Alterations in anterior hypothalamic vasopressin, but not serotonin, correlate with the temporal onset of aggressive behavior during adolescent anabolic-androgenic steroid exposure in hamsters (Mesocricetus auratus).

In hamsters (Mesocricetus auratus), anabolic-androgenic steroid (AAS) exposure during adolescence facilitates offensive aggression that is correlated with the enhanced development of the arginine vasopressin (AVP) neural system and reduced development of the serotonin (5-HT) neural system in the anterior hypothalamus (AH). This study examined the temporal onset of these effects by measuring aggression and AH AVP and 5-HT during progressively shorter periods of AAS exposure during adolescent development. The authors tested adolescent hamsters that received AAS for 3, 7, 14, or 28 days for offensive aggression and then examined the hamsters for AVP/5-HT afferent innervation to the AH using immunohistochemistry. While reductions in AH 5-HT afferent innervation were detectable by 7 days of AAS exposure, no concomitant increases in offensive aggression were observed compared to oil-treated littermates. In contrast, by Day 14 of AAS treatment, AH AVP and offensive aggression were significantly higher than oil-treated controls. These data indicate that relatively short-term adolescent AAS exposure alters aggression and AH 5-HT and AVP development, yet only alterations in AH AVP development correlate with temporal onset of the aggressive behavioral phenotype during adolescent AAS exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plasticity in anterior hypothalamic vasopressin correlates with aggression during anabolic-androgenic steroid withdrawal in hamsters.

In hamsters, adolescent anabolic-androgenic steroid (AAS) exposure facilitates offensive aggression, in part by altering the development and activity of anterior hypothalamic arginine vasopressin (AH-AVP). This study assessed whether these effects were lasting by examining aggression and AH-AVP during AAS withdrawal. Adolescent hamsters administered AAS were tested as adults for aggression at 1, 4, 11, 18, or 25 days of withdrawal, sacrificed the following day, and examined for AH-AVP afferent innervation using immunohistochemistry. Through Day 12 of withdrawal, aggression and AVP were significantly higher in AAS-treated hamsters than in controls. These differences were no longer observable by Day 19 of withdrawal, at which point the behavior and neurobiology of AAS-treated hamsters reverted to that observed in controls. These data indicate that adolescent AAS exposure has short-term, reversible effects on both aggression and AH-AVP, correlating AH-AVP with the aggressive/nonaggressive behavioral phenotype during AAS withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serotonin-1B receptor activity and expression modulate the aggression-stimulating effects of adolescent anabolic steroid exposure in hamsters.

Repeated high dose (5.0 mg/kg) anabolic-androgenic steroid (AAS) exposure during adolescence stimulates offensive aggression in male Syrian hamsters. These studies examined whether AAS-induced aggression was regulated by the activity of serotonin (5HT) type-1B receptors and correlated with altered 5HT1B expression. AAS-treated hamsters were tested for offensive aggression following the administration of the 5HT1B agonist anpirtoline (0.125-0.5 mg/kg). Anpirtoline dose-dependently reduced select components of the AAS-induced aggressive response, with significant reductions observed at 0.25 mg/kg. Aggressive, AAS-treated hamsters showed significant decreases in the area covered by 5HT1B-containing neuronal puncta and increases in the number of 5HT1B-containing neuronal somata in select brain regions implicated in aggression control. Together, these data support a role for site-specific alterations in 5HT1B signaling and expression in adolescent AAS-induced aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How golden hamsters (Mesocricetus auratus) discriminate top from bottom flank scents in over-marks.

Using a habituation-discrimination paradigm, the authors investigated what cues male golden hamsters (Mesocricetus auratus) use to determine the top and bottom positions in flank gland over-marks. A difference in the ages of 2 hamsters' marks did not, by itself, produce differential memory or evaluation of the 2 scents. A spatial configuration of marks suggestive of an overlap was sufficient for the apparently overlapping scent to be remembered or valued more than the apparently underlying scent. Cues from the overlap of 2 hamsters' marks were also sufficient. These results, consistent with those previously found for responses to hamster vaginal scent over-marks, suggest that hamsters use similar cues to analyze scent over-marks that are different in chemical composition and in social functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential responses to serotonin receptor ligands in an impulsive-aggressive phenotype.

Offensive 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; 0.1 mg/kg and 0.3 mg/kg) or 5-HT3 receptor antagonist tropisetron (0.3 mg/kg) treatment. Low-dose DPAT treatment inhibited both behaviors in H-Agg animals, however yielding more modest effects in L-Agg animals; while high-dose DPAT effects were confounded by side effects on locomotion. Tropisetron, on the other hand, had differential effects between groups, as aggression and impulsive choice were both inhibited in H-Agg animals, while enhanced in L-Agg individuals. In addition, while the effects of the 5-HT1A receptor were limited, the broad effects of 5-HT3 receptor included repetitive and impulsive elements of behavior, pointing to the importance of the receptor's role in the modulation of these particular aspects within the phenotype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aggression Upon Adolescent Cocaine Exposure Linked to Serotonin Anomalies: Theoretical Comment on Ricci et al. (2004).

Aggressive tendencies may be linked to the psychopharmacology of cocaine, yet few experimental approaches have been brought to bear on understanding the neurobiological implications of cocaine exposure during the developmentally sensitive period of adolescence. In this issue, Melloni and coauthors (L. A. Ricci, J. M. Grimes, & R. H. Melloni, 2004; see record 2004-19432-025) present convincing evidence that the development of serotonin signal cascades in key brain regions can be disrupted by cocaine administration, resulting in an aggressive response in adolescents. These findings may allow the development of new therapeutic approaches to tailor pharmacotherapy for adolescents experiencing problems with aggressive behavior and/or impulse control associated with illicit drug use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estradiol induces hypothalamic progesterone receptors but does not activate mating behavior in male hamsters (Mesocricetus auratus) before puberty.

This study investigated pubertal changes in neural and behavioral responses to estradiol. Gonadectomized pre- and postpubertal male hamsters (Mesochcetus auratus) were treated with 0.00, 0.05, 0. 10, or 0.2 mg estradiol and tested 1 week later for sexual behavior with a receptive female. Estradiol activated behavior in postpubertal, but not prepubertal, males. In contrast, estrogen receptor α (ERα) and progesterone receptor (PR) immunoreactivity in forebrain nuclei that mediate mating behavior was similar in pre- and postpubertal males. Thus, absence of a behavioral response before puberty is not associated with reduced levels of steroid receptors. Because estradiol induced PR in prepubertal males these data also suggest that ERα is functional before puberty. Therefore, gonadal steroids facilitate male reproductive behavior only after as-yet-unidentified developmental processes occur during puberty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serotonin impairs copulation and attenuates ejaculation-induced glutamate activity in the medial preoptic area.

The medial preoptic area (MPOA) is critical for male sexual behavior. Glutamate is released in the MPOA of male rats during copulation, and increasing glutamate levels by reverse dialysis of glutamate uptake inhibitors facilitates mating. Conversely, increased release of serotonin (5-HT) inhibits sexual behavior. In both rats and men, selective serotonin reuptake inhibitors (SSRIs) impair erection, ejaculation, and libido. Here we reverse-dialyzed 5-HT through concentric microdialysis probes in the MPOA of male rats; concurrently we collected 2-min samples for analysis of glutamate and measured sexual behavior. Sexual activity, and especially ejaculation, increased levels of glutamate in the MPOA. However, reverse dialysis of 5-HT into the MPOA impaired ejaculatory ability and attenuated glutamate release. Implications of these results for impairment of sexual behavior that results from administration of SSRIs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Play, aggression, the preschool child, and the family: A review of literature to guide empirically informed play therapy with aggressive preschool children.

Preschool-aged children displaying high levels of aggression repeatedly have been shown to be at significant risk for continued behavior problems and other social and emotional challenges throughout their lifetimes. The present literature review seeks to summarize and integrate findings across the fields of developmental psychology, family studies, child development, and play therapy to inform play therapists' practices with this population. Specifically, findings from research in these fields hold substantial implications for empirically informed ways in which play therapists can include parents within play therapy processes. Affective quality of parent- child interactions emerges as the common theme across all existing literature and is emphasized as a critical focus for play-based therapeutic intervention. Topics for future research by play therapists focusing on this population are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Morningness/eveningness, morning-to-afternoon cortisol ratio, and antisocial behavior problems during puberty.

The relationship between morningness/eveningness (M/E) and morning-to-afternoon cortisol ratio, pubertal timing, and antisocial behavior was examined in 111 girls and boys ages 8 to 13 years. Cortisol levels showed a significant increase after awakening and declined thereafter ( p     

Taste response to mixtures: Analytic processing of quality.

The tastes of 100 mM sodium chloride (NaCl), 100 mM sucrose, and 1 mM quinine hydrochloride in mixtures were investigated in golden hamsters (Mesocricetus auratus) with a conditioned taste aversion (CTA) paradigm. CTAs, established in golden hamsters by injection of lithium chloride, were quantified as percent suppression of control 1-hr stimulus intake. CTAs for 10 of 15 stimulus pairs with common components symmetrically cross-generalized, suggesting that component qualities were recognized in binary and ternary mixtures. However, CTAs to quinine were hardly learned and were weakly expressed when quinine was mixed with NaCl, and generalizations from multiple to single stimuli were stronger than vice versa (i.e., asymmetric). The behaviors reflect peripheral inhibition and/or central mixture suppression. Nonetheless, components retain their distinct qualities in mixtures, suggesting that taste processing is analytic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serotonergic function, two-mode models of self-regulation, and vulnerability to depression: What depression has in common with impulsive aggression.

Evidence from diverse literatures supports the viewpoint that two modes of self-regulation exist, a lower-order system that responds quickly to associative cues of the moment and a higher-order system that responds more reflectively and planfully; that low serotonergic function is linked to relative dominance of the lower-order system; that how dominance of the lower-order system is manifested depends on additional variables; and that low serotonergic function therefore can promote behavioral patterns as divergent as impulsive aggression and lethargic depression. Literatures reviewed include work on two-mode models; studies of brain function supporting the biological plausibility of the two-mode view and the involvement of serotonergic pathways in functions pertaining to it; and studies relating low serotonergic function to impulsiveness, aggression (including extreme violence), aspects of personality, and depression vulnerability. Substantial differences between depression and other phenomena reviewed are interpreted by proposing that depression reflects both low serotonergic function and low reward sensitivity. The article closes with brief consideration of the idea that low serotonergic function relates to even more diverse phenomena, whose natures depend in part on sensitivities of other systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rumination as a vulnerability factor to depression during the transition from early to middle adolescence: A multiwave longitudinal study.

The current study examined vulnerability to depression during the transition from early to middle adolescence from the perspective of the response styles theory. During an initial assessment, 382 adolescents (ages 11–15 years) completed self-report measures assessing rumination and depressive symptoms as well as a semistructured clinical interview assessing current and past major depressive episodes. Every 3 months for the subsequent 2 years, adolescents completed self-report measures assessing depressive symptoms and negative events. Every 6 months, adolescents completed a semistructured clinical interview assessing the onset of new major depressive episodes. Higher levels of rumination were associated with a greater likelihood of exhibiting a past history of major depressive episodes, a greater likelihood of experiencing the onset of a future major depressive episode, and greater duration of future depressive episodes. Consistent with a vulnerability-stress perspective, rumination moderated the association between the occurrence of negative events and the development of future depressive symptoms and major depressive episodes. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Defensive behavior and hippocampal cell proliferation: Differential modulation by naltrexone during stress.

The present study investigated the role of endogenous opioids in the expression of defensive behaviors (DBs) and the suppression of cell proliferation (CP) in the dentate gyrus (DG) induced by exposure to predator odor, trimethyl thiazoline (TMT). Adult male rats were injected with either naltrexone (an opioid antagonist, 5 mg/kg) or saline 30 min before exposure to either TMT or a control odor. Behavior was scored for the first 15 min of odor exposure. Bromodeoxyuridine (BrdU, 200 mg/kg) was then injected, and the rats were perfused 1 hr later. Exposure to TMT increased the expression of DBs and suppressed the number of proliferating cells in the DG. Pretreatment with naltrexone attenuated the effects of TMT on DB expression but did not attenuate the effects of TMT on CP. In addition, naltrexone administration suppressed CP in the absence of TMT. These results demonstrate a dissociation between DBs and regulation of CP in the DG. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Involvement of Central Amygdalar and Bed Nucleus of the Stria Terminalis Corticotropin-Releasing Factor in Behavioral Responses to Social Defeat.

The authors investigated whether corticotropin-releasing factor (CRF) within the central nucleus of the amygdala (CeA) and bed nucleus of the stria terminalis (BNST) is a critical component of the neural circuitry mediating conditioned defeat. In this model, hamsters that have experienced social defeat subsequently display only submissive-defensive agonistic behavior instead of territorial aggression. Conditioned defeat was significantly reduced following infusion of the CRF receptor antagonist D-Phe CRF(12-41) into the BNST but not into the CeA. In another experiment, hamsters given unilateral lesions of the CeA and infusions of D-Phe CRF(12-41) into the contralateral BNST displayed significantly less submissive behavior than did controls. These data suggest that CRF acts within a neural circuit that includes the amygdala and the BNST to modulate agonistic behavior following social defeat. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coping with perceived peer stress: Gender-specific and common pathways to symptoms of psychopathology.

This study investigated gender differences in the moderating and mediating effects of responses to stress on the association between perceived peer stress and symptoms of psychopathology. A sample of 295 middle school students (63.7% female; Mage = 12.39 years, SD = 0.99) completed self-report surveys on stress, coping, and behavioral problems. Involuntary responses to stress (e.g., physiological arousal, intrusive thoughts, impulsive action) mediated the association between perceived stress and anxiety/depression and aggression for girls and for boys. Disengagement coping (e.g., denial, avoidance) partially mediated the association between peer stress and anxiety/depression for boys and for girls. In contrast, disengagement coping mediated the association between peer stress and overt aggression for boys only. Finally, engagement coping (e.g., problem solving, emotion regulation, cognitive restructuring) buffered the indirect effect of peer stress on symptoms of psychopathology for girls only. Implications for prevention and intervention efforts are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The generalization of attachment representations to new social situations: Predicting behavior during initial interactions with strangers.

The idea that attachment representations are generalized to new social situations and guide behavior with unfamiliar others is central to attachment theory. However, research regarding this important theoretical postulate has been lacking in adolescence and adulthood, as most research has focused on establishing the influence of attachment representations on close relationship dynamics. Thus, the goal of this investigation was to examine the extent to which attachment representations are predictive of adolescents' initial behavior when meeting and interacting with new peers. High school adolescents (N = 135) participated with unfamiliar peers from another school in 2 social support interactions that were videotaped and coded by independent observers. Results indicated that attachment representations (assessed through interview and self-report measures) were predictive of behaviors exhibited during the discussions. Theoretical implications of the results and contributions to the existing literature are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affiliation with antisocial peers, susceptibility to peer influence, and antisocial behavior during the transition to adulthood.

Developmental theories suggest that affiliation with deviant peers and susceptibility to peer influence are important contributors to adolescent delinquency, but it is unclear how these variables impact antisocial behavior during the transition to adulthood, a period when most delinquent individuals decline in antisocial behavior. Using data from a longitudinal study of 1,354 antisocial youth, the present study examined how individual variation in exposure to deviant peers and resistance to peer influence affect antisocial behavior from middle adolescence into young adulthood (ages 14 to 22 years). Whereas we find evidence that antisocial individuals choose to affiliate with deviant peers, and that affiliating with deviant peers is associated with an individual’s own delinquency, these complementary processes of selection and socialization operate in different developmental periods. In middle adolescence, both selection and socialization serve to make peers similar in antisocial behavior, but from ages 16 to 20 years, only socialization appears to be important. After age 20, the impact of peers on antisocial behavior disappears as individuals become increasingly resistant to peer influence, suggesting that the process of desistance from antisocial behavior may be tied to normative changes in peer relations that occur as individuals mature socially and emotionally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Growth in temperament and parenting as predictors of adjustment during children's transition to adolescence.

The author examined relations among demographic risk (income, maternal education, single-parent status), growth in temperament (fear, irritability, effortful control), and parenting (rejection, inconsistent discipline) across 3 years and the prediction of children's adjustment problems in a community sample (N=190; ages 8-12 years at Time 1). Family income was related to higher initial levels of fear, irritability, rejection, and inconsistency and lower effortful control but was not related to changes in these variables. Higher initial rejection predicted increases in child fear and irritability. Higher initial fear predicted decreases in rejection and inconsistency. Higher initial irritability predicted increases in inconsistency, and higher initial effortful control predicted decreases in rejection. When growth of parenting and temperament were considered simultaneously, increases in effortful control and decreases in fear and irritability predicted lower Time 3 internalizing and externalizing problems. Increases in rejection and inconsistent discipline predicted higher Time 3 externalizing, although sometimes the effect appeared to be indirect through temperament. The findings suggest that temperament and parenting predict changes in each other and predict adjustment during the transition to adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aggressiveness, family history of alcoholism, and the heart rate response to alcohol intoxication.

Some sons of male alcoholics (SOMAS) are characterized by an increased heart rate (HR) response to alcohol intoxication, which is thought to reflect increased sensitivity to alcohol-induced reward. Such a response has also been related to increased physical aggression. However, the confounding effect of aggression in SOMAS may be obscuring the interpretation of these findings. The HR response to alcohol was therefore assessed in 4 groups: high/low aggressive SOMAS and high/low aggressive non-SOMAS. Results indicate that aggressive SOMAS had the highest intoxicated HR response and that they reported the most alcohol consumption. This suggests that in some cases the high comorbidity between alcohol misuse and aggression is related to an increased sensitivity to alcohol-induced reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)