Predator odour but not TMT induces 22-kHz ultrasonic vocalizations in rats that lead to defensive behaviours in conspecifics upon replay

Abstract

Predator odours induce defensive behaviour in prey animals such as rats. The present study investigated (1) whether laboratory rats exposed to predator odours emit 22-kHz calls which may have an alarming function and (2) whether playback of such calls induces behavioural changes in conspecifics. For this, Sprague-Dawley rats were exposed to samples of fox and lion urine, as well as to the synthetic predator odour TMT. Despite that all odours induced defensive behaviour, only predator urine samples but not TMT were able to induce 22-kHz calls in a few rats. In a second experiment, naive rats were exposed to playback presentations of the 22-kHz calls recorded in the first experiment, as well as to phase-scrambled and frequency-shifted control stimuli. Low intensity playback presentations led to a reduction of locomotor activity during the presentation of the 22-kHz calls but not of the control stimuli. This effect was less specific under high intensity conditions. Taken together the present findings show that natural predator odours are able to induce emission of 22-kHz calls in rats and support the hypothesis that these calls have an alarming function.

22 kHz and 55 kHz ultrasonic vocalizations differentially influence neural and behavioral outcomes: Implications for modeling anxiety via auditory stimuli in the rat

“…an aggressive intruder; , though the nuance and meaning of these are not yet well characterized. Conversely, rats reliably emit 22kHz USVs across a variety of fearful and anxiety-provoking situations, some of which include: restraint stress (Reed et al, 2013), swim stress (Drugan et al, 2013), chronic variable stress (Mällo et al, 2009), predator odor/exposure (Blanchard et al, 1991;Fendt et al, 2018), social defeat (Kaltwasser, 1990;Tornatzky and Miczek, 1994;Kroes et al, 2007), drug withdrawal (Vivian et al, 1994;Covington and Miczek, 2003;Williams et al, 2012;Berger et al, 2013), and footshock (De Vry et al, 1993;Wöhr et al, 2005). Indeed, 22kHz USV emissions are thought to serve as alarm calls capable of warning conspecifics of possible danger and/or aversive situations (Blanchard et al, 1991;Litvin et al, 2007).…”

Sex‐dependent effects of Cacna1c haploinsufficiency on juvenile social play behavior and pro‐social 50‐kHz ultrasonic communication in rats

“…Typically, male rats are studied 51 because they express a higher frequency of social play and engage in rougher defense tactics than females. 59,60 In contrast, 50-kHz USV are believed to reflect a positive affective state ("rat laughter"), 61 as they are emitted in appetitive situations, with particularly high emission rates during and in anticipation of roughand-tumble play [62][63][64] or when social play is mimicked through an experienced human experimenter by tickling. 55 Acoustic communication is another prominent element of the rat social behavior repertoire.…”

“…They serve an alarm function and induce behavioral inhibition in the recipient rat. 59,60 In contrast, 50-kHz USV are believed to reflect a positive affective state ("rat laughter"), 61 as they are emitted in appetitive situations, with particularly high emission rates during and in anticipation of roughand-tumble play [62][63][64] or when social play is mimicked through an experienced human experimenter by tickling. [65][66][67][68] Interestingly, we recently found the emission of 50-kHz USV to be strongly affected by partial Cacna1c depletion.…”

The effects of predator odors on stress response and reproduction in Norway rats: A review

“…Thus, innate fear responses to TMT are nevertheless mediated by olfaction, not by nociception. More recently, Fendt et al (2018) showed that natural predator odor of fox urine elicited 22 kHz alarming calls in Sprague-Dawley rats. However, the researchers failed to observe such ultrasonic vocalizations in response to TMT exposure (Fendt et al, 2018).…”