ABSTRACT
Introduction: The role of ovarian hormones and nitric oxide [NO] in learning and memory and their interaction has been widely investigated. The present study carried out to evaluate different effect of L-NAME on spatial learning and memory of ovariectomized [OVX] and sham operated rats. Methods: 32 rats were divided into 4 groups: 1] Sham; 2] OVX; 3] Sham-LN; and 4] OVX-LN. The animals of groups 3 and 4 were treated by L-NAME [10 mg/kg/ day] for 8 weeks while the animals of groups 1 and 2 received saline [1ml/kg/day] instead of L-NAME. The animals of all groups were then tested in Morris water maze during five days. The escape latency and traveled distance were compared between groups. Results: Distance and time in OVX group was significantly higher than Sham group [p<0.01 and p<0.05]. Time and distance in Sham-LN group was higher in comparison with Sham group [p<0.05 and p<0.01]. There were no significant differences between OVX-LN and OVX groups in escape latency and traveled distance. Discussion: The results of present study showed that removal of ovarian hormones could impair Morris water maze tskas includiong time and distance. Administarion of non specific nitricoxide inhibitor, L-NAME, affects Morrsi water maze tasks however, its effect is different in the absence and presence of ovarian hormones but it needs to be more investigated