[Chronic administration of RJR-2403 in combination with low-dose of 17beta-estradiol corrects passive avoidance...

The aim of this work was to study the effect of stimulation or blockade of Na7-cholinoreceptors with a low dose of 17beta-estradiol on the passive avoidance performance and behavior in the open-field test in adult ovariectomized (OVX) female rats. Agonist of Na7-cholinoreceptors RJR-2403 (1.0 mg/kg, i.p.) or antagonist of Na7-cholinoreceptors mecamylamine (1.0 mg/kg, i.p.) treated chronically (14 days) alone and in a combination with low dose of 17beta-estradiol (0.5 microg/rat, s.c.) to OVX rats. Co-administration of RJR-2403 with low dose of 17P-estradiol completely restored impaired passive avoidance performance in OVX females. OVX rats treated with RJR-2403 and low dose of 17beta-estradiol demonstrated increased exploratory and grooming behavior in the open-field test. Both mecamylamine alone and in combination with low dose of 17beta-estradiol failed to influence the passive avoidance learning and failed to modify behavior in the open-field test in OVX rats. The results of the present study suggest positive effect of RJR-2403 in combination with low dose of 17beta-estradiol on passive avoidance learning at estrogen deficiency.