PubMed · 14724024
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Norman M Kaplan. 2004-01-03. Inappropriate aggression.. https://doi.org/10.1016/s0140-6736(03)15216-6
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We used a phytoestrogen (PE) and a phytoestrogen-free (PE-Free) diet to determine whether or not diet can have neurobehavioral effects on intermale aggression in Syrian hamsters (Mesocricetus auratus). In Experiment 1, 20 adult male hamsters were pre-tested for aggression and then placed on a PE (n=10) or a PE-Free diet (n=10) for 4 weeks in isolation. During week 5, experimental hamsters were exposed to a group-housed, nonaggressive opponent (NAO) for 5 min in a neutral cage arena. PE-fed hamsters exhibited more attacks (33.4+/-6.1) toward the NAO compared to the PE-Free-fed hamsters (18.1+/-4) (p<0.05). Interestingly, testosterone in the blood serum was higher in the PE-fed group (11.01+/-1.48 ng/ml) compared to the PE-Free group (6.5+/-0.87 ng/ml). In Experiment 2, 16 juvenile hamsters were weaned onto a PE (n=8) or a PE-Free diet (n=8). After 7 weeks on the diet, experimental hamsters were exposed to a NAO for 5 min in a neutral cage arena. Although the PE group exhibited higher levels of aggressive behavior, there were no statistically significant differences between groups. However, the PE group had higher levels of testosterone (9.0+/-0.95 ng/ml) compared to the PE-Free group (4.6+/-0.98 ng/ml) (p<0.05). In addition, analysis of the brains from both experiments revealed differences in binding for vasopressin 1A (V1A) receptors. Optical densities were converted to disintegrating units per min/mg. The PE-Free group had higher levels of V1A receptor binding (2689.93+/-254.8 dpm/mg) compared to the PE group (1907.32+/-136.3 dpm/mg) in the lateral septum (p<0.05). In addition, there were differences in the lateral hypothalamus, but the PE group had higher receptor binding (2550.9+/-63.59 dpm/mg) when compared to the PE-Free group (2011.9+/-174.14 dpm/mg) (p<0.05). In sum, these data present the first evidence that phytoestrogens can affect aggressive behavior and, concurrently, alter hormonal status and stimulate changes in the brain of male hamsters.
Bullying victimization is associated with several health issues. Prevention of bullying is therefore an important goal for health and education professionals. In the present study, 2766 children from 32 Dutch elementary schools participated by completing a questionnaire on bullying behavior, and the involvement of teachers, parents and classmates in bullying incidents. The results of this study show that bullying is still prevalent in Dutch schools. More than 16% of the children aged 9-11 years reported being bullied on a regular basis and 5.5% reported regular active bullying during the current school term. Almost half of the bullied children did not tell their teacher that they were being bullied. When teachers knew about the bullying, they often tried to stop it, but in many cases the bullying stayed the same or even got worse. With regard to active bullying, neither the majority of the teachers nor parents talked to the bullies about their behavior. Our results stress the importance of regular communication between children, parents, teachers and health care professionals with regard to bullying incidents. In addition, teachers need to learn effective ways to deal with bullying incidents. Schools need to adopt a whole-school approach with their anti-bullying interventions.
To clarify the social functions of play panting in chimpanzees, I investigated when they emitted play panting in social play and how the interactions were affected by the occurrence of play panting. The subjects were the M-group chimpanzees living in Mahale, Tanzania. The following observations were made: (1) chimpanzees emitted play panting when they were tickled or chased but rarely did so when they tickled or chased others. Chimpanzee play panting does not have the function of a play signal communicating that these "aggressive" actions are performed not as aggression but as play. (2) Chimpanzees emitted play panting more often when they received "aggressive" actions that supposedly elicited higher arousal. (3) A chimpanzee tended to continue to perform "aggressive" actions when the target emitted play panting. Play panting activates the interaction of social play by encouraging the performer to continue tickling or chasing. These results can be summarized as showing that chimpanzee play panting serves as positive feedback to the play partner for continuing somewhat fragile interactions, which may contain the risk of excessive arousal and the risk of confusing "defensive" actions by the target of the "aggressive" actions with real efforts to escape the situation.