheimer's disease: The role of BDNF and reelin

•Administration of T3 improved long-term potentiation (amplitude and slope) in AD rats.•Administration of T3 increased the expression of reelin and BDNF expression in the hippocampus of AD rats.•Administration of T3 regulated the hippocampal levels of THs and TSH.•Administration of T3 was reduced the Aβ plaques in the periventricular region of the brain.•I.H. microinjection of T3 was more effective than S.C.