INTEGRATING BEHAVIOURAL, SLEEP AND ULTRASONIC VOCALISATION SIGNATURES IN A RAT MODEL OF PTSD USING PREDATOR ODOUR

In Post-Traumatic Stress Disorder (PTSD) sleep disturbances are among the most persistent and treatment-resistant symptoms. Disrupted sleep architecture, particularly REM sleep fragmentation, is thought to impair emotion regulation and reduce medial prefrontal cortex (mPFC) inhibition of the amygdala, promoting hyperarousal, emotional instability, attentional deficits, and memory intrusions. These daytime symptoms further degrade sleep, forming a self-perpetuating cycle. Generally, most animal models of PTSD focus on fear and anxiety symptoms with less consideration of sleep-related symptoms.
The current study developed a rodent model of PTSD by integrating predator threat exposure (PTE) with behavioural, sleep, and neurophysiological measures, alongside established risk factors including sex, early-life stress, and social isolation. Lewis rats, a high-anxious strain, underwent a conditioned predator odour threat paradigm, measuring behaviours before and after exposure. Sleep was measured using deep electrode recordings and classified into non-REM and REM sleep. Ultrasonic vocalizations were recorded, as markers of negative affect, constantly in the homecage before and after PTE exposure. Notably, there were typical 22-kHz ultrasonic vocalizations elicited during wakefulness, but these were also detected during sleep. Whether the influence of sex or stress history modulate the presence of such ‘sleep-associated alarm calls’ are currently being investigated. These findings support a multidimensional rodent PTSD model incorporating sleep and bioacoustic readouts.