An Open Source Automated Bar Test for Measuring Catalepsy in Rats

Abstract

Catalepsy bar tests are widely used to measure the failure to correct an imposed posture resulting from muscular rigidity. Procedures for measuring catalepsy vary greatly in the published literature, but one commonly used test measures the time it takes for a rodent to remove one or both of its forelimbs from a bar. The following paper describes an affordable, adjustable, open-source bar test that automatically measures and logs the time it takes for a rat to remove itself from a bar. While commercially available automated bar tests are prohibitively expensive, requiring proprietary software and hardware to operate, the proposed apparatus runs on an Arduino-based microcontroller making it low-cost and customizable. This 3D-printed design costs less than 65 United States dollars to build and is simple to assemble and operate. The beam-break sensor design also eliminates many of the pitfalls of the "complete-the-circuit"-based approach to recording catalepsy. The paper further describes the successful validation of the design using adult male rats injected with different doses of haloperidol to demonstrate a dose-dependent cataleptic effect. This design provides a versatile, low-cost solution to standardizing and automating measurement of catalepsy in rodents.

Keywords: antipsychotic; automated; catalepsy; open source.

Graphical abstract

Figure 1.

3D printed, automated catalepsy bar test (A), diagram of a rat in the bar test (B), and circuit schematic for automated bar test assembly (C).

Figure 2.

Mean time spent on catalepsy bar in seconds as measured by the apparatus in adult male rats. Error bars represent SEM; *p < 0.0001 compared with vehicle; #p < 0.01 compared with 1 mg/kg dose. Raw data included as Extended Data Figure 2-1.