Customizable Open-Source Rotating Rod (Rotarod) Enables Robust Low-Cost Assessment of Motor Performance in Mice

KCTD1 regulation of Adenylyl cyclase type 5 adjusts striatal cAMP signaling

Dopamine transfers information to striatal neurons, and disrupted neurotransmission leads to motor deficits observed in movement disorders. Striatal dopamine converges downstream to Adenylyl Cyclase Type 5 (AC5)-mediated synthesis of cAMP, indicating the essential role of signal transduction in motor physiology. However, the relationship between dopamine decoding and AC5 regulation is unknown. Here, we utilized an unbiased global protein stability screen to identify Potassium Channel Tetramerization Domain 1 (KCTD1) as a key regulator of AC5 level that is mechanistically tied to N-linked glycosylation. We then implemented a CRISPR/SaCas9 approach to eliminate KCTD1 in striatal neurons expressing a Förster resonance energy transfer (FRET)-based cAMP biosensor. 2-photon imaging of striatal neurons in intact circuits uncovered that dopaminergic signaling was substantially compromised in the absence of KCTD1. Finally, knockdown of KCTD1 in genetically defined dorsal striatal neurons significantly altered motor behavior in mice. These results reveal that KCTD1 acts as an essential modifier of dopaminergic signaling by stabilizing striatal AC5.

The time-dependent changes in a mouse model of traumatic brain injury with motor dysfunction

Traumatic brain injury (TBI) results from sudden accidents, leading to brain damage, subsequent organ dysfunction, and potentially death. Despite extensive studies on rodent TBI models, there is still high variability in terms of target points, and this results in significantly different symptoms between models. In this study, we established a more concise and effective TBI mouse model, which included locomotor dysfunctions with increased apoptosis, based on the controlled cortical impact method. Behavioral tests, such as elevated body swing, rotarod, and cylinder tests were performed to assess the validity of our model. To investigate the underlying mechanisms of injury, we analyzed the expression of proteins associated with immune response and the apoptosis signaling pathway via western blotting analysis and immunohistochemistry. Upon TBI induction, the mouse subjects showed motor dysfunctions and asymmetric behavioral assessment. The expression of Bax gradually increased over time and reached its maximum 3 days post-surgery, and then declined. The expression of Mcl-1 showed a similar trend to Bax. Furthermore, the expression of caspase-3, ROCK1, and p53 were highly elevated by 3 days post-surgery and then declined by 7 days post-surgery. Importantly, immunohistochemistry revealed an immediate increase in the level of Bcl-2 at the lesion site upon TBI induction. Also, we found that the expression of neuronal markers, such as NeuN and MAP2, decreased after the surgery. Interestingly, the increase in NFH level was in line with the symptoms of TBI in humans. Collectively, our study demonstrated that the established TBI model induces motor dysfunction, hemorrhaging, infarctions, and apoptosis, closely resembling TBI in humans. Therefore, we predict that our model may be useful for developing effective treatment option for TBI.

Pros and cons of narrow- versus wide-compartment rotarod apparatus: An experimental study in mice

The rotarod test, a sensorimotor assessment that allows for quantitative evaluation of motor coordination in rodents, has extensive application in many research fields. The test results exhibit extreme between-study variability, sometimes making it challenging to conclude the validity of certain disease models and related therapeutic effects. Although the variation in test paradigms may account for this disparity, some features of rotarod apparatus including rod diameter make differences. However, it is unknown whether the width of animal compartment has a role in rotarod performance. Here we comprehensively evaluated the active rotarod performance and adverse incidents in multiple strains of mice on an 11-cm- or a 5-cm-wide compartment apparatus. We found that mouse behaviors on these apparatuses were surprisingly different. It took a markedly longer time to train mice on the narrow- than wide-compartment rotarod. Further, non-transgenic B6129S and tau knockout mice aged 11 months and beyond showed different levels of improvement based on the compartment width. These mice had no overt improvements on accelerating rotarod over 4-5 training sessions on the narrow compartment, contrary to marked progress on the wide counterpart. The incidents of mice passively somersaulting round and fragmented running occurred significantly more on the wide than narrow compartment during accelerating rotarod sessions. Mice fell off rod more frequently on narrow than wide compartments upon attempt to turn around and when moving backward on rod. The pros and cons of narrow versus wide compartments are informative as to how to choose a rotarod apparatus that best fits the animal models used.