Histamine is a neurotransmitter in the central nervous system. The cell bodies of histaminergic neurons are present in the posterior hypothalamus, in the tuberomammillary nucleus, with fibers projected to several structures of the central nervous system, such as the cerebellum. The cerebellum has been classically related to motor coordination, working on learning of neural activity patterns to perform movements and tasks. Recent works have shown that the cerebellar histaminergic system has also a role in emotional memory consolidation. In this study, the aim is to investigate the dose-dependent effects of intra cerebellar microinjections of histamine on motor performance and motor learning of mice, and then correlate the role of the histaminergic system in the cerebellum in motor and non- motor functions. For this purpose, we will use a balance beam test. The cerebellar vermis of male mice will be implanted with guide cannulae, and after three days of recovery, the test will be performed. Immediately after a habituation session, animals will receive microinjection of salina or histamine, in doses of 0.54 nmol, 1.36 nmol, 2.72 nmol, and 4.07 nmol/ 0.1 microliter. The tests will be recorded to quantify latency and the number of errors on the beam. Histology will confirm if mice had accurate cannula placement in the cerebellar vermis. Statistical analysis will include the homogeneity test and analysis of variance (ANOVA) followed by post hoc test of Duncan.
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