Effects of the benzodiazepine inverse agonist FG7142 on the structure of anxiety-related behavior of male Wistar rats tested in hole board

Abstract

Present study provides a useful tool to analyze behavioral responses to different anxiety conditions. Accordingly, it is demonstrated that a condition of increased anxiety deeply modifies the structure of male Wistar rat's behavior in hole board. In addition, our results suggest that evaluation of head dip/edge sniff ratio can be considered a reliable index to appraise effects of pharmacological manipulation of anxiety and related behavioral elements.

Multivariate approaches to behavioral physiology

“…It goes without saying that simple quantitative measures of head-dip alone should be avoided or, at least, very prudently used. Consistently, we showed that when head-dip is evaluated in terms of its relationships with another component of the rodent's repertoire, namely the sniffing of the edges of the holes (edge-sniff), the effects of anxiolytics and anxiety-inducing molecules become behaviorally coherent [3, 4]. The explanation of such an outcome probably lies in the emotional/motivational load underlying the relationship between the sniffing of the hole-edges and the insertion of the head inside the holes [3, 4].…”

“…Consistently, we showed that when head-dip is evaluated in terms of its relationships with another component of the rodent's repertoire, namely the sniffing of the edges of the holes (edge-sniff), the effects of anxiolytics and anxiety-inducing molecules become behaviorally coherent [3, 4]. The explanation of such an outcome probably lies in the emotional/motivational load underlying the relationship between the sniffing of the hole-edges and the insertion of the head inside the holes [3, 4]. In brief, we hypothesized that the transition from edge-sniff to head-dip has not the same weight of the opposite transition, from head-dip to edge-sniff: the former transition, indeed, representing the shift from the exploration of the border to the insertion of the head inside, would be heavily dependent on animal's motivation to explore and, as such, heavily influenced by anxiety level and related pharmacological manipulations [3, 4]; on the contrary, the latter transition (from head-dip to edge-sniff), representing the conclusion of the hole-exploration process would be, presumably, much less influenced by anxiety level.…”

“…Such a lack of consensus, well underlined by Brown and Nemes [2], emerges also from our researches. For instance, on the one hand we have not observed significant changes of head-dip frequencies following anxiolytic treatment [3], on the other hand, the administration of a potent anxiety-inducing molecule provoked evident increases of head-dip count [4]. It goes without saying that simple quantitative measures of head-dip alone should be avoided or, at least, very prudently used.…”

“…The explanation of such an outcome probably lies in the emotional/motivational load underlying the relationship between the sniffing of the hole-edges and the insertion of the head inside the holes [3, 4]. In brief, we hypothesized that the transition from edge-sniff to head-dip has not the same weight of the opposite transition, from head-dip to edge-sniff: the former transition, indeed, representing the shift from the exploration of the border to the insertion of the head inside, would be heavily dependent on animal's motivation to explore and, as such, heavily influenced by anxiety level and related pharmacological manipulations [3, 4]; on the contrary, the latter transition (from head-dip to edge-sniff), representing the conclusion of the hole-exploration process would be, presumably, much less influenced by anxiety level. This example, concerning the analysis of the existing patterning between head-dip and edge-sniff calls a stimulating topic of discussion.…”

“…These analytical tools belong to the realm of multivariate analyses. Examples are represented by hierarchical clustering [4], stochastic analysis [5], adjusted residuals [6], T-pattern analysis [7, 8]. Figure 1 presents a synopsis concerning the application of various multivariate approaches to the study of behavior.…”