Residues of nortestosterone esters at injection sites. Part 2. Behavioural effects

Anecdotal evidence in man suggests that abuse of anabolic androgenic steroids (AAS) is linked with increased aggression. In order to test the hypothesis that administration of nortestosterone (beta-NT) esters may increase aggression, behavioural effects following beta-NT phenylpropionate (NTPP) administration were assessed in male mice using the isolation-induced aggression paradigm. Mice (n = 80) were individually caged and randomly assigned to 'resident' or 'intruder' status. Residents received one of four treatments: subcutaneous (s/c) injection of oil of arachis (OILINJ), s/c injection of NTPP in oil of arachis (NTINJ), oil of arachis per os (OILOS) and NTPP in oil of arachis per os (NTOS). After treatment, weight-matched intruders were introduced into each resident's cage and the encounter was videotaped to allow the frequency (f) and duration (d) of social, non-social, offensive and defensive behaviours displayed by residents and intruders to be measured. The latency of bite attack for residents was significantly shorter in NTOS compared to OILOS. There was no difference in either f or d of aggressive behaviours between NTINJ and OILINJ. Because OILINJ residents demonstrated similar levels of aggression to NTOS, it is possible that the aggression in NTOS mice may be mediated by a different biochemical pathway. Extrapolation of these results indicate that ingestion of beta-NT esters may have a role in the induction of aggression in consumers.