Journal of Neuroscience Methods 177 (2009) 317–321 Contents lists available at ScienceDirect Journal of Neuroscience Methods journal homepage: www.elsevier.com/locate/jneumeth The footfault test as a screening tool in the 6-hydroxydopamine rat model of Parkinson’s disease Roberta Bristot Silvestrin a,1 , Lucas Fürstenau de Oliveira b,2 , Cristiane Batassini a,1 , Alcyr Oliveira c,3 , Tadeu Mello e Souza d,∗ a Programa de Pós-Graduac ¸ão em Neurociências – ICBS, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite, 500, Sala 107, CEP 90.046-900, Porto Alegre, RS, Brazil b Complexo de Ensino Superior de Cachoeirinha, Silvério Manoel da Silva, 160, Colinas 94940-243, Porto Alegre, RS, Brazil c Universidade Federal de Ciências da Saúde de Porto Alegre, Departamento de Saúde Coletiva, Rua Sarmento Leite, 245 Centro 90050-170, Porto Alegre, RS, Brazil d Departamento de Bioquímica – ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 – anexo CEP 90035-003, Porto Alegre, RS, Brazil article info Article history: Received 8 February 2008 Received in revised form 19 September 2008 Accepted 15 October 2008 Keywords: Parkinson 6-Hydroxydopamine Footfault Rat Screening abstract The administration of 6-hydroxydopamine (6-OHDA) into the nigrostriatal pathway is a rat model of Parkinson’s disease (PD). The footfault test is a behavioural task in which rodents have their motor func- tions assessed. Here, we observed that unilaterally 6-OHDA-lesioned animals show a context-induced ipsilateral rotational behaviour when placed on the footfault apparatus for 3 min and this may be used as index to detect lesioned animals. Our results showed a sensitivity and specificity of 100% for lesions higher than 94% and 64%, respectively (ROC curve: AUC = 0.988). A binary logistic regression model showed an exp B = 1.116 (95% CI, 1.007–1.236) and C = -9.081 ± 4.554 (p = 0.046) using the nigral tyrosine hidroxylase immunocontent as standard (each unit represents a 10%-lesion extension). Additionally, the footfault test was more sensitive than apomorphine challenging at 1mg/kg when these tests were carried out days apart and it was less sensitive than methylphenidate at 40mg/kg (sign test, p < 0.05). Therefore, the foot- fault test may be very useful in the PD animal model for screening animals since it is fast and simple and it does not require a drug to induce rotational activity. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Animal models of disease provide useful and indispensable tools for studying causes, symptoms, and other physiological features involved in pathological processes. Additionally, behavioural tests give us indirect information on the state of cognitive and locomotor systems. The administration of 6-hydroxydopamine (6-OHDA) into the rat substantia nigra, medial forebrain bundle, or striatum leads to a depletion of dopamine in the basal ganglia (Hefti et al., 1980; Yuan et al., 2005). This effect mimics the dopaminergic depletion observed in Parkinson’s disease (PD) conferring to the rat model a solid construct and predictive value (Deumens et al., 2002). Several behavioural tests can be applied to assess different symptoms and deficits in the model, such as the reaction-time test, ∗ Corresponding author. Tel.: +55 51 33085570. E-mail addresses: betasilvestrin@yahoo.com.br (R.B. Silvestrin), luke@ufrgs.br (L.F. de Oliveira), cris.batassini@terra.com.br (C. Batassini), Alcyr.oliveirajr@gmail.com (A. Oliveira), tmelloesouza@yahoo.com.br (T.M. Souza). 1 Tel.: +55 51 33083092; fax: +55 51 33083092. 2 Tel.: +55 51 34418650. 3 Tel.: +55 51 33038826. the paw retraction time test, the bar-pressing task, the staircase test, forelimb asymmetry, the narrow beam test (Deumens et al., 2002), somatosensory neglect (Castaneda et al., 2005), and the foot- print analysis (Metz et al., 2005). When animals are unilaterally lesioned, they present rotational activity after challenging with a dopamine-acting drug, such as amphetamine, apomorphine, and more recently, methylphenidate (MP) (Ungerstedt and Arbuthnott, 1970; Chopin et al., 1999). This drug-induced rotational activity (DIRA) is usually considered as index to infer dopamine depletion (Ungerstedt and Arbuthnott, 1970; Hefti et al., 1980). However, drug challenging demands a long session and also induces long-term biochemical changes (Morelli et al., 1989). Here we present a 3- min and drug-free test for screening unilaterally lesioned animals in the 6-OHDA PD model. The footfault test is a behavioural task employed to verify the animal’s ability to place its paws during the exploration of an ele- vated grid (Hernandez and Schallert, 1988; Starkey et al., 2005). The test has been used in animal models of ischemic injury (Modo et al., 2000; Pitsikas et al., 2001; Lubics et al., 2005), spinal cord lesion (Himes et al., 2006), and pyramidotomy (Starkey et al., 2005). Although the main concern in these cases was to observe the asym- metry of foot failure from inaccurate paw placement leading to slipping through the grid, the footfault test has potential use in the 0165-0270/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jneumeth.2008.10.030