Emotional reactivity and cognitive performance in aversively motivated tasks: a comparison between four rat strains

<p>Abstract</p> <p>Background</p> <p>Cognitive function might be affected by the subjects' emotional reactivity. We assessed whether behavior in different tests of emotional reactivity is correlated with performance in aversively motivated learning tasks, using four strains of rats generally considered to have a different emotional reactivity.</p> <p>Methods</p> <p>The performance of male Brown Norway, Lewis, Fischer 344, and Wistar Kyoto rats in open field (OF), elevated plus-maze (EPM), and circular light-dark preference box (cLDB) tasks, which are believed to provide measures of emotional reactivity, was evaluated. Spatial working and reference memory were assessed in two aversively motivated learning and memory tasks: the standard and the "repeated acquisition" versions of the Morris water maze escape task, respectively. All rats were also tested in a passive avoidance task. At the end of the study, levels of serotonin (5-HT) and <it>5</it>-hydroxyindoleacetic acid, and 5-HT turnover in the hippocampus and frontal cortex were determined.</p> <p>Results</p> <p>Strain differences showed a complex pattern across behavioral tests and serotonergic measures. Fischer 344 rats had the poorest performance in both versions of the Morris water escape task, whereas Brown Norway rats performed these tasks very well but the passive avoidance task poorly. Neither correlation analysis nor principal component analysis provided convincing support for the notion that OF, EPM, and cLDB tasks measure the <it>same </it>underlying trait.</p> <p>Conclusions</p> <p>Our findings do not support the hypothesis that the level of emotional reactivity modulates cognitive performance in aversively motivated tasks. Concepts such as "emotional reactivity" and "learning and memory" cannot adequately be tapped with only one behavioral test. Our results emphasize the need for multiple testing.</p

Effects of environmental enrichment on behavioral responses to novelty, learning, and memory, and the circadian rhythm in cortisol in growing pigs

Previously we showed that pigs reared in an enriched environment had higher baseline salivary cortisol concentrations during the light period than pigs reared under barren conditions. In the present experiment, it was investigated whether these higher baseline salivary cortisol concentrations were a real difference in cortisol concentration or merely represented a phase difference in circadian rhythm. The effects of different cortisol concentrations on the behavioral responses to novelty and learning and long-term memory in a maze test were also studied in enriched and barren housed pigs. At 9 weeks of age enriched and barren housed pigs did not differ in baseline salivary cortisol concentrations nor in circadian rhythm, but at 22 weeks of age barren housed pigs had a blunted circadian rhythm in salivary cortisol as compared to enriched housed pigs. The differences in baseline salivary cortisol concentrations between enriched- and barren-housed pigs are age-dependent, and become visible after 15 weeks of age. Enriched- and barren-housed piglets did not differ in time spent on exploration in the novel environment test. Barren-housed pigs had an impaired long-term memory in the maze test compared to enriched-housed pigs; however, no differences in learning abilities between enriched- and barren-housed pigs were found. Because blunted circadian cortisol rhythms are often recorded during states of chronic stress in pigs and rats or during depression in humans, it is suggested that the blunted circadian rhythm in cortisol in barren-housed pigs similarily may reflect decreased welfare.

Особенности процесса трещинообразования в массиве при управлении его газодинамикой

Исследован процесс сдерживания перехода угля из потенциально устойчивого состояния в стадию бурного разрушения. Ей, как правило, предшествует некоторый промежуток времени относительного затишья. Особенно важно улавливать этот момент среди массы различных откликов массива на ведение горных работ. Одним из вариантов управления развитием и релаксацией системы трещин может служить физико-химическая обработка.The inhibition process of coal transition from the potentially stable state in the stage of stormy destruction is investigation. As a rule, to it is preceded some interval of relative time calm. It is especially important to catch this moment among mass of different responses of array on the conduct of mountain works. Physical and chemical treatment can serve as one of control variants the development and relaxation of the cracks system

5-HT1A receptor blockade reverses GABAA receptor α3 subunit-mediated anxiolytic effects on stress-induced hyperthermia

Stress-related disorders are associated with dysfunction of both serotonergic and GABAergic pathways, and clinically effective anxiolytics act via both neurotransmitter systems. As there is evidence that the GABA(A) and the serotonin receptor system interact, a serotonergic component in the anxiolytic actions of benzodiazepines could be present. The main aim of the present study was to investigate whether the anxiolytic effects of (non-)selective alpha subunit GABA(A) receptor agonists could be reversed with 5-HT1A receptor blockade using the stress-induced hyperthermia (SIH) paradigm. The 5-HT1A receptor antagonist WAY-100635 (0.1-1 mg/kg) reversed the SIH-reducing effects of the non-alpha-subunit selective GABA(A) receptor agonist diazepam (1-4 mg/kg) and the GABA(A) receptor alpha(3)-subunit selective agonist TP003 (1 mg/kg), whereas WAY-100635 alone was without effect on the SIH response or basal body temperature. At the same time, co-administration of WAY-100635 with diazepam or TP003 reduced basal body temperature. WAY-100635 did not affect the SIH response when combined with the preferential alpha(1)-subunit GABA(A) receptor agonist zolpidem (10 mg/kg), although zolpidem markedly reduced basal body temperature. The present study suggests an interaction between GABA(A) receptor alpha-subunits and 5-HT1A receptor activation in the SIH response. Specifically, our data indicate that benzodiazepines affect serotonergic signaling via GABA(A) receptor alpha(3)-subunits. Further understanding of the interactions between the GABA(A) and serotonin system in reaction to stress may be valuable in the search for novel anxiolytic drugs

Fatigue in inflammatory rheumatic disorders : Pathophysiological mechanisms

Today, inflammatory rheumatic disorders are effectively treated, but many patients still suffer from residual fatigue. This work presents pathophysiological mechanisms of fatigue. First, cytokines can interfere with neurotransmitter release at the preterminal ending. Second, a long-term increase in serum concentrations of proinflammatory cytokines increase the uptake and breakdown of monoamines (serotonin, noradrenaline and dopamine). Third, chronic inflammation can also decrease monoaminergic neurotransmission via oxidative stress (oxidation of tetrahydrobiopterin [BH4]). Fourth, proinflammatory cytokines increase the level of enzyme indoleamine-2, 3-dioxygenase activity and shunt tryptophan away from the serotonin pathway. Fifth, oxidative stress stimulates astrocytes to inhibit excitatory amino acid transporters. Sixth, astrocytes produce kynurenic acid that acts as an antagonist on the α7-nicotinic acetylcholine receptor to inhibit dopamine release. Jointly, these actions result in increased glutamatergic and decreased monoaminergic neurotransmission. The above-described pathophysiological mechanisms negatively affect brain functioning in areas that are involved in fatigue

A robust animal model of state anxiety: fear-potentiated behaviour in the elevated plus-maze

Fear (i.e., decreased percentage time spent on open-arm exploration) in the elevated plus-maze can be potentiated by prior inescapable stressor exposure, but not by escapable stress. The use of fear-potentiated plus-maze behaviour has several advantages as compared to more traditional animal models of anxiety. (a) In contrast to the traditional (spontaneous) elevated plus-maze, which measures innate fear of open spaces, fear-potentiated plus-maze behaviour reflects an enhanced anxiety state (allostatic state). This ‘‘state anxiety’’ can be defined as an unpleasant emotional arousal in face of threatening demands or dangers. A cognitive appraisal of threat is a prerequisite for the experience of this type of emotion. (b) Depending on the stressor used (e.g., fear of shock, predator odour, swim stress, restraint, social defeat, predator stress (cat)), this enhanced anxiety state can last from 90 min to 3 weeks. Stress effects are more severe when rats are isolated in comparison to group housing. (c) Drugs can be administered in the absence of the original stressor and after stressor exposure. As a consequence, retrieval mechanisms are not affected by drug treatment. (d) Fear-potentiated plus-maze behaviour is sensitive to proven/putative anxiolytics and anxiogenics which act via mechanisms related to the benzodiazepine–gamma-aminobutyric acid receptor, but it is also sensitive to corticotropin-releasing receptor antagonists and glucocorticoid receptor antagonists and serotonin receptor agonists/antagonists complex (high predictive validity). (e) Fear-potentiated plus-maze behaviour is very robust, and experiments can easily be replicated in other labs. (f) Fear-potentiated plus-maze behaviour can be measured both in males and females. (g) Neural mechanisms involved in contextual fear conditioning, fear potentiation and state anxiety can be studied .Thus, fear-potentiated plus-maze behaviour may be a valuable measure in the understanding of neural mechanisms involved in the development of anxiety disorders and in the search for novel anxiolytics. Finally, the involvement of corticotropin-releasing factor and corticosteroid–corticotropin-releasing factor interactions in the production of fear-potentiated plus-maze behaviour are discussed.