Physiology & behavior
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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.
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Physiology & behavior · Feb 2012
Effects of pretraining treatment with testosterone on successive and anticipatory negative contrast.
Previous research indicated that the suppression of consummatory behavior that follows incentive downshift in male rats is attenuated by testosterone (T) administration during training. The present experiments were designed to assess the role of pretraining T administration on two incentive contrast situations in consummatory behavior: successive negative contrast (cSNC) and anticipatory negative contrast (cANC). In cSNC (Experiment 1), a downshift from 32% to 4% sucrose leads to behavioral suppression relative to an unshifted, 4% sucrose condition (the cSNC effect). ⋯ Consumption of 4% sucrose is suppressed when the second bottle offers 32% sucrose, relative to 4% sucrose (the cANC effect). Pretraining T did not affect the cANC effect, known to be insensitive to treatment with anxiolytics. These results suggest an anxiolytic-like effect of testosterone in adjustment to incentive downshifts.
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Physiology & behavior · Feb 2012
Pain behavior and spinal cell activation due to carrageenan-induced inflammation in two inbred rat strains with differential hypothalamic-pituitary-adrenal axis reactivity.
Lewis (LEW) and Fischer (FIS) inbred rats were used to study the relationship of hypothalamic-pituitary-adrenal (HPA) axis reactivity with inflammation-related pain behavior. LEW rats are susceptible to the development of autoimmune and chronic inflammatory disorders, whereas FIS rats are resistant. Since contradictory data have previously been collected under conditions of acute inflammation, we investigated the onset and maintenance of thermal and mechanical hyperalgesia and spinal activation of neurons and glia cells in a model of ongoing inflammation in both strains. ⋯ Our results suggest a biphasic role of the HPA axis in pain behavior and spinal cell activation associated with ongoing inflammation. In the acute stage, the stronger reaction in FIS rats might be explained by an activating effect of corticosteroids on neutrophil function. Under ongoing inflammatory conditions the immunosuppressive actions of corticosteroids may dominate and lead to a quicker recovery of paw volume and pain sensitivity in FIS rats.
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Physiology & behavior · Jan 2012
Stress-induced enhancement of fear conditioning and sensitization facilitates extinction-resistant and habituation-resistant fear behaviors in a novel animal model of posttraumatic stress disorder.
Posttraumatic stress disorder (PTSD) is characterized by stress-induced symptoms including exaggerated fear memories, hypervigilance and hyperarousal. However, we are unaware of an animal model that investigates these hallmarks of PTSD especially in relation to fear extinction and habituation. Therefore, to develop a valid animal model of PTSD, we exposed rats to different intensities of footshock stress to determine their effects on either auditory predator odor fear extinction or habituation of fear sensitization. ⋯ In addition, Experiment 4 indicated that without delivery of nonassociative auditory clicks, 0.8 mA footshock stressed rats did not exhibit robust increases in sensitized freezing and locomotor hyperactivity, albeit head out vigilance-like behavior continued to be observed. In summary, our animal model provides novel information on the effects of different intensities of footshock stress, auditory-predator odor fear conditioning, and their interactions on facilitating either extinction-resistant or habituation-resistant fear-related behavior. These results lay the foundation for exciting new investigations of the hallmarks of PTSD that include the stress-induced formation and persistence of traumatic memories and sensitized fear.
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Physiology & behavior · Jan 2012
Obese adolescents with eating disorders: analysis of metabolic and inflammatory states.
The purpose of the present investigation was to compare the effect of interdisciplinary therapy on the physical and metabolic profiles, including body composition, insulin resistance and sensitivity as well as adiponectin and leptin concentrations, of obese adolescents with and without eating disorder symptoms. ⋯ The eating disorder symptoms did not impair the metabolic state during weight loss therapy of obese adolescents. Additionally, long-term interdisciplinary therapy was effective in reducing the chances of developing several co-morbidities in both groups.