Responses to positive and aversive stimuli in estrous female rats housed in a seminatural environment: Effects of yohimbine and chlordiazepoxide.

The behavioral effects of putative anxiolytic and anxiogenic drugs are usually evaluated in highly standardized tests. Here, we determined the effects of such drugs in rats housed in mixed sex groups in a seminatural environment. Sexually receptive female Wistar rats were treated with either the anxiolytic drug chlordiazepoxide (2 mg/kg), the anxiogenic drug yohimbine (1 mg/kg), or saline (1 ml/kg). Different emotional challenges eliciting purportedly positive affect (lavender odor, Mozart's music, chocolate flavored food) or negative affect (white noise, fox odor) were then introduced into the seminatural environment. A co-occurrence analysis revealed that music was rather aversive to the rats, as were white noise and fox odor. Lavender and chocolate exposure decreased classical indicators of fear. White noise suppressed sexual behaviors and caused avoidance of the open area. Yohimbine increased sexual receptivity during lavender exposure, decreased the latency to flee the white noise, and increased self-grooming regardless of the emotional challenge. Chlordiazepoxide was effective only during exposure to white noise, and increased the frequency of hiding alone. The modest effects of the drugs in the seminatural environment may be the result of social buffering and rats experiencing a high degree of controllability over their environment.

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