A Versatile, Behavioral Method to Investigate Thyroid Hormone Effects on Cerebellar Function

To comprehensively understand the various facet of thyroid hormone development in the central nervous system, we investigated a spectrum of perspectives, spanning behavior phenotype to molecular direction at the single-cell level. We are also looking on connecting those different dimension of the patient to elucidate the mechanism of thyroid hormone in brain development. The mainstream research in our field primarily centers around the molecular biology with numerous researchers investigating the impact of thyroid hormone on gene expression.

Nowadays, there are increasing focus on behavior analysis to uncover the role of thyroid hormones, particularly within the central nervous system. This approach could explain the specific behaviors of observed in certain thyroid hormone-related diseases. With the current level of available techniques such as the rotarod test, researchers often struggle to access behavioral patterns, especially motor performance, in model mice.

This hinders the translation of research to clinical situations. Our protocol has been designed to assess thorough motor alteration in mice, facilitating a clear interpretation of behavior observations. Begin by setting up the ladder assembly for the ladder beam test.

After connecting the four parallel plexiglass containing the holes, proceed to design the various kinds of ladder rungs by inserting aluminum sticks into the holes on the plexiglass. For the horizontal ladder test, insert aluminum sticks into the holes on the plexiglass walls. For the zigzag ladder test, insert the aluminum sticks into every third hole in the horizontal and vertical directions on the plexiglass walls.

In both cases, adjust the widths of the ladder rungs as required by widening or narrowing the distance of the plexiglass walls. Then place the dark chamber in the target site to motivate the animals to move toward the goal. Finally, place the cushion under the ladder rungs for safety.

Before subjecting the mouse to the ladder beam test, perform an initial habituation training on the completely assembled ladder beam test apparatus. To do so, place the mouse at the edge of the ladder designated as the starting point. Using an air puff, encourage the mouse to move forward on the ladder rung towards the goal.

Repeat the training until the mouse gets habituated to walk on the ladder rungs. To perform the motor performance test, place the already habituated mouse at the starting point. Record the time the animal takes to cross the ladder, and count the number of foot slips occurring when the mouse fails to place its paws or slips after placing paws on the aluminum sticks.

Calculate the average value of time and foot slips per day, and compare the average values between the different animal groups. Both horizontal and zigzag ladder beam tests detected robust impairment in motor coordination in MF-1 mice. They spent a significantly longer time crossing the ladder, as well as made more foot slips when compared to wild type mice.

More importantly, the scores did not improve after three days in MF-1 mice, whereas wild type mice showed improvement in that period. There was no change in grip strength between wild type and MF-1 mice.