Active avoidance learning differentially activates ERK phosphorylation in the primary auditory and visual cortices of Roman high- and low-avoidance rats.

Understanding the mechanisms underlying conditioned avoidance is a critical step toward the development of novel treatments of anxiety. In this context, the two-way active avoidance (2WAA) task is a validated paradigm to investigate uncontrolled avoidance, a hallmark of anxiety disorders. The outbred Roman high- (RHA) and low-avoidance (RLA) rat lines are selected for respectively rapid vs.

Effect of Acute Stress on the Expression of BDNF, trkB, and PSA-NCAM in the Hippocampus of the Roman Rats: A Genetic Model of Vulnerability/Resistance to Stress-Induced Depression.

The Roman High-Avoidance (RHA) and the Roman Low-Avoidance (RLA) rats, represent two psychogenetically-selected lines that are, respectively, resistant and prone to displaying depression-like behavior, induced by stressors. In the view of the key role played by the neurotrophic factors and neuronal plasticity, in the pathophysiology of depression, we aimed at assessing the effects of acute stress, i.e.

Effects of morphine on place conditioning and ERK phosphorylation in the nucleus accumbens of psychogenetically selected Roman low- and high-avoidance rats.

Rationale: Extracellular signal-regulated kinase (ERK) phosphorylation is critical for neuronal and behavioural functions; in particular, phosphorylated ERK (pERK) expression in the nucleus accumbens (Acb) of the rat is stimulated by addictive drugs with the exception of morphine, which decreases accumbal ERK phosphorylation in the Sprague-Dawley and Wistar rats. The psychogenetically selected Roman low- (RLA) and high-avoidance (RHA) rats differ behaviourally and neurochemically in many responses to addictive drugs. In particular, morphine elicits a greater increment in locomotor activity and in dopamine transmission in the Acb of RHA vs RLA rats.

Differential effects of antipsychotic and propsychotic drugs on prepulse inhibition and locomotor activity in Roman high- (RHA) and low-avoidance (RLA) rats.

Rationale: Animal models with predictive and construct validity are necessary for developing novel and efficient therapeutics for psychiatric disorders.

Objectives: We have carried out a pharmacological characterization of the Roman high- (RHA-I) and low-avoidance (RLA-I) rat strains with different acutely administered propsychotic (DOI, MK-801) and antipsychotic drugs (haloperidol, clozapine), as well as apomorphine, on prepulse inhibition (PPI) of startle and locomotor activity (activity cages).

Results: RHA-I rats display a consistent deficit of PPI compared with RLA-I rats.

Effects of Forced Swimming Stress on ERK and Histone H3 Phosphorylation in Limbic Areas of Roman High- and Low-Avoidance Rats.

Stressful events evoke molecular adaptations of neural circuits through chromatin remodeling and regulation of gene expression. However, the identity of the molecular pathways activated by stress in experimental models of depression is not fully understood. We investigated the effect of acute forced swimming (FS) on the phosphorylation of the extracellular signal-regulated kinase (ERK)1/2 (pERK) and histone H3 (pH3) in limbic brain areas of genetic models of vulnerability (RLA, Roman low-avoidance rats) and resistance (RHA, Roman high-avoidance rats) to stress-induced depression-like behavior.

Neonatal handling enduringly decreases anxiety and stress responses and reduces hippocampus and amygdala volume in a genetic model of differential anxiety: Behavioral-volumetric associations in the Roman rat strains.

The hippocampus and amygdala have been proposed as key neural structures related to anxiety. A more active hippocampus/amygdala system has been related to greater anxious responses in situations involving conflict/novelty. The Roman Low- (RLA) and High-avoidance (RHA) rat lines/strains constitute a genetic model of differential anxiety.

Divergent effects of isolation rearing on prepulse inhibition, activity, anxiety and hippocampal-dependent memory in Roman high- and low-avoidance rats: A putative model of schizophrenia-relevant features.

Social isolation of rats induces a constellation of behavioral alterations known as "isolation syndrome" that are consistent with some of the positive and cognitive symptoms observed in schizophrenic patients. In the present study we have assessed whether isolation rearing of inbred Roman high-avoidance (RHA-I) and Roman low-avoidance (RLA-I) strains can lead to the appearance of some of the key features of the "isolation syndrome", such as prepulse inhibition (PPI) deficits, increased anxious behavior, hyperactivity and memory/learning impairments. Compared to RLA-I rats, the results show that isolation rearing (IR) in RHA-I rats has a more profound impact, as they exhibit isolation-induced PPI deficits, increased anxiety, hyperactivity and long-term reference memory deficits, while isolated RLA-I rats only exhibit deficits in a spatial working memory task.

Involvement of dopamine in the differences in sexual behaviour between Roman high and low avoidance rats: an intracerebral microdialysis study.

Outbred Roman high- (RHA) and low-avoidance (RLA) rats are selected for respectively rapid vs. poor acquisition of the active avoidance response and display different copulatory patterns when exposed to a sexually receptive female, with RHA rats showing more robust sexual motivation and better performance than RLA rats also after repeated sexual activity. Here we show that the distinct patterns of sexual behaviour of the Roman lines are correlated with differences in the activity of the dopaminergic mesolimbic system, which plays a key role in sexual motivation and copulatory performance.

Dopamine is involved in the different patterns of copulatory behaviour of Roman high and low avoidance rats: studies with apomorphine and haloperidol.

Outbred Roman high- (RHA) and low-avoidance (RLA) rats, originally selected for rapid vs. poor acquisition of active avoidance in a shuttle box, show differential copulatory patterns when exposed to a receptive female. Indeed, in the first copulation test male RHA rats show more mounts, intromissions and ejaculations than RLA rats.

Male Roman high and low avoidance rats show different patterns of copulatory behaviour: comparison with Sprague Dawley rats.

Roman high- (RHA) and low-avoidance (RLA) rats, selectively bred for, respectively, rapid vs. extremely poor acquisition of avoidant behaviour in the shuttle-box, display different coping strategies when exposed to aversive environmental conditions: RLA rats are reactive copers and show hyperemotional behaviour characterized by hypomotility and freezing, while RHA rats show a proactive coping behaviour aimed at gaining control over the stressor. RHA rats also display a robust sensation/novelty seeking profile, high baseline levels of impulsivity, and marked preference for, and intake of, natural and drug rewards.

Dopamine agonist-induced penile erection and yawning: a comparative study in outbred Roman high- and low-avoidance rats.

The effects on penile erection and yawning of subcutaneous (SC) injections of the mixed dopamine D1/D2-like agonist apomorphine (0.02-0.2 mg/kg) were studied in outbred Roman high- (RHA) and low-avoidance (RLA) male rats, two lines selectively bred for their respectively rapid versus poor acquisition of the active avoidance response in the shuttle-box, and compared with the effects observed in male Sprague-Dawley (SD) rats.