Physiology & behavior
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Physiology & behavior · May 2012
TRPM2 channel protective properties of N-acetylcysteine on cytosolic glutathione depletion dependent oxidative stress and Ca2+ influx in rat dorsal root ganglion.
N-acetylcysteine (NAC) is a thiol-containing (sulphydryl donor) antioxidant, which contributes to regeneration of glutathione (GSH) and also acts through a direct reaction with free radicals. Thiol depletion has been implicated in the neurobiology of sensory neurons and pain. We reported recently an activator role of intracellular GSH depletion on calcium influx through transient receptor potential melastatin-like 2 (TRPM2) channels in rat dorsal root ganglion (DRG). ⋯ In conclusion, we observed a modulator role of NAC on Ca(2+) influx through a TRPM2 channel in intracellular GSH depleted DRG neurons. NAC incubation before BSO exposure appears to be more protective than NAC incubation after BSO exposure. Since cytosolic thiol group depletion is a common feature of neuropathic pain, our findings are relevant to the etiology and treatment of pain neuropathology in DRG neurons.
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Physiology & behavior · Apr 2012
ReviewMediators of allostasis and systemic toxicity in bipolar disorder.
Bipolar disorder is associated with a high rate of medical and psychiatric comorbidities. This burden of illness, along with cognitive impairment, is seen particularly in late cases, after multiple episodes. These changes in clinical presentation that take place over time have been recently conceptualized as "neuroprogression". ⋯ Allostatic load is engendered by several factors which interact in a nonlinear manner. Glucocorticoids are fundamental mediators; when chronically in excess, glucocorticoids initiate a series of bodily dysfunctions that may include cortisol-related mitochondrial dysfunction, oxidative stress, inflammation and decrease in the expression of neuroprotective factors. In the present review we examine the role of allostatic load in the illness progression that takes place in bipolar disorder.
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Physiology & behavior · Apr 2012
The salivary alpha amylase over cortisol ratio as a marker to assess dysregulations of the stress systems.
Different factors have been associated with changes in the regulation of the two major stress response systems of the human body, the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis. Changes in these systems have been associated with various (psycho)pathologies across adulthood, and are thus frequently assessed within the context of allostatic load. Early Life Adversity (ELA) has been identified as one such factor. ⋯ Using a specific formula to determine the ratio of sAA over cortisol, we found a systematically stronger positive relationship with indexes of chronic stress and depression when compared to cortisol over sAA, or either marker alone. Our findings suggest that the ratio of sAA over cortisol might be a better marker of stress systems dysregulation than the ratio of cortisol over sAA, sAA or cortisol alone. The usefulness of this marker for other chronic stress states as found in allostatic load is discussed.
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Physiology & behavior · Mar 2012
Genetic differences in temperament determine whether lavender oil alleviates or exacerbates anxiety in sheep.
Growing concerns about the risk of addiction to benzodiazepines have led to increasing interest in alternative therapies to treat anxiety and depression. Lavender oil (Lavendula augustifolia) is reportedly anxiolytic in a number of species but little is known about how it affects individuals that are more or less anxious when faced with a stressor. In this study, we used changes in locomotor activity and the plasma concentrations of cortisol to test whether lavender oil would reduce behavioral and endocrine correlates of anxiety in calm and nervous sheep exposed to an isolation stressor. ⋯ Exposure of calm sheep to lavender oil decreased the agitation score (P<0.001), frequency of vocalizations (P<0.05), decreased the number of crosses of the central lines of the isolation box (P<0.05), and the plasma concentrations of cortisol prior to isolation (P<0.05) (after mask application) compared to calm control sheep. Exposure of nervous sheep to lavender oil increased the frequency of vocalizations (P<0.05), the number of sheep attempting to escape (P<0.05) and the plasma concentrations of cortisol 30 min after isolation (P<0.05) compared to nervous control sheep. We conclude that genetic differences in temperament determine whether lavender oil alleviates or exacerbates the behavioral and/or endocrine correlates of anxiety in sheep.
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Physiology & behavior · Feb 2012
Optimizing reliability and sensitivity of Semmes-Weinstein monofilaments for establishing point tactile thresholds.
Semmes-Weinstein monofilaments (SWM) are widely used to assess tactile point pressure sensitivity. However, the reliability of SWMs has been questioned, standardization of stimulus presentation procedures is lacking, and the sensitivity measure is commonly confounded by the response criterion. This study sought to assess the reliability of two versions of a forced-choice single staircase SWM test with the goal of optimizing test reliability with a minimum number of test trials. ⋯ The threshold values correlated with subject age despite the small range of ages tested, suggesting high sensitivity (Sessions 1 and 2 rs=0.61 and 0.63, ps<0.001). This study demonstrates that SWMs provide highly reliable and sensitive point pressure thresholds with very few trials when an appropriate psychophysical paradigm is employed. The brief forced-choice procedure described herein could serve as a basis for standardizing SWM stimulus presentation methods.