Pica behavior induced by body rotation in mice.

OBJECTIVES

To study whether rotational stimulus induced pica and whether the vestibular apparatus was necessary for obtaining rotation-induced pica in mice.

METHODS

Pica behavior in mice was investigated following 60 min of rotation once daily at 70 rpm (15 s on with 5 s off) for 3 consecutive days. After evaluating vestibular function and histology of vestibular epithelia, we examined rotation-induced kaolin intake, so-called pica, in sham-lesioned and chemically labyrinthectomized mice.

RESULTS

The labyrinthectomized mice exhibited loss of the contact righting and swimming capability while the destruction of hair cells of vestibular epithelia was observed. Moreover, mice subjected to rotation, but not labyrinthectomized mice, showed a significant increase in kaolin intake at the last 2 rotation sessions and the first postrotation session.

CONCLUSIONS

The findings indicated that a functioning vestibular system is necessary for rotation-evoking pica in mice and thus pica can be a behavioral index of motion sickness in mice.