The effects of injection of Amlodipine and Steroid Hormone into Hippocampus on Motor Skill Learning and Motion balance in the rats

Background and Aim : The durable memory makes motor skill learning an interesting paradigm for the study of learning and memory mechanisms and experiments showed blocking the calcium channels affecting memory and learning. So in the present study, the effect of Calcium Dihydropyridine antagonist and steroid hormones and their interaction in the motor skill learning and balance consolidation was investigated. Amlodipine (calcium dihydropyridine antagonist) by blocking the calcium channels of the nerve cells and affecting the synapses have a different effect on memory and learning. The steroids have a protective function on the central nervous system, steroid hormones with Amlodipine were used for a wider study.Methods : In this experimental study, twenty-five mature wistar rats weighing 250±25g were randomly divided into the 5 following groups (n=5 rats/group): Control, the groups received Amlodipine (3μl), Amlodipine plus Estradiol (2μl+1μl), Amlodipine plus Progesterone (2μl+1μl) and Amlodipine plus Estradiol plus Progesterone. Before surgery, the rats motion balance was examined with the rotarod set. The rotarod test is widely used to evaluate the motor coordination of rodents, and is especially sensitive in detecting cerebellar dysfunction. However, this test can be used to study motor skills learning. Animals in the control groups did not receive any drug. Rats in the drug groups were anesthetized with intra-peritoneal injection and bilateral cannulas were implanted 0.2 mm above hippocampus, by stereotaxic apparatus. A week after the surgery, the drugs were injected into the groups through cannulas in final volume of 3μl. To check the learning and memory criteria, at the end of injection, motor skill learning were assessed by rotarod tests (1,3 and 24 hours after the injection, because Successful learning of a motor skill requires repetitive training). The test measures parameters such as riding time (seconds) or endurance. One-way analyses of variance (ANOVA) followed by Tukey’s post hoc test, were used for analysis of the data.Results : The collected information from pharmaceuticals showed that intra-hippocampus administration injection of Amlodipine, significantly (p<0.01) reduced rotarod test parameters. Also, 3h after the injection of Amlodipine plus estrogen, the results of the rotarod test in this group are significantly(p<0.01) higher than Amlodipine plus E2+P4 and Amlodipine plus P4 drug groups. The comparison of the rotarod test of each group suggests that the motor skill and balance index in the control group has significantly(p<0.01) increased in the1,3,24 hours after injection. The rotarod test of drug groups with respect to the pre -injection drug rotarod test showed a significant decrease at the level(p<0.001). However, in the Amlodipine plus estrogen medication group, 3 hours after the injection, a significant increase was observed relative to the rotarod test before drug injection.

Keywords:

Amlodipine , Steroid Hormones , Learning , Balance , Motor Skill Learning , Rat