Different addictive drug exposure induces selective alterations of the Endogenous Opioid System : modulation of transcription and epigenetic mechanisms

Drug addiction manifests clinically as compulsive drug seeking, and cravings that can persist and recur even after extended periods of abstinence. The fundamental principle that unites addictive drugs is that each one enhances synaptic DA by means that dissociate it from normal behavioral control, so that they act to reinforce their own acquisition. Our attention has focused on the study of phenomena associated with the consumption of alcohol and heroin. Alcohol has long been considered an unspecific pharmacological agent, recent molecular pharmacology studies have shown that acts on different primary targets. Through gene expression studies conducted recently it has been shown that the classical opioid receptors are differently involved in the consumption of ethanol and, furthermore, the system nociceptin / NOP, included in the family of endogenous opioid system, and both appear able to play a key role in the initiation of alcohol use in rodents. What emerges is that manipulation of the opioid system, nociceptin, may be useful in the treatment of addictions and there are several evidences that support the use of this strategy. The linkage between gene expression alterations and epigenetic modulation in PDYN and PNOC promoters following alcohol treatment confirm the possible chromatin remodeling mechanism already proposed for alcoholism. In the second part of present study, we also investigated alterations in signaling molecules directly associated with MAPK pathway in a unique collection of postmortem brains from heroin abusers. The interest was focused on understanding the effects that prolonged exposure of heroin can cause in an individual, over the entire MAPK cascade and consequently on the transcription factor ELK1, which is regulated by this pathway. We have shown that the activation of ERK1/2 resulting in Elk-1 phosphorylation in striatal neurons supporting the hypothesis that prolonged exposure to substance abuse causes a dysregulation of MAPK pathway.

Psychiatric comorbidity, Restless Legs Syndrome and Nocturnal Eating Disorder: a case-control study

Objective: to evaluate the psychopathological profile in primary Restless Legs Syndrome (p-RLS) patients with and without nocturnal eating disorder (NED), analysing obsessive-compulsive traits, mood and anxiety disorder, and the two domains of personality proposed by Cloninger, temperament and character. Methods: we tested ten p-RLS patients without NED, ten p-RLS patients with NED and ten healthy control subjects, age and sex-matched, using Hamilton Depression and Anxiety Rating Scales, State-Trait Anxiety Inventory, Maudsley Obsessive Compulsive Inventory (MOCI) and Temperament and Character Inventory - revised (TCI). Results: p-RLS patients, particularly those with NED, had increased anxiety factor scores. MOCI-total, doubting and checking compulsion, and TCI-harm avoidance scores were significantly higher in p-RLS patients with NED. p-RLS patients without NED had significantly higher MOCI-doubting scores and a trend toward higher checking compulsion and harm avoidance scores with an apparent grading from controls to p-RLS patients without NED to p-RLS with NED. Conclusions: higher harm avoidance might predispose to display obsessive-compulsive symptoms, RLS and then, with increasing severity, compulsive nocturnal eating. RLS and NED could represent a pathological continuum in which a dysfunction in the limbic system, possibly driven by a dopaminergic dysfunction, could be the underlying pathophysiological mechanism.