Denver Wilson (Mechanical Engineering Group at Catamount Research & Development) conducts testing with an early prototype of Med Associates’ automated bar test box for catalepsy scoring.

A Simple Apparatus for Automatically Scoring Catalepsy Behavior in Laboratory Rodents

Gerald M. Herrera, Ph.D.
Med Associates, Inc. and Catamount Research & Development, Inc.
St. Albans, Vermont USA

 

 

Background/Introduction

Catalepsy is usually defined as the state of persisting in an unusual posture, and can be a characteristic of neurological disorders such as Parkinson’s Disease and schizophrenia. In laboratory animals, catalepsy has been used for many years to investigate dopaminergic systems in the striatum. Neuroleptics, such as haloperidol, are potent cataleptogens. Several different techniques have been used to experimentally measure cataleptic behavior (Sanberg et al., 1988). The most common method for assessing catalepsy behavior has been the elevated bar test. In this test, an animal is placed with its forelimbs on bar that is elevated. Cataleptic criteria vary depending upon the study, but in most cases the amount of time that either one or both forelimbs remain on the bar is scored as cataleptic time. Haloperidol is a classic example of a potent neuroleptic that has been used as a positive control compound to experimentally induce catalepsy (e.g. Campbell et al., 1980)

In this study, we examined catalepsy scores obtained from an automated catalepsy bar test box in animals treated with haloperidol.

Methods

Male Sprague Dawley rats (230-291 grams) were used in this study.  Rats were injected with haloperidol (0.25 to 1.5 mg/kg, i.p.)or vehicle (1:1 ethanol:0.9 % NaCl).  One hour later, rats were placed into an ENV-003 Rat Catalepsy test chamber (Med Associates, Inc.) with their two forelimbs on a stainless steel rod (0.5 inch diameter) elevated 3.6 inches from the chamber floor.  The hindlimbs were in contact with the solid stainless steel floor of the chamber.  An electrical circuit connected the elevated bar with the chamber floor.  The electrical circuit was completed while at least one forelimb remained attached to the elevated bar.  The current flowing through this circuit is small enough such that it is imperceptible to the animal (~0.3 µA).  Med PC software running custom Med State Notation for Catalepsy (SOF-700RA-19, Med Associates, Inc.) was used to record experimental data.  The computer stored the amount of time that at least one of the rat’s forelimbs remained attached to the elevated bar.  When both of the rats forelimbs came off the elevated bar, the electrical circuit was broken and the computer timer stopped counting.  Three trials were run in each rat, with subsequent trials started as soon as the previous trial ended.  Catalepsy times for each trial were averaged, yielding a single catalepsy time for each animal at each concentration of haloperidol (or vehicle).  Results are expressed as mean ± SEM, and catalepsy scores were compared by one-way ANOVA followed by Student Newman-Keuls Multiple Comparison Test.

Results/Discussion

Haloperidol dose-dependently increased catalepsy times (Figure 1).  In vehicle treated animals, catalepsy time was 1.6 ± 0.2 sec (n=6).  In rats treated with 0.5 mg/kg haloperidol, catalepsy time was significantly increased to 28.3 ± 7.2 sec (n = 6; p<0.05).  In rats treated with 1.5 mg/kg haloperidol, catalepsy time was increased by 118.9 ± 1.2 sec (n=6; p<0.05). 

	Figure 1 – Haloperidol dose-dependently increases catalepsy time in rats.  N=6 per concentration of haloperidol, or vehicle.

The ENV-003 Catalepsy Test Chamber is a convenient apparatus for automating catalepsy scoring.  This chamber can be used with both rats and mice.  The chamber features a removable bar that can be positioned at any one of eight heights, ranging from 1.7” from the chamber floor up to 8.7” from the chamber floor.  This flexibility allows for the use of animals of different sizes (mice to rats), as well as placing animals in various positions.  Also, the catalepsy chamber contains four different contact rods ranging in diameter from 3/16” up to ½”.  Again, this flexibility allows for the use of both mice and rats, as well as animals of different sizes within a given species.

References

Campbell, A., Herschel, M., Cohen, B.M., and Baldessarini, R.J.  Tissue levels of haloperidol by radioreceptor assay and behavioral effects of haloperidol in the rat.  Life Sciences 27: 633-640, 1980.

Sanberg, P.R., Bunsey, M.D., Giordano, M., and Norman, A.B.  The catalepsy test: its ups and downs.  Behavioral Neurosci 102: 748-759, 1988.