This review addresses the translational relevance of animal models of stress and their effects on body weight. In humans, stress, whether chronic or acute, has often been associated with increased food intake and weight gain. In view of the current obesity epidemic, this phenomenon is especially relevant.
View Article and Find Full Text PDFIn hamsters, exposure to stress in adulthood causes increased body weight. We addressed how social stress during puberty would impact food intake and body weight. Stressed hamsters started gaining significantly more weight than controls after only two days of stress exposure.
View Article and Find Full Text PDFChronic social stress in early puberty results in enhanced impulsive action-in particular, decreased action inhibition. We address possible effects of early stress on the capacity to wait to respond, the other form of impulsive action. Male golden hamsters were exposed daily to aggressive adults from postnatal Day 28 to Day 42.
View Article and Find Full Text PDFRepeated social subjugation in early puberty lowers testosterone levels. We used hamsters to investigate the effects of social subjugation on male sexual behavior and metabolic activity within neural systems controlling social and motivational behaviors. Subjugated animals were exposed daily to aggressive adult males in early puberty for postnatal days 28 to 42, while control animals were placed in empty clean cages.
View Article and Find Full Text PDFSocial subjugation has widespread consequences affecting behavior and underlying neural systems. We hypothesized that individual differences in stress responsiveness were associated with differential expression of neurotrophin associated genes within the hippocampus and amygdala. To do this we examined the brains of hamsters placed in resident/intruder interactions, modified by the opportunity to escape from aggression.
View Article and Find Full Text PDFIn hamsters, individual differences in offensive aggression are associated with impulsive choice, leading to the characterization of a distinct impulsive-aggressive phenotype. This study had two goals: to determine the developmental trajectory of the maturation of this phenotype and to address its parental lineage. Interestingly, individuals most aggressive as adults were less likely to attack in early puberty.
View Article and Find Full Text PDFOffensive aggression in golden hamsters is inhibited by 5-hydroxytryptamine (5-HT)1A receptors and facilitated by 5-HT3 receptor activation. As such, we sought to determine whether these receptors function similarly between animals expressing an impulsive-aggressive phenotype, as compared to normal animals. Animals were screened for aggressive and impulsive choice behaviors and categorized into Low-Aggression (L-Agg) and High-Aggression (H-Agg) groups, and then tested for behavior under effective doses of 5-HT1A receptor agonist 8-hydroxy-N, N-dipropyl-2-aminotetralin (DPAT; 0.
View Article and Find Full Text PDFThis study was focused on determining the possible role of corticotropin-releasing hormone (CRH) on play fighting in juvenile golden hamsters. As no specific neural sites have been proposed, we looked for changes in CRH innervations at the peak of play-fighting activity on postnatal day 35 (P-35) from a week before on P-28. We noted that the increase in play-fighting activity between these two dates was associated with a 100% increase of the density of CRH fibers within the lateral septum.
View Article and Find Full Text PDFMany women with a history of childhood sexual abuse (CSA) experience difficulties becoming sexually aroused. This study measured cortisol and physiological sexual arousal during exposure to sexual stimuli in women with and without a history of CSA. Childhood sexual abuse survivors showed a smaller decrease in cortisol during sexual arousal than the nonsexually abused, control group potentially due to an increase in cortisol in some of the participants in the CSA group.
View Article and Find Full Text PDFIn adult male hamsters, individual differences in offensive aggression are correlated with differences in impulsive choice and decreased serotonin (5-HT) innervation. As serotonin 1A (5-HT1A) receptors participate in the inhibition of aggression, whereas 5-HT3 receptor activation facilitates aggression, the authors hypothesized that differences in their expression are associated with differences in behavior. The authors confirmed previous behavioral associations, using a delay-discounting paradigm with various delays, as high-aggression (H-Agg) hamsters preferred the immediate-reward lever over the delayed-reward lever under most delays, compared with low-aggression (L-Agg) hamsters.
View Article and Find Full Text PDFVasopressin facilitates aggression in adult hamsters. Whether this neuropeptide has a similar role in play fighting remains unknown. The goal of the present study was to identify whether vasopressin controls play fighting in juvenile golden hamsters as well.
View Article and Find Full Text PDFJuvenile hamsters are typically less vulnerable to social subjugation than adults, although they will avoid aggressive individuals in some situations. The purpose of this study was to determine the extent to which social subjugation stimulates fear- or anxiety-like behavior in juvenile hamsters in both social and non-social contexts. Social context testing was conducted in a Y-maze while the non-social context apparatus consisted of an open field arena and a lat-maze.
View Article and Find Full Text PDFPeer victimization in the form of bullying is a chronic social stressor experienced by many humans during development. Exposure to bullying has been associated with a variety of mental disorders, such as anxiety and depression. Participants pre-selected for the presence or absence of a history of being bullied were brought into a laboratory and placed in a stressful situation.
View Article and Find Full Text PDFIn hamsters, play fighting matures gradually into adult aggression. As these two behaviors share many similarities in this species, we predicted that a single neural circuitry controls their offensive component. The goal of the present study was to identify neural systems associated with offensive play fighting in male juvenile golden hamsters.
View Article and Find Full Text PDFIn humans, reactive aggression is associated with impulsivity. The purpose of this study is to relate reactive and impulsive aggression in humans with offensive aggression in animals and identify neurobiological correlates associated with certain forms of the behavior. We predicted that individual differences in offensive aggression are associated with individual differences in impulsivity.
View Article and Find Full Text PDFDuring 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.
View Article and Find Full Text PDFAfter an initial increase, repeated exposure to a particular stimulus or familiarity with an event results in lower immediate early gene expression levels in relevant brain structures. We predicted that similar effects would occur in Japanese quail after repeated sexual experience within brain areas involved in sexual behavior, namely, the medial preoptic nucleus (POM), the bed nucleus of stria terminalis (BST), and the nucleus taeniae of the amygdala (TnA), an avian homolog of medial amygdala. High experience subjects copulated with a female once on each of 16 consecutive days, whereas low experience subjects were allowed to copulate either once or twice.
View Article and Find Full Text PDFIn male golden hamsters, agonistic behavior undergoes a pubertal transition from play fighting to adult aggression. Previous studies have shown that this aspect of behavioral development is associated with pubertal increases in glucocorticoids and that daily social stress or injections of a synthetic glucocorticoid accelerate the transition. The goals of this study were to confirm the effects of cortisol on the development of agonistic behavior and to investigate the role of type II corticosteroid receptors in this process.
View Article and Find Full Text PDFIn hamsters, the maturation of aggression during puberty is associated with a gradual reduction of offensive responses. The purpose of this study was to analyze the changes during this decrease to provide an enhanced description of the behavior. During early puberty, play-fighting is characterized by long and continuous contact duration throughout the encounter and repetitive attacks within bouts of agonistic interaction.
View Article and Find Full Text PDFIn male golden hamsters (Mesocricetus auratus), attack frequency decreases during puberty. As serotonin inhibits offensive responses in adult hamsters, it is hypothesized that the serotonin system becomes upregulated in the hypothalamus during puberty. This hypothesis was tested through acute treatment with fluoxetine, a serotonin reuptake inhibitor, as well as through analysis of serotonin innervation in specific brain areas.
View Article and Find Full Text PDFPrevious research has shown orexin/hypocretin immunoreactive (orexin-ir) neurons in domesticated Galliformes. However, these findings may not be representative of other birds and these studies did not include a distribution of orexin-ir projections throughout the brain. The present study was carried out in a wild-caught passerine, the house finch, Carpodacus mexicanus, and includes a detailed description of orexin-ir neurons and their projections.
View Article and Find Full Text PDF