Effect of Intra-CA1 injection of estrogen on spatial memory and learning in rats

Introduction: Sexhormones are one of most important factors in difference of learning and memory between tow sexes (male & female). High concentration of estrogen and androgen receptors and mechanism of testosterone and estrogen production in learning and memory center, especially in hippocampus show the role of this receptors, sexhormons and P450 enzymes in spatial memory. Consequently, in this study we evaluate effect of estradiol valerat and aromatase inhibitor (Anasterazole) on spatial learning and memory in Morris Water Maze. Materials and methods: Adult male rats were bilaterally connulated into CA1 region. After recovery period, control groups received DMSO 0/5µl and DMSO 0/5µl + DMSO 0/5µl. Different doses of estradiol valerat (EV) (1, 2.5, 5, 10 and 15µg / 0.5µl), anastrozole (An) (0.25, 0.5, 1µg / 0.5µl) and EV 15µg / 0.5µl +An 0.5µg / 0.5µl were microinjected all days before training. EV was injected 30-35 min before training and anastrozol was injected 25-30min before training. Result: Our results have showen EV 0.15µl / 0.5µl group increase escape latency and traveled distance. Also we have showen that anastrosole dose dependently decrease escape latency and traveled distance. Conclusion: We resulted that EV impaired acquisition of spatial learning and memory but anastrozole improved it. Anastrozole also couldn't be buffered EV – induced impairment.