Physiology & behavior
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Physiology & behavior · Sep 2015
Male adolescent rats display blunted cytokine responses in the CNS after acute ethanol or lipopolysaccharide exposure.
Alcohol induces widespread changes in cytokine expression, with recent data from our laboratory having demonstrated that, during acute ethanol intoxication, adult rats exhibit consistent increases in interleukin (IL)-6 mRNA expression in several brain regions, while showing reductions in IL-1 and TNFα expression. Given evidence indicating that adolescence may be an ontogenetic period in which some neuroimmune processes and cells may not yet have fully matured, the purpose of the current experiments was to examine potential age differences in the central cytokine response of adolescent (P31-33days of age) and adult (69-71days of age) rats to either an acute immune (lipopolysaccharide; LPS) or non-immune challenge (ethanol). In Experiment 1, male Sprague-Dawley rats were given an intraperitoneal (i.p.) injection of either sterile saline, LPS (250μg/kg), or ethanol (4-g/kg), and then trunk blood and brain tissue were collected 3h later for measurement of blood ethanol concentrations (BECs), plasma endotoxin, and central mRNA expression of several immune-related gene targets. ⋯ Analysis of BECs indicated that, for both routes of exposure, adolescents exhibited lower BECs than adults. Taken together, these data suggest that categorically different mechanisms are involved in the central cytokine response to antigen exposure versus ethanol administration. Furthermore, these findings confirm once again that acute ethanol intoxication is a potent activator of brain cytokines, and calls for future studies to identify the mechanisms underlying age-related differences in the cytokine response observed during ethanol intoxication.
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Physiology & behavior · Jun 2015
Pain perception and EEG dynamics: does hypnotizability account for the efficacy of the suggestions of analgesia?
We report novel findings concerning the role of hypnotizability, suggestions of analgesia and the activity of the Behavioral Inhibition/Activation System (BIS/BAS) in the modulation of the subjective experience of pain and of the associated EEG dynamics. The EEG of high (highs) and low hypnotizable participants (lows) who completed the BIS/BAS questionnaire was recorded during basal conditions, tonic nociceptive stimulation without (PAIN) and with suggestions for analgesia (AN). Participants scored the perceived pain intensity at the end of PAIN and AN. ⋯ The decreased midline cortical Determinism observed during nociceptive stimulation in both groups independently of suggestions remained significantly reduced only in lows after controlling for the activity of the Behavioral Activation System. Finally, controlling for the activity of the Behavioral Inhibition System abolished stimulation, suggestions and hypnotizability-related differences. Results indicate that the BIS/BAS activity may be more important than hypnotizability itself in pain modulation and in the associated EEG dynamics.
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Physiology & behavior · Jun 2015
Exercise but not (-)-epigallocatechin-3-gallate or β-alanine enhances physical fitness, brain plasticity, and behavioral performance in mice.
Nutrition and physical exercise can enhance cognitive function but the specific combinations of dietary bioactives that maximize pro-cognitive effects are not known nor are the contributing neurobiological mechanisms. Epigallocatechin-3-gallate (EGCG) is a flavonoid constituent of many plants with high levels found in green tea. EGCG has anti-inflammatory and anti-oxidant properties and is known to cross the blood brain barrier where it can affect brain chemistry and physiology. β-Alanine (B-ALA) is a naturally occurring β-amino acid that could increase cognitive functioning by increasing levels of exercise via increased capacity of skeletal muscle, by crossing the blood brain barrier and acting as a neurotransmitter, or by free radical scavenging in muscle and brain after conversion into carnosine. ⋯ Running increased food intake, decreased fat mass, increased time to exhaustive fatigue, increased numbers of new cells in the granule layer of the hippocampus, and enhanced retrieval of both contextual and cued fear memories. The diets had no effect on their own or in combination with exercise on any of the fitness, plasticity, and behavioral outcome measures other than B-ALA decreased percent body fat whereas EGCG increased lean body mass slightly. Results suggest that, in young adult BALB/cJ mice, a 39day treatment of exercise but not dietary supplementation with B-ALA or EGCG enhances measures of fitness, neuroplasticity and cognition.
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Physiology & behavior · Jun 2015
Co-occurrence of anxiety and depressive-like behaviors following adolescent social isolation in male mice; possible role of nitrergic system.
Approximately more than 50% of patients with depression have the co-occurrence of anxiety, which complicates the treatment of disease. Recently, social isolation stress (SIS) paradigm has been suggested as an animal model to investigate the underlying mechanism involved in depression-anxiety co-occurrence. In this study, applying six weeks of SIS to adolescent mice, we tested whether nitrergic system plays a role in co-occurrence of depression and anxiety. ⋯ Administration of subeffective doses of aminoguanidine (a specific inducible nitric oxide synthase inhibitor or iNOS, 50mg/kg) and L-NAME (non-specific inhibitor of NOS, 10mg/kg) significantly reversed the negative effects of SIS on behavioral profile as well as nitrite levels in the cortex of IC mice, Although administration of subeffective dose of 7-nitroindazole (a specific neuronal NOS inhibitor, 25mg/kg) decreased the nitrite levels in the hippocampus, but had no effect on depressant and anxiogenic effects of SIS. Results of this study confirmed that SIS is an appropriate animal model to investigate the potential mechanisms in depression-anxiety co-occurrence. We also showed that nitrergic system has contributed to co-occurrence of depression and anxiety in IC mice as an underlying mechanism.
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Physiology & behavior · May 2015
Strain-dependent effects on acquisition and reversal of visual and spatial tasks in a rat touchscreen battery of cognition.
The use of touch-screen equipped operant boxes is an increasingly popular method for modeling human cognition in the rodent. A concern of this approach is that the dependence upon vision may limit the strains of rats that can be tested in the apparatus. This is of particular concern because of the increased availability of genetically modified rats that are disproportionately on an albino background and may have compromised vision. Here we test pigmented and albino strains of rats on three touch-screen tasks of learning and memory that may require different levels of visual ability. In tests where albino animals have similar levels of performance as the pigmented rats we also tested common pharmacological models of cognitive impairment to determine the generalizability of these challenges across strains. By doing this work we hope to determine the robustness of common models of pharmacological impairment in albino rats. ⋯ Albino animals showed a clear impairment on tasks that are dependent upon intact vision, while no impairment was observed in the visually less demanding spatial task. Despite a published report to the contrary, these results demonstrate that albino strains may not be appropriate for use in touchscreen tasks that are dependent upon a visual discrimination. Furthermore, the spatial search task showed distinct impairment profiles as a result of treatment with either MK-801 or scopolamine. While an interaction did exist between strain and treatment, the dissociation between MK-801 and scopolamine was consistent across 3 of 4 strains. These results highlight the importance of selecting the appropriate strain for use in tasks of visual learning and memory and also demonstrate the potential robustness of pharmacological models of cognitive impairment across strains.