Maternal separation of rat pups is an ethopharmacologically validated model of anxiety and is measured by the duration and frequency of ultrasound vocalizations (USVs) made by the pups during this separation. These cries occur between 35 and 45 kHz, and have been described as "distress vocalizations" or "isolation calls".
In this article we describe the use of UltraVox in order to record the USVs of groups of 8 rat pups under conditions of relatively high and low stress, and consequently prepare the background under which potential anxiolytic or arousing/anxiogenic activity of novel compounds may be assessed. We report that this model is sensitive to clinically active anxiolytics such as diazepam (Valium®), as well as buspirone (Buspar®). This model is also sensitive to the anxiogenic activity of beta carbolines such as FG7142.