Disturbed emotionality in autoimmune MRL-lpr mice.
MRL-lpr mice develop symptoms of autoimmune lupus-like disease early in the life and MRL(-)+/+ mice develop it substantially later. The present study examines our previous suggestion that autoimmune MRL-lpr mice show altered emotional reactivity. In addition, it aims to identify the set of measures which best discriminate the behavior of MRL-lpr mice from their congenic controls (MRL +/+). Behavior of males from these two substrains (n = 40/substrain; 3-4 mo of age) was compared on a battery of tests presumed to be reflective of emotional reactivity. MRL-lpr mice explored the open field less, spent more time at home-base, and defecated less in comparison to congenic MRL +/+ controls. Moreover, MRL-lpr mice hesitated to step down from an elevated platform and to make contact with a novel object. They also visited open-arms of a plus-maze less often and showed extensive floating in the Porsolt's swim test. Discriminant analysis revealed that the performance of the MRL-lpr and MRL +/+ mice differed most profoundly on measures taken in the Porsolt's swim and step-down tests. In addition, in the MRL-lpr group high titers of serum antinuclear antibodies were associated with impaired exploration of a novel object. These results are consistent with the previously proposed notion of increased "timidity" in autoimmune MRL-lpr mice and of an immune factor contribution to altered emotional reactivity. Considering that behavior of autoimmune MRL-lpr mice resembles behavior of stressed animals, it is speculated that disturbed emotional reactivity reflects the effect of autoimmunity on the hypothalamic-pituitary-adrenal axis.
Sakić
B
B
Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
Szechtman
H
H
Talangbayan
H
H
Denburg
S D
SD
Carbotte
R M
RM
Denburg
J A
JA
D000818:Animals; D001143:Arousal / Q000502:physiology*; D001327:Autoimmune Diseases / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology; D004644:Emotions / Q000502:physiology*; D005239:Fear / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D009043:Motor Activity / Q000502:physiology