Fluoxetine inhibits corticotropin-releasing factor (CRF)-induced behavioural responses in rats

Corticotropin-releasing factor (CRF) is a potent neuromodulator of stress-related behaviour but the neural mechanisms underlying these effects are not clear. Studies were designed to test the hypothesis that CRF-induced behavioural arousal involves interactions with brainstem serotonergic systems. To examine interactions between CRF and serotonergic systems in the regulation of behaviour, CRF (1 microg, intracerebroventricular (i.c.v.)) or vehicle was infused in the presence or absence of the selective serotonin re-uptake inhibitor fluoxetine (0, 0.1, 1 or 10 mg/kg, intravenous (i.v.)). Fluoxetine was used at these doses because it is known to decrease serotonin cell firing rates while increasing extracellular serotonin concentrations in select forebrain regions. We then measured behavioural, neurochemical and endocrine responses. CRF increased locomotion and spontaneous non-ambulatory motor activity (SNAMA) in the home cages. Fluoxetine decreased tissue 5-hydroxyindoleacetic acid concentrations, a measure of serotonin metabolism, in specific limbic brain regions of CRF-treated rats (nucleus accumbens shell region, entorhinal cortex, central nucleus of the amygdala). Furthermore, fluoxetine inhibited CRF-induced SNAMA. CRF and fluoxetine independently increased plasma corticosterone concentrations, but the responses had distinct temporal profiles. Overall, these data are consistent with the hypothesis that CRF-induced facilitation of behavioural activity is dependent on brainstem serotonergic systems. Therefore, fluoxetine may attenuate or alleviate some behavioural responses to stress by interfering with CRF-induced responses.     

Accelerated cognitive aging in diabetic rats is prevented by lowering corticosterone levels

Diabetes and normal aging are both characterized by increases in levels of glucocorticoids. Because long-term exposure to elevated glucocorticoids can be detrimental to hippocampal function, we evaluated the performance of young diabetic rats in the 14-unit T-maze, a task that is sensitive to hippocampal deficits. To assess the contribution of diabetes-induced elevations in corticosterone levels, we examined maze learning in diabetic rats that had levels of corticosterone 'clamped' through adrenalectomy and low-dose corticosterone replacement. For comparison, we also tested a separate group of young and aged rats in the maze. Adrenally intact diabetic rats learned poorly in the 14-unit T-maze. Preventing the increases in corticosterone levels that accompanies the onset of experimental diabetes also prevented deficits in complex maze learning. The pattern of errors made by adrenally intact diabetic rats was similar to the pattern of errors made by aged rats, suggesting that the cognitive profiles of diabetic and aged rats share common features.     

Book review

The American Journal of Psychoanalysis -     

Neutralizing Music Piracy: An Empirical Examination

The current study sought to test the viability of employing Sykes and Matza's (1957 Sykes , G. and D. Matza . 1957 . “Techniques of Neutralization: A Theory of Delinquency.” American Sociological Review 22 : 664 – 670 .[Crossref], [Web of Science ®] , [Google Scholar]) techniques of neutralization as a framework for understanding online music piracy. Using data from a sample of 2,032 undergraduates from a large Midwestern university, the relevance of neutralization theory is tested via multinomial logistic regression while controlling for other theoretical predictors and demographic variables. The findings indicated that greater acceptance of the techniques associated with denial of responsibility, denial of injury, denial of victim, and appeal to higher loyalties significantly predicted moderate levels of piracy participation. Furthermore, the effect of appeals to higher loyalty on piracy was found to be conditioned by the respondent's approval of the behavior. Overall, results suggested that university settings may unwittingly facilitate a climate for online piracy whereby students place a higher value on group norms rather than legal norms and do not consider the harms associated with the behavior.     

Biased processing of sad faces: An ERP marker candidate for depression susceptibility

Depression has been associated with task-relevant increased attention toward negative information, reduced attention toward positive information, or reduced inhibition of task-irrelevant negative information. This study employed behavioural and psychophysiological measures (event-related potentials; ERP) to examine whether groups with risk factors for depression (past depression, current dysphoria) would show attentional biases or inhibitory deficits related to viewing facial expressions. In oddball task blocks, young adult participants responded to an infrequently presented target emotion (e.g., sad) and inhibited responses to an infrequently presented distracter emotion (e.g., happy) in the context of frequently presented neutral stimuli. Previous depression was uniquely associated with greater P3 ERP amplitude following sad targets, reflecting a selective attention bias. Also, dysphoric individuals less effectively inhibited responses to sad distracters than non-dysphoric individuals according to behavioural data, but not psychophysiological data. Results suggest that depression risk may be most reliably characterised by increased attention toward others' depressive facial emotion.