Discrimination of anxiety- versus panic-like behavior in the wall lizard Tropidurus oreadicus.

Abstract

A behavioral test battery is proposed for wall lizards (Tropidurus oreadicus) that consists of inducing tonic immobility (TI) followed by post-TI behavioral scoring. After the induction of TI, the usual behavioral sequence was flight followed by freezing and tongue-flicking and/or thigmotaxis, with flight being more probable than freezing. These sequences were not observed after restraint in a normal upward position (which induced freezing but not TI) or after handling (which increased the probability of tongue-flicking). Alprazolam and imipramine selectively decreased the duration of TI as well as the following flight and freezing behavior. Tongue-flicking was increased by diazepam and alprazolam, whereas fluoxetine decreased it. Finally, thigmotaxis was reduced by diazepam, alprazolam, and imipramine but increased by fluoxetine. These results suggest that panic and anxiety can be discriminated pharmacologically in wall lizards.

FGIN-1-27, an agonist at translocator protein 18 kDa (TSPO), produces anti-anxiety and anti-panic effects in non-mammalian models

“…In the lizard defense test battery, induction of TI produces a stereotypical behavioral pattern in which is followed by either freezing or "explosive" circling behavior; after that, the animal emits exploratory behavior, marked by thigmotaxis ("wall-hugging") and tongue-flicking (Maximino et al, 2014). This sequence resembles defensive behavior at increasing predatory imminence continua (Fanselow and Lester, 1988) -that is, defensive behavior in this test shifts from panic-like, circastrike behavior towards sustained risk assessment (i.e., tongue-flicking, thigmotaxis).…”

“…For both diazepam and FGIN-1-27, the doses used were 0.14, 0.28, 0.57, 1.1, and 2.3 mg/kg . The three highest doses were chosen based on reported effects of diazepam on zebrafish (Maximino et al 2010) or wall lizard (Maximino et al 2014) defensive behavior, and were identical for both drugs to facilitate comparison; the lower doses were chosen in order to define a minimal effect. All drugs were acquired from Tocris Bioscience (UK).…”

“…Adult lizards were asigned to 12 independent groups (n= 10 lizards per group): a vehicle group the doses described above for diazepam (5 groups) or FGIN-1-27 (5 groups). Sample sizes were based on Maximino et al (2014). All drugs were i.p.…”

“…The defense test battery was applied as described by Maximino et al (2014). Briefly, tonic immobility was induced by carefully placing the animal on its back in the center of a 10 cm diameter circular open field and applying mild pressure to the thorax and pelvis while restraining the limbs.…”

“…In zebrafish, for example, benzodiazepines have been shown to affect a plethora of anxiety-like behaviors, from bottom-dwelling (Bencan et al, 2009;Egan et al, 2009) and dark preference (Maximino et al, 2010(Maximino et al, , 2011 to shoal cohesion (Gebauer et al, 2011) and cocaine withdrawal-induced anxiety (López-Patiño et al, 2008). Likewise, benzodiazepines decrease tonic immobility duration and the following freezing and explosive behavior in a defensive behavior battery in the wall lizard (Tropidurus oreadicus), and also increase exploratory behavior in the same test (Maximino et al, 2014). In the separation stress paradigm, benzodiazepines attenuate separation stress-induced distress vocalizations in chicks in the anxiety phase, but not in the depression phase (Warnick et al, 2009).…”