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Roman high- and low-avoidance (RHA/Verh and RLA/Verh) rats are selected and bred for extreme divergence in two-way active avoidance acquisition. In addition, compared to RLA/Verh rats, RHA/Verh rats are (behaviorally and physiologically) less anxious or reactive to stressors, show increased novelty (sensation)-seeking behavior as well as a higher preference for rewarding substances, and are usually less efficient in learning tasks not involving shock administration. The present article reviews evidence showing that neonatal handling and/or environmental enrichment leads to enduring effects (their magnitude frequently depending upon the rat line) on those behaviors. For example, it has been found that neonatal handling reduces most of the (behavioral and physiological) signs of emotionality/anxiety in RLA/Verh rats, while environmental enrichment increases their novelty seeking (also the case with RHA/Verh rats), saccharin and ethanol intake, and sensitivity to amphetamine. Finally, initial results (currently being further elaborated upon) support a preventive action of both environmental treatments on age-related impairments in learning a spatial, water maze task as well as on hippocampal neuronal atrophy

Acquisition. --- Age-related impairments. --- Amphetamine. --- Avoidance. --- Behavior. --- Central amygdala. --- Early stimulation. --- Elevated plus-maze. --- Emotionality. --- Enrichment. --- Environmental enrichment. --- Ethanol. --- Female rats. --- Handling. --- Hippocampal. --- Impairments. --- Increase. --- Increases. --- Learning. --- Locomotor-activity. --- Low-avoidance rats. --- Neonatal handling. --- Neonatal. --- Neuroendocrine traits. --- Neuronal. --- Novelty-seeking. --- Novelty. --- Perinatal flumazenil. --- Physiological. --- Preference. --- Protein-kinase-c. --- Rat. --- Rats. --- Review. --- Roman high-and low-avoidance rats,reactivity to stress,anxiety,novelty/reward seeking,neonatal handling,enriched environment,age-related deficit,spatial learning,hippocampus. --- Seeking. --- Sensation-seeking. --- Sensitivity. --- Shock. --- Sign. --- Spatial. --- Stressor. --- Stressors. --- Task. --- Tasks. --- Treatment.

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Early neonatal handling of rat pups produces dampened hypothalamic-pituitary-adrenal axis reactivity to stress in adult male offspring. However, less is known about whether there is a similar effect for females. Although, most studies of neonatal handling have examined subsequent effects during adulthood, adolescence is an important developmental stage for stress responsivity. To address these issues, the effect of neonatal handling on the endocrine stress response and brain activity of male and female rats was determined in response to acute restraint stress during adolescence. Consistent with previous findings in adult males, neonatal handling reduced restraint stress-induced hormone levels in adolescent males. However, in contrast, we found elevated plasma hormone concentrations in handled females. A gender-specific handling effect on brain activity was also evident, with significantly increased stress-induced activation of the posterior cingulate cortex of handled females, as measured by c-fos mRNA expression. The striking gender difference in the effect of early neonatal handling provides evidence that this must be considered as an important variable in subsequent stress responsivity induced by early manipulations.

Activation. --- Activity. --- Adolescence. --- Adult. --- Adulthood. --- Brain. --- C-fos. --- Cortex. --- Corticosterone. --- Endocrine. --- Expression. --- Female rats. --- Female. --- Females. --- Gender. --- Handling. --- Hormone. --- Hypothalamic-pituitary-adrenal axis. --- Hypothalamic-pituitary-adrenal. --- Level. --- Male. --- Males. --- Neonatal handling. --- Neonatal. --- Plasma. --- Posterior cingulate cortex. --- Pups. --- Rat. --- Rats. --- Reactivity. --- Response. --- Restraint stress. --- Restraint. --- Sex differences. --- Stress reactivity. --- Stress response. --- Stress-response. --- Stress. --- Striking.

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Recent interest has focused on the advantage of intensively handling young foals as a means of producing more tractable horses, accustomed to humans and receptive to training. To date, the effect of this intensive handling, dubbed "imprint training" in the popular literature, has not been tested. The present study compares seven foals handled intensively as neonates with eight untreated controls. The handling protocol started from 2–8 h after birth and continued daily for a total of 5 days. The protocol consisted of a series of stimuli and experiences that were each repeated until the foal no longer resisted or reacted negatively. Subsequently, foals were tested before weaning, at 4 months of age. Results indicated that handled foals (HF) ranked higher than control foals (CF) in subjective ratings of calmness (*P<0.0117) and friendliness (***P<0.0001) and in several specific handling tasks (venipuncture *P<0.0220; placing in stock *P<0.0128). Although, in approach tests all foals but one allowed approach of a person to 4 m, significantly more HF approached the person than CF (**P<0.0080). In stimulus tests, foals were presented specific stimuli to which they had been tested as neonates. Two of eight CF were too unruly and dangerous to test. Of foals that could be tested, CF required significantly more time to hook-up a heart rate monitor (**P<0.0055). Split-plot analysis indicated that HF had lower heart rates to initial left-sided stimuli, presented first, than CF (*P<0.0421). In response to right-sided stimuli, heart rate scores of CF were not significantly different from HF (P<0.2259), suggesting reduced reactivity over time due to a learning effect. Behavioral responses to specific stimuli did not differ between CF and HF, suggesting that neonatal handling has a general rather than specific effect on subsequent behavior. Cortisol concentrations were measured before and after testing and the difference calculated. All foals had higher post-testing levels tha

Age. --- Analysis. --- Behavior. --- Behavioral-responses. --- Birth. --- Control. --- Cortisol. --- Dangerous. --- Experience. --- Foal. --- Foals. --- Handling. --- Heart rate. --- Heart-rate. --- Horse. --- Horses. --- Human. --- Humans. --- Imprint training. --- Investigation. --- Learning in foals. --- Learning. --- Level. --- Mechanisms. --- Neonatal foal handling. --- Neonatal handling. --- Neonatal. --- Neonates. --- Ratings. --- Reactivity. --- Response. --- Responses. --- Serum cortisol concentrations. --- Stimuli. --- Stimulus. --- Task. --- Tasks. --- Test. --- Tests. --- Time. --- Training. --- Weaning. --- Young.