Blockade of D 1 -type dopaminergic receptors corrects passive avoidance performance in gonadectomized male rats

Abstract

The purpose of the present work was to devote the comparative analysis of agonist and antagonists of D 1 -dopaminergic receptors effects on passive avoidance learning in male rats with imbalance of androgens. Methods. Experiments were carried out on albino male rats of Wistar line (n = 180, 180—200 g). Gonadectomy of male rats was performed using standard method. Two weeks following surgery all behavioral tests were conducted. Experiments were made on intact, gonadectomized (GDX) and GDX male rats treated with low dose of testosterone propionate. The effects for chronic administration of agonist of D 1 -type dopaminergic receptors — SKF-38393 (0,1 mg/kg, i.p.) and antagonist of D 1 -type dopaminergic receptors — SCH-23390 (0,1 mg/kg, i.p.), as well as its combination with low dose of testosterone propionate (0,5 mg/kg, s.c.) during 14 days on behavioral processes were tested in the passive avoidance paradigm and the «open field» test. Statistical analysis was performed using one-way ANOVA test followed by Newman-Keuls post-hoc test. Results. Co-administration of SCH-23390 with low dose of testosterone propionate completely restored impaired passive avoidance performance in GDX males. Moreover, GDX rats treated with SCH-23390 plus low dose of testosterone propionate demonstrated increased exploratory and grooming behavior in the «open field» test. Both SKF-38393 alone and in combination with low dose of testosterone propionate markedly impaired passive avoidance learning and failed to modify behavior in the «open field» test in GDX rats. Conclusion. The results of the present study suggest that chronic treatment with SKF-38393 (stimulation of D 1 -type dopaminergic receptors) significantly impairs capability of GDX rats to formation of passive avoidance performance. Moreover, its combination with testosterone propionate resulted in blockade of positive effect for testosterone propionate on passive avoidance learning. Chronic administration of SCH-23390 (blockade of D 1 -type dopaminergic receptors) markedly improves passive avoidance performance in GDX rats. Also, the combined treatment with SCH-23390 and testosterone propionate completely corrects passive avoidance learning in GDX male rats.