Elevated plus maze behavior, auditory startle response, and shock sensitivity in predisease and in early stage autoimmune disease MRL/lpr mice

Behaviors indicative of anxiety have been suggested to emerge with the onset of autoimmune disease in MRL/MpJ-Fas(lpr) (MRL/lpr) mice. This study extends the behavioral characterization of MRL/lpr and congenic MRL/MpJ+/+ (MRL/+) mice using the elevated plus maze (EPM), acoustic startle response, and foot-shock sensitivity tasks. In the elevated plus maze, predisease MRL/lpr mice exhibited less anxiety while MRL/lpr mice in the early stage of autoimmunity did not differ from age-matched control MRL/+ mice. MRL/lpr mice exhibited lower startle responses compared to MRL/+ mice. Similarly, predisease MRL/lpr mice were less reactive to various foot-shock levels than MRL/+ mice. Both the MRL/lpr and the MRL/+ strains exhibited startle habituation deficits, implicating the background MRL strain in the impairment in this process. These data do not support the hypothesis that increased anxiety is apparent with the emergence of autoimmune disease in MRL/lpr mice; however, anxiety may appear as the disease advances. (C) 2001 Elsevier Science (USA).