Stress, Aggression, and Puberty: Neuroendocrine Correlates of the Development of Agonistic Behavior in Golden Hamsters

Abstract

During puberty, agonistic behaviors undergo significant transitions. In golden hamsters, puberty is marked by a transition from play fighting to adult aggression. During early puberty, male golden hamsters perform play-fighting attacks. This response type is gradually replaced by adult attacks over the course of puberty. Interestingly, this behavioral transition does not appear to be controlled by changes in gonadal steroids. Instead, the shift from play fighting to adult aggression in male golden hamsters is driven by pubertal changes in glucocorticoid levels. Specifically, the transition from play fighting to adult aggression coincides with developmental increases in glucocorticoid levels, and external manipulations such as social stress or treatment with corticosteroid receptor agonists accelerate this behavioral shift. Moreover, the consequences of social stress differ greatly between juvenile and adult male golden hamsters. Although a single defeat during adulthood causes severe and long lasting behavioral and neuroendocrine consequences, socially subjugated juveniles show only transient behavioral effects. As such, it is likely that pubertal changes in the HPA axis are not only linked to the maturation of offensive responses but also determine the consequences of social stress. Combined, these studies in golden hamsters provide a novel mechanism for the development of agonistic behavior and suggest that age related differences in behavioral plasticity are mediated by the development of the HPA axis.

Contrasting hippocampal and amygdalar expression of genes related to neural plasticity during escape from social aggression

“…Test animals were 42 days old and approximately 100 g when experiments began. Postnatal day 42 is a critical point in the development of the hamster where social behaviors and stress responsiveness start to resemble that of an adult [49]. All 10 residents used were retired breeders older than 12 weeks, previously tested and used for aggression, and weighed approximately 140 g. All animal experiments were executed in a manner that minimized suffering and the number of animals used, in accordance with National Institutes of Health Guide for the Care and Use of Laboratory Animals (NIH Publications No.…”

Neurochemical correlates of accumbal dopamine D2 and amygdaloid 5-HT1B receptor densities on observational learning of aggression

“…In contrast, note that chronic stress is not associated with a compensatory downregulation of D2R density in the AcbSh immediately after stress (Lucas, Wang, McCall, & McEwen, 2007) or even after a recovery period (Lucas et al, 2004; Yohe et al, 2012). Accordingly, our findings were less likely to be confounded with any social stress effect (Tzanoulinou, Riccio, de Boer, & Sandi, 2014; Wommack & Delville, 2007), as no group difference was observed in the levels of serum corticosterone immediately following passive exposure (see Table 1). …”

Syrian hamster males below an age threshold do not elicit aggression from unfamiliar adult males

“…However, in yet another study in which two hamster males were paired at either 28 days of age or 65 days of age, younger males (28 d) were more aggressive than older males (65 d) [Romeo et al, 2003]. The pattern of aggression in hamsters and the areas of the body that are targeted during an attack change throughout male development, but some form of aggression (including play fights) is present at all ages starting at 15-20 days of age [Delville et al, 2005;Wommack and Delville, 2007]. It is possible, however, that in the presence of an adult male, young males under 48-50 days of age display submissive behaviors that do not elicit aggression from the adult males.…”