Neuropharmacological aspects of adaptive pain inhibition in murine “victims” of aggression

This review outlines recent research on a subset of physiological responses in murine “victims” or aggression. In a typical resident-intruder paradigm, the detailed study of intruders has revealed that exposure to conspecific attack (and related stimuli) is associated with two forms of analgesia which appear to be integral components of the murine defensive repertoire. In response to intense/enduring attack, intruder mice display a profound, long-lasting and opioid-mediated analgesia. This reaction is highly correlated with defensive immobility and may function to reduce involuntary cues to further attack. In contrast, the inhibition of pain reactivity in mice tested immediately upon the display of defeat is less intense, shorter-lasting, non-opioid in nature and may function to facilitate active defenses such as escape. As this form of pain inhibition is also evident in intruders exposed to the scent of an aggressive male conspecific, a possible anticipatory defensive function linked to mechanisms of anxiety has been proposed. This hypothesis is supported by 1) the prevention of defeat analgesia by a range of antianxiety drugs (benzodiazepines, 5-hydroxytryptamine_1A [5-HT_1A] receptor agonists, and 5-HT₃ receptor antagonists) and 2) the effects of social defeat on behavior in the elevated plusmaze model of anxiety. These findings are discussed in relation to coping mechanisms in murine “victims” of aggression. © 1995 Wiley-Liss, Inc.     

Personality characteristics in primary benzodiazepine-dependent patients: Comparison with controls and polydrug users

The present study applied Karolinska Scales of Personality (KSP) to study (i) if patients with benzodiazepine dependence have a characteristic personality profile, (ii) if the personality characteristics in patients with benzodiazepine dependence differ from those of polydrug users and normal controls, (iii) if differences in treatment outcome existed between the groups, and (iv) if the possible difference in treatment outcome was associated with any particular personality characteristic shown by the patients. The personality characteristics of primary benzodiazepine dependent patients (BDZ) and a group of polydrug users (MIX) were studied initially (during the first week in project as an inpatient) and approximately one year after drug discontinuation, and a comparison was made with healthy controls on both test occasions. The results showed that the personality of both groups of patients differed significantly from the Controls in the following characteristics: Detachment, Socialization, Somatic Anxiety, Muscular Tension, Psychic Anxiety, and Psychasthenia. Significant differences existed between the polydrug and benzodiazepine users in Somatic and Psychic Anxiety as well as in Socialization. The MIX group differed significantly from the BDZ group and from the Controls in Suspicion. Results of treatment outcome indicated that the benzodiazepine dependent patients were significantly more successful in quitting their drug use compared to polydrug users. Further, the results demonstrated that patients scoring high in the investigated personality characteristics are those who fail the treatment goal of quitting their drug use, especially the patients with a high level of anxiety and detachment.     

Reduction of appeasement‐related affect as a concomitant of diazepam‐induced aggression: evidence for a link between aggression and the expression of self‐conscious emotions

Aggressive responding following benzodiazepine ingestion has been recorded in both experimental and client populations, however, the mechanism responsible for this outcome is unclear. The goal of this study was to identify an affective concomitant linked to diazepam‐induced aggression that might be responsible for this relationship. Thirty males (15 diazepam and 15 placebo) participated in the Taylor Aggression Paradigm while covertly being videotaped. The videotapes were analyzed using the Facial Action Coding System with the goal of identifying facial expression differences between the two groups. Relative to placebo participants, diazepam participants selected significantly higher shock settings for their opponents, consistent with past findings using this paradigm. Diazepam participants also engaged in significantly fewer appeasement expressions (associated with the self‐conscious emotions) during the task, although there were no group differences for other emotion expressions or for movements in general. Aggr. Behav. 35:203–212, 2009. © 2008 Wiley‐Liss, Inc.