The effects of chemical odors on open field approach and activity responses by male and female rats

Abstract

The effects of two purportedly attractive (butyric acid and dodecyl propionate) and two purportedly aversive (citral and isoamyl acetate) odors on aversive emotional states in male and female rats were studied. Odors were delivered in either weak or strong concentration via air-flow dilution to one-half of an enclosed chamber. Rats were tested in one of four odor sequences. All odors decreased activity after 1 min of exposure, especially in strong concentration, indicating that freezing tendencies were being enhanced. With the exception of butyric acid, novel odor increased activity after an initial 20 sec of exposure, suggesting that escape tendencies were enhanced. Butyric acid, decreased this initial activity, indicating that it may have decreased escape tendencies. However, the possibility that butyric acid facilitated onset of the freezing response is also discussed. Dodecyl propionate did not differ from the purportedly aversive odors in its effects. In addition, prior experience with other odors affected subsequent responding, suggesting a carry-over effect from previous odor exposure.