An automated rotarod method for quantitative drug-free evaluation of overall motor deficits in rat models of parkinsonism

doi:10.1016/S1385-299X(97)00034-2

Brain Research Protocols

Volume 2, Issue 1, 1 December 1997, Pages 75-84

https://doi.org/10.1016/S1385-299X(97)00034-2 Get rights and content

Abstract

A variety of tests have been proposed for evaluation of motor deficits in rat models of hemiparkinsonism. The most widely used test, the “rotational behaviour” test, is based upon motor asymmetry induced by drug administration, leading to problems of sensitization, conditioning and priming. In addition, lesion-induced rotational behaviour is sometimes overcompensated by treatments (grafts) while other deficits are unaffected. However, rotational behaviour is reproducible and easy to quantify. On the contrary, most drug-free tests have proved of limited applicability because of subjective scaling, excessive interaction between the experimenter and animals, motivational effects, excessively complex tasks, etc., making it difficult to compare results from different laboratories. In this paper, we present a rotarod based method for automated drug-free evaluation of overall motor deficits in the rat model of hemiparkinsonism, and for identifying treatment-induced changes. Animals are pre-trained on the rotarod and then tested at a series of increasing rod speeds; from this set of values a unique score for each animal is computed (the overall rotarod performance, ORP) summarizing its performance at different speeds. This value is easy to compute and greatly simplifies statistical comparisons. Major advantages of the test are: (i) it does not require drugs, but is nevertheless highly objective, reproducible and easy to quantify; and (ii) falling of animals from rotating rod seems to depend on a combination of lesion-induced deficits which become more evident when rats are forced to move at faster speeds. Since the test is not based exclusively on motor asymmetry, it may also be useful for characterization of bilaterally lesioned animals, for which drug-induced rotational behaviour tests cannot be used.

Section snippets

Type of research

This protocol may be of value for research in the following areas:

•
Motor effects of dopamine system lesions [21].
•
Evaluation of pharmacological therapies for Parkinson's disease (PD).
•
Effects of grafts on PD models [21].
•
Evaluation of motor deficits induced by selective brain lesions and/or traumatic brain injury [11].
•
Aging-induced changes in motor performance 9, 10.
•
Comparative actions of muscle relaxation agents 13, 19.

Time required

The time required for the test depends on the number of speeds (NS) to be tested, the relationship between the number of rats (R) and lanes available (L) and the cut-off time (Tc), together with the desired rest period between consecutive tests (Tr). Total time for one session may then be calculated as: total time=NS·(R/L)·(Tc+Tr). For instance, testing of eight animals in a 4-lane automated rotarod, using the protocols described in this paper, requires 300 s at each speed (Tc=300, no

Materials

Adult (250–300 g) female Sprague–Dawley rats (Letica, Barcelona, Spain) were used. All experiments were carried out in accordance with the European Communities Council Directive of 24 November 1986 (86/609/EEC).

Detailed procedure

In the procedure described in what follows, a CR-1 Rotamex system (see above) was used. However, the procedure could be easily adapted for other rotating roller systems.

General considerations

The maximal value of ORP depends on cut-off time chosen and the maximal rod speed used. If a 300 s test is chosen and 40 r.p.m. is the maximal speed, the maximum ORP score possible is 10 500, regardless of the interval between consecutive speeds. Apparently anomalous results, e.g. an animal falls off the rod at 10 r.p.m. but remains on the rod for the 300 s at higher speeds, have a minimal effect if enough rod speeds are considered. For example, a “0” score at any intermediate speed in a 10,

Animal training

As stated above, training of animals involves teaching the task and reducing handling stress. In the present study, normal animals learnt the task very quickly and did not forget it for a long period, even after lesions and lesion-and-grafting treatments over 5 months later [21]. The second part of training is aimed at reducing the interaction between the operator and animals, thereby reducing handling stress. Training to reduce stress is important, since stressed animals may show abnormally

Training of animals

Animals underwent at least one training session.

•
7.1.1. Teach the task to animals (i.e., remaining on the rod until it stops).
•
7.1.2. Habituate animals to the handling involved in the test.
•
7.1.3. Familiarize researcher with the whole protocol.

Animal testing

After training, animals are subjected to pre-treatment rotarod testing, as follows:

•
7.2.1. Transfer the animals to the rotarod room, with lights off, at least 15 min before beginning the test.
•
7.2.2. Create rotarod unit control files (i.e., pre-set test

Essential literature references

Original papers: 6, 12, 21, 25.

Acknowledgements

We thank Professors J.L. Otero and M. Cadarso (Department of Statistics, University of Santiago de Compostela, Spain) for critical review of the manuscript. This study was supported by the Spanish CICYT and XUGA.

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ProtocolAn automated rotarod method for quantitative drug-free evaluation of overall motor deficits in rat models of parkinsonism

Abstract

Section snippets

Type of research

Time required

Materials

Detailed procedure

General considerations

Animal training

Training of animals

Animal testing

Essential literature references

Acknowledgements

Neuroscience

Brain Res.

J. Am. Pharmacol. Assoc.

Brain Res.

Brain Res.

Brain Res. Bull.

Prog. Neuro-Psychopharmacol. Biol. Psychiatry

Neurobiol. Dis.

Pharmacol. Biochem. Behav.

Pharmacol. Biochem. Behav.

J. Pharmacol. Meth.

Brain Res.

Brain Res.

Protocol
An automated rotarod method for quantitative drug-free evaluation of overall motor deficits in rat models of parkinsonism