Home cage and open-field locomotor activity responses in singly housed olfactory bulbectomised rats

Behavioural hyperactivity is one of the most studied consequences of olfactory bulbectomy in rats. Attenuation of this hyperactivity in an arena such as the open-field is an indicator of antidepressant activity. However, this response can only be measured at one timepoint because of habituation. We examined an alternative method of detecting locator activity, the home cage activity response, and found that singly housed olfactory bulbectomised (OB) rats exhibited an enhanced nocturnal hyperactivity 2 weeks following surgery. Moreover, single housing produced a typical hyperactive response in the open-field which was qualitatively similar to that previously observed when OB rats are group housed. A reduction in body weight was observed in OB rats throughout much of the first week following surgery when compared with shams. Food and water intake were similarly reduced in both groups in the days immediately following surgery. Thus, this study confirms that the behavioural hyperactivity in the open-field is intact following single housing and that home cage activity is a viable alternative for measuring hyperactivity in OB rats that has the advantage that such activity can be repeatedly measured without the appearance of habituation.