Wistar–Kyoto rats as an animal model of anxiety vulnerability: Support for a hypervigilance hypothesis

Abstract

Inbred Wistar-Kyoto (WKY) rats have been proposed as a model of anxiety vulnerability as they display behavioral inhibition and a constellation of learning and reactivity abnormalities relative to outbred Sprague-Dawley (SD) rats. Together, the behaviors of the WKY rat suggest a hypervigilant state may contribute to its anxiety vulnerability. To test this hypothesis, open-field behavior, acoustic startle, pre-pulse inhibition and timing behavior were assessed in WKY and Sprague Dawley (SD) rats. Timing behavior was evaluated using a modified version of the peak-interval timing procedure. Training and testing of timing first occurred without audio-visual (AV) interference. Following this initial test, AV interference was included on some trials. Overall, WKY rats took much longer to leave the center of the arena, made fewer line crossings, and reared less, than did SD rats. WKY rats showed much greater startle responses to acoustic stimuli and significantly greater pre-pulse inhibition than did the SD rats. During timing conditions without AV interference, timing accuracy for both strains were similar; peak times for WKY and SD rats were not different. During interference conditions, however, the timing behavior of the two strains was very different. Whereas peak times for SD rats were similar between non-interference and interference conditions, peak times for WKY rats were shorter and response rates higher in interference conditions than in non-interference conditions. The enhanced acoustic startle response, greater prepulse inhibition and altered timing behavior with audio-visual interference supports a characterization of WKY strain as hypervigilant and provides further evidence for the use of the WKY strain as a model of anxiety vulnerability.

Genotype-dependent responsivity to inflammatory pain: A role for TRPV1 in the periaqueductal grey

“…This result contrasts with previous studies in our laboratory Olango, 2012) and others (Braw et al, 2006;Malkesman et al, 2005;McAuley et al, 2009;Smith et al, 2016), which demonstrated that WKY rats spend significantly less time in the inner zone compared with SD rats. However, in the present study, the WKY rats spent most of the time freezing in the inner zone of the open field when compared to the SD rats.…”

“…The fact that WKY rats exhibited lower locomotor activity but yet higher formalin-evoked nociceptive behaviour compared with SD rats suggests that their hyperalgesic behaviour is expressed independently of, and despite, their hypo locomotor activity and likely reflects exacerbated nociception in this inbred strain. Taken together, the results presented herein confirm that WKY rats display greater anxiety-and pain-related behaviour in line with the previous studies from our lab and others (Braw et al, 2006;Gentsch et al, 1987;Hyland et al, 2015;McAuley et al, 2009;Rea et al, 2014;Smith et al, 2016).…”

“…freezing) nature of WKY rats when exposed to a novel environment such as the open field Olango, 2012). This is reflected in the data for total distance moved throughout the entire open field which was significantly lower in WKY rats compared with SD counterparts, in agreement with previous studies from our laboratory Olango, 2012) and others (Braw et al, 2006;Malkesman et al, 2005;McAuley et al, 2009;Smith et al, 2016). WKY rats exhibited anxiety-like behaviour in the EPM test i.e.…”

Animal Models of Anxiety Vulnerability - The Wistar Kyoto Rat

“…The ASR can be used to reveal differences in sensitivity (threshold to elicit a reflex response), responsivity (the magnitude of response), latency, as well as nonassociative processes of habituation, dishabituation and sensitization. We and others demonstrated that WKY rats made larger startle responses to a white noise within a wide range (92dB to 120dB) as compared to other inbred and outbred rat strains (Glowa and Hansen, 1994;McAuley et al, 2009;Servatius et al, 1998). Of 45 inbred and outbred rat strains including SD rats, male WKY rats exhibited the highest ASR magnitude when exposed to 8 trials of 110dB white noise (Glowa and Hansen, 1994).…”

“…Unlike its parent strain WIS rat, the WKY rat exhibits many unique behavioral characteristics differing from an out-bred rat strain. The most significant features are behavioral withdrawal, propensity to avoid, hyper-responsiveness to stress and hypervigilance (Drolet et al, 2002;Lemos et al, 2011;McAuley et al, 2009;Pare, 1992a;Pare, 1989b;Pare, 1992b;Pare, 1993;Solberg et al, 2001). …”