Differential effects of stress on escape and reflex responses to nociceptive thermal stimuli in the rat

Environmental Enrichment Reverses Behavioral Alterations in Rats Prenatally Exposed to Valproic Acid: Issues for a Therapeutic Approach in Autism

“…This profile is in concordance with previous studies, which indicate a weak effect of enrichment on behavioral and physiological parameters in 'naïve' animals (van Praag et al, 2000;Schrijver et al, 2002). On the basis of the present data, we would suggest that lower anxiety in VPA rats subjected to environmental enrichment in the early stage of life may conduct to increased exploration, normalized locomotor and repetitive/stereotypic activity, and attenuated nociceptive and tactile thresholds, as fear and anxiety have profound influence on these parameters in animals (eg King et al, 2003;da Silva Torres et al, 2003;Palermo-Neto et al, 2003;Knott and Hutson, 1982). Enhanced repetitive/ stereotypic-like activity is associated with many neurodevelopmental disorders in humans (eg autism), and often observed under conditions of environmental restriction in animals.…”

Regular physical activity prevents development of chronic pain and activation of central neurons

“…It should be noted that all prior studies in animal models of pain used forced exercise, which may produce analgesia through a stress response. It is well-known that stress can produce analgesia without the exercise task (4,25,31,32). The current study was the first to use voluntary running wheel activity in animal models of pain, which allowed mice to choose when and if they wanted to run, thus eliminating stress as a confounder.…”

Prenatal exposure to valproic acid disturbs the enkephalinergic system functioning, basal hedonic tone, and emotional responses in an animal model of autism

“…Noteworthy, the observed aberrations were reversed by an environmental enrichment procedure (Schneider et al 2006). Environmental enrichment had been previously shown to decrease anxiety in rodents (Levine 1962(Levine , 1967, whereas fear and anxiety have a profound influence on behaviors found to be aberrant in VPA rats (e.g., Belzung 1992;King et al 2003;da Silva Torres et al 2003;Palermo-Neto et al 2003;Knott and Hutson 1982;Vanderschuren et al 1995;Haller et al 2003;Haller and Bakos 2002;File and Hyde 1978). Thus, the behavioral profile observed in VPA rats might suggest disturbed functioning of systems controlling reactions to stressful stimuli.…”