Olfactory bulb removal results in elevated spontaneous locomotor activity in mice

Abstract

Bilateral removal of the olfactory bulbs of female Swiss-Webster mice resulted in a striking increase in locomotor activity which remained evident even 2 1 2 months after surgery. The administration of d-amphetamine sulfate (1, 2, and 4 mg/kg) resulted in a dose dependent increase in locomotor activity but bilateral bulbectomy did not potentiate amphetamine's motor stimulant effect. The neural processes which mediate bulbectomy induced hyperactivity in the mouse are not known; however, it is clear that these processes, unlike processes involved in some other lesions which produce hyperactivity, do not interact with the locomotor facilitatory property of d-amphetamine. D-amphetamine sulfate (1, 2, and 4 mg/kg) caused a dose dependent decrease in food intake but there was no interaction between bulbectomy and the anorexic activity of d-amphetamine. The fact that bulbectomized mice display elevated locomotor activity in a nonsocial situation suggests an effect of bulbectomy upon arousal. From this perspective it is possible that many of the previously discovered social behavioral deficits produced by bulbectomy are specific manifestations of altered arousal processes.