Influence of the Cerebellar Histaminergic System on the motor and non-motor functions of mice

Abstract

The cerebellum is an important structure which participates in motor processes such as gait and balance. Currently, studies have demonstrated its involvement in cognition, emotion and learning and memory processes. Even though the histaminergic system has an important role in the neuronal circuit within the cerebellum, its mode of action is not completely understood. The histamine modulation in different body systems occurs through four types os receptors: H1, H2, H3 and H4. The results about the cerebellar histaminergic system action in the motor performance are controversial. Therefore, the aim of this study is to investigate the effects of histamine and histaminergic antagonists microinjections via cerebellar vermis, investigating a possible interaction of this system within the cerebellum in the modulation of motor and non-motor functions. The four experiments will evaluate Histamine (experiment 1), histamine H1 receptors antagonist, Chlorpheniramine (experiment 2), H2 receptors antagonist, Ranitidine (experiment 3) and H3 receptors antagonist, Thioperamide (experiment 4) effects on locomotor activity and anxiety in mice exposed to open field. In order to achieve this purpose, a 7 mm long cannula will be implanted in the cerebellar vermis through stereotactic surgery performed in male mice (Swiss Albino) weighting between 25 and 35 g. The open-field behavior test will be executed three days after surgery. The experiments will be recorded to quantify the amount of crossings (number of quadrants traversed), time spent in the central area of the arena, freezing time and number of rearings. The histologic analysis will confirm if the injection occurred appropriately in the cerebellar vermis. Statistical analysis will include the homogeneity test and analysis of variance (ANOVA), followed by Duncan's post-hoc test. (AU)