Physiology & behavior
-
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.
-
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.
-
Physiology & behavior · Feb 2012
Availability of a rich source of sodium during the perinatal period programs the fluid balance restoration pattern in adult offspring.
Osmoregulatory mechanisms can be vulnerable to electrolyte and/or endocrine environmental changes during the perinatal period, differentially programming the developing offspring and affecting them even in adulthood. The aim of this study was to evaluate whether availability of hypertonic sodium solution during the perinatal period may induce a differential programming in adult offspring osmoregulatory mechanisms. With this aim, we studied water and sodium intake after Furosemide-sodium depletion in adult offspring exposed to hypertonic sodium solution from 1 week before mating until postnatal day 28 of the offspring, used as a perinatal manipulation model [PM-Na group]. ⋯ Moreover, along the brainstem, we found a decreased number of sodium depletion-activated cells within the nucleus of the solitary tract of the PM-Na group. Our data indicate that early sodium availability induces a long-term effect on fluid drinking and on the cell activity of brain nuclei involved in the control of hydromineral balance. These results also suggest that availability of a rich source of sodium during the perinatal period may provoke a larger anticipatory response in the offspring, activating the vasopressinergic system and reducing thirst after water and sodium depletion, as a result of central osmosensitive mechanism alterations.
-
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.
-
Physiology & behavior · Jan 2012
Lateralized amygdala activation: importance in the regulation of anxiety and pain behavior.
The amygdala is involved in the emotional responses to fear including anxiety and heightened pain reporting. In a rodent model, bilateral activation of the central amygdala (CeA) with corticosterone (CORT) produces anxiety-like behavior, somatic allodynia and visceral hypersensitivity. Although hemisphere-specific processing differences between the left and right amygdala have been reported, it remains unclear whether the right or left CeA is involved in the production of anxiety-like behavior, and abnormal somatic and visceral perception. The goal of the present study was to investigate the hypothesis that lateralized corticoid-mediated mechanisms in the CeA produce anxiety as well as abnormal pain perception. ⋯ These results provide evidence that there is no hemispheric lateralization of the CeA involved in corticoid-mediated anxiety-like behavior and heightened pain reporting.