Effects of Injections of Pramipexole and steroid Hormones in to Hippocampus on motor skill learning in rats

Background and Aim : Dopamine (DA) plays a key role in motor performance, motor skill learning, and motor cortex synaptic plasticity.In recent years, many studies have shown that different dopamine agonists have different effects on motor skill memory. Pramipexole is a dopamine agonist and Used to treat Parkinson s disease. It binds to presynaptic and postsynaptic dopamine D2 and D3 receptors but has the highest affinity for the dopamine D3 receptor subtype. By activating mediator neurons or in steroid environment, neurotransmitters produce different physiological effects. Therefore, the aim of this study was to determine the effects of co-injection of Pramipexole and steroid Hormones in to Hippocampus on motor skill learning in rats.Methods : In this experiment, twenty Male Wistar rats weighing 200-250 g were randomly divided into the 4 following groups (n=5 rats/group): control, pramipexole (2μl), pramipexole (2μl) along with estradiol (1μl) and Pramipexole (2μl) plus progesterone (1μl) .fixed speed rotarod test used for evaluation of motor skill learning after 1,3 and 24 hour of injection . The latency to falling was compared and analyzed. One-way analyses of variance (ANOVA) followed by Turkey s post hoc test, were used for analysis of the data.Results : The collected data showed that intra-hippocampal injection of Pramipexole significantly decreased latency to falling after1and 3 hour of injection (p<0.05). Also, co-injection of Pramipexole and steroid Hormones significantly reduce motor skill learning in 1 and 3 hour after injection (p<0.001) and the latency to falling was significantly increased 24h after injection compared to previous time(p<0.001). The information that collected in 24 hour after injection showed that there is no significant difference between experimental group (p> 0.05).Conclusion : These results revealed a significant decrease in the motor skill learning by pramipexole but it has not long-duration effects. Also there is an interaction between pramipexole and steroid hormones in modulating of motor skill learning.

Keywords:

Pramipexole , Estradiol , progesterone , motor skill learning , rotarod