Maternal effects on the development of spontaneous hypertension

Cross-fostering spontaneously hypertensive rat (SHR) pups to Wistar-Kyoto (WKY) normotensive mothers influenced physical development, resting mean arterial pressure and heart rate, open-field behavior, and sympathetic-adrenal medullary responses to stressors. In contrast, cross-fostering WKY pups to SHR mothers at birth did not affect these developmental processes.     

When inclusion hurts: The role of valence in moderating the effects of being in the loop

We explored conditions under which being in the loop may be an undesirable experience. We tested whether information valence moderates the effects of being in versus out of the loop in four studies. In a pilot study, participants imagined positive and negative events and indicated the degree to which they would like to know this information. In Study 1, participants imagined being in or out of the loop on positive or negative information and indicated how they would feel. In Study 2, participants relived an actual experience when they were in or out of the loop on positive or negative information. In Study 3, participants were in or out of the loop on positive or negative information needed for an upcoming task. These studies provide evidence that being in the loop on negative information can be an unenjoyable experience, threatening fundamental needs and increasing negative affect.     

Connecting in the Twitterverse: Using Twitter to satisfy unmet belonging needs

The current study explored how social media can satisfy unmet needs for belonging. We predicted that, of those who experience chronic ostracism (feeling excluded and ignored frequently), people high in need to belong would utilize Twitter to satisfy their unmet belonging needs more than those low in need to belong. Specifically, individuals high in need to belong and chronic ostracism should use Twitter to form and maintain parasocial relationships (one-sided relationships with media figures). Participants (n = 315) completed a survey assessing their chronic ostracism experiences, dispositional need to belong, and Twitter behavior, particularly regarding potential parasocial relationship targets (n = 229). As expected, when participants reported experiencing high rates of chronic ostracism, participants high in need to belong used Twitter more than those low in need to belong, particularly following more parasocial relationship targets. Thus, maintaining parasocial relationships on Twitter may be an effective way to satisfy unmet belonging needs.     

Enhanced release of norepinephrine in rat hippocampus during spontaneous alternation tests

Recent evidence suggests that release of acetylcholine (ACh) in the hippocampus is associated with performance on a spontaneous alternation task and with enhancement of that performance by systemic and central injections of glucose. The present study extended these findings by examining norepinephrine (NE) release in the hippocampus using in vivo microdialysis while rats were tested for spontaneous alternation performance with and without prior injections (ip) of glucose. Microdialysis samples were collected every 12 min and assayed for NE content by HPLC-ECD. Like ACh, NE release in hippocampus increased during spontaneous alternation testing. As in past experiments, administration of glucose (250 mg/kg) significantly enhanced alternation scores. However, glucose did not influence NE release either during behavioral testing or at rest. These findings contrast with prior evidence showing that glucose augments testing-related increases in ACh release. The findings suggest that norepinephrine is released within the hippocampus while rats are engaged in alternation performance. However, increased release of norepinephrine apparently does not contribute to the enhancement of alternation scores produced by glucose.     

Open-field behavior of spontaneously hypertensive and Wistar-Kyoto normotensive rats: effects of reciprocal cross-fostering

The influence of the maternal environment on the development of open-field behavior in spontaneously hypertensive (SHR) rats was investigated using the technique of reciprocal cross-fostering. Entire litters of SHR and Wistar-Kyoto (WKY) normotensive rats were either reared by their natural mothers, in-fostered to dams of the same strain, or cross-fostered to dams of the opposite strain on the day after birth. Open-field behavior was assessed in male and female rats from the six groups (2 strains x 3 rearing conditions) at 30, 60, 90, and 120 days of age. Animals were observed in the open-field during a 5-min test period and the number of squares entered and hindlimb rears were recorded. At all ages tested, SHR rats were more active in the open field, entering more squares and rearing more frequently than WKYs. SHR females were more active than age-matched SHR males, while no sex differences were apparent in the WKY strain. At each age, open-field behavior was similar across WKY rearing groups. SHR control and in-fostered animals responded similarly in the open field; however, SHR cross-fostered rats (particularly females) tended to be more active than controls. Although cross-fostering has profound effects on cardiovascular development and functioning in the SHR, it appears that altering the early maternal environment experienced by SHR pups does not grossly affect the development of open-field behavior.     

Depressive Symptoms Among Delinquent Youth: Testing Models of Association with Stress and Support

The high prevalence of depression among incarcerated youth indicates a need to better understand factors that contribute to depression within this vulnerable subgroup. Previous research in general community samples has suggested that high levels of stress and low levels of parental support are associated with depression in young people, but it is unclear whether or how they might be associated with depression among incarcerated youth who are already vulnerable. Using a sample of 228 adolescents (aged 13–18 years) who were detained in the juvenile justice system, stress and support were modeled as independent main effects and as interactive risk factors in relation to depressive symptoms. More stressful life events and less caregiver support were each independently associated with depressive symptoms, but no evidence was found for the buffering hypothesis in this sample. Stressful life events were more strongly associated with depressive symptoms among boys compared to girls.     

Callous-Unemotional Traits as Unique Prospective Risk Factors for Substance Use in Early Adolescent Boys and Girls

Youth with elevated conduct disorder (CD) symptoms who also have callous-unemotional (CU) traits exhibit more antisocial behavior than youth without CU traits. However, evidence regarding whether CU traits increase risk of substance use over and above CD symptoms, and whether these associations differ for boys and girls, is scarce. Using the Developmental Pathways Project sample of 521 middle school students, we examined whether adolescent- and parent-reported CU traits measured in 6th grade prospectively predicted the onset and recurrence of substance use and use-related impairment by 9th grade. We also examined the degree to which CU traits uniquely predicted substance use and impairment over and above CD symptoms, as well as whether gender moderated these associations. Results indicated that adolescent-reported CU traits increased the likelihood of substance use and impairment onset and recurrence by 9th grade. Analyses revealed that CD symptoms accounted for prospective associations between adolescent-reported CU and substance use, but gender moderated these associations. Boys with elevated CU traits and CD symptoms were not more likely to report alcohol use onset or recurrence, but they were at highest risk of recurrent marijuana use, use of both alcohol and marijuana, and use-related impairment by 9th grade. Girls with low CU traits and high CD symptoms were most likely to report onset and recurrent use of alcohol, as well as recurrent marijuana use, use of both substances and impairment. Study findings highlight the importance of accounting for CD symptoms and gender when examining links between CU traits and substance use in early adolescence.     

Stranger Danger: The Role of Perpetrator and Context in Moderating Reactions to Sexual Harassment

The majority of research on sexual harassment focuses on achievement contexts where the perpetrator of the harassment is known to the victim. More recent work has begun to explore sexual harassment perpetrated by strangers in public places. The current work sought to bridge the gap between research on sexual harassment in achievement contexts and stranger harassment. In doing so, the current work manipulated factors related to three important distinctions between these topics: the relationship between the perpetrator and victim, the location, and the type of sexually harassing behavior. The current study provides evidence that stranger harassment elicits more negative reactions than harassment from a coworker. Additionally, harasser type interacted with harassment type, with situations involving strangers making physical contact eliciting the most negative reactions. Thus, the current work suggests a need for more research on stranger harassment, as well as on additional factors that may operate differently depending on harasser type.     

Fluctuations in brain glucose concentration during behavioral testing: dissociations between brain areas and between brain and blood

Traditional beliefs about two aspects of glucose regulation in the brain have been challenged by recent findings. First, the absolute level of glucose in the brain's extracellular fluid appears to be lower than previously thought. Second, the level of glucose in brain extracellular fluid is less stable than previously believed. In vivo brain microdialysis was used, according to the method of zero net flux, to determine the basal concentration of glucose in the extracellular fluid of the striatum in awake, freely moving rats for comparison with recent hippocampal measurements. In addition, extracellular glucose levels in both the hippocampus and the striatum were measured before, during, and after behavioral testing in a hippocampus-dependent spontaneous alternation task. In the striatum, the resting extracellular glucose level was 0.71 mM, approximately 70% of the concentration measured previously in the hippocampus. Consistent with past findings, the hippocampal extracellular glucose level decreased by up to 30 +/- 4% during testing; no decrease, and in fact a small increase (9 +/- 3%), was seen in the striatum. Blood glucose measurements obtained during the same testing procedure and following administration of systemic glucose at a dose known to enhance memory in this task revealed a dissociation in glucose level fluctuations between the blood and both striatal and hippocampal extracellular fluid. These findings suggest, first, that glucose is compartmentalized within the brain and, second, that one mechanism by which administration of glucose enhances memory performance is via provision of increased glucose supply from the blood specifically to those brain areas involved in mediating that performance.