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The STriatal-Enriched protein tyrosine Phosphatase (STEP) is a brain-specific phosphatase whose dysregulation in expression and/or activity is associated with several neuropsychiatric disorders. We recently showed that long-term excessive consumption of ethanol induces a sustained inhibition of STEP activity in the dorsomedial striatum (DMS) of mice. We further showed that down-regulation of STEP expression in the DMS, and not in the adjacent dorsolateral striatum, increases ethanol intake, suggesting that the inactivation of STEP in the DMS contributes to the development of ethanol drinking behaviors. Here, we compared the consequence of global deletion of the STEP gene on voluntary ethanol intake to the consumption of an appetitive rewarding substance (saccharin) or an aversive solution (quinine or denatonium). Whereas saccharin intake was similar in STEP knockout (KO) and wild type (WT) littermate mice, the consumption of ethanol as well as quinine and denatonium was increased in STEP KO mice. These results suggested that the aversive taste of these substances was masked upon deletion of the STEP gene. We therefore hypothesized that STEP contributes to the physiological avoidance towards aversive stimuli. To further test this hypothesis, we measured the responses of STEP KO and WT mice to lithium-induced conditioned place aversion (CPA) and found that whereas WT mice developed lithium place aversion, STEP KO mice did not. In contrast, conditioned place preference (CPP) to ethanol was similar in both genotypes. Together, our results indicate that STEP contributes, at least in part, to the protection against the ingestion of aversive agents.

The STriatal-Enriched protein tyrosine Phosphatase 61 (STEP61 ) inhibits the activity of the tyrosine kinase Fyn and dephosphorylates the GluN2B subunit of the NMDA receptor, whereas the protein kinase A phosphorylation of STEP61 inhibits the activity of the phosphatase (Pharmacol. Rev., 64, , p. 65). Previously, we found that ethanol activates Fyn in the dorsomedial striatum (DMS) leading to GluN2B phosphorylation, which, in turn, underlies the development of ethanol intake (J. Neurosci., 30, , p. 10187). Here, we tested the hypothesis that inhibition of STEP61 by ethanol is upstream of Fyn/GluN2B. We show that exposure of mice to ethanol increased STEP61 phosphorylation in the DMS, which was maintained after withdrawal and was not observed in other striatal regions. Specific knockdown of STEP61 in the DMS of mice enhanced ethanol-mediated Fyn activation and GluN2B phosphorylation, and increased ethanol intake without altering the level of water, saccharine, quinine consumption or spontaneous locomotor activity. Together, our data suggest that blockade of STEP61 activity in response to ethanol is sufficient for the activation of the Fyn/GluN2B pathway in the DMS. Being upstream of Fyn and GluN2B, inactive STEP61 in the DMS primes the induction of ethanol intake. We show that ethanol-mediated inhibition of STEP61 in the DMS leads to Fyn activation and GluN2B phosphorylation. (a) Under basal conditions, active STEP61 inhibits Fyn activity and dephosphorylates GluN2B. (b) Ethanol leads to the phosphorylation of STEP61 on a specific inhibitory site. The inhibition of STEP61 activity contributes to the activation of Fyn in response to ethanol, which, in turn, phosphorylates GluN2B. These molecular adaptations in the DMS promote ethanol drinking.

The molecular events that are responsible for strengthening synaptic connections and how these are linked to memory and learning are discussed. The laboratory preparations that allow the investigation of these events are also described.

The molecular activities which take place inside neurones during synaptic plasticity development are examined. The molecular events during memory consolidation and learning are investigated.

A research on how synaptic plasticity is abnormally regulated in fragile X syndrome and how this abnormality can be reversed by therapeutic interventions is presented. Fragile X syndrome is a disorder of synaptic plasticity that contributes to abnormal development and interferes with normal learning and memory.

Fragile X syndrome, the most common form of inherited mental retardation is discussed. The relationship between specific impairments in synaptic plasticity and Fragile X syndrome is investigated as it strengthens synaptic contacts between neurons.

A study presented on the effect of parenting on stress response and other behaviors show that animals exposed to a high degree of nurturing show a blunted response to stress. Molecular mechanisms responsible for these differences in the adult offspring as well as the molecular mechanisms by which epigenetic effects are propagated from one generation to the next are discussed.

The article highlights the field of epigenetics and its relevance in determining the effects of maternal nurturing on behavioral patterns in offsprings. Results concluded that maternal behavior influences the offspring's behavior to stress in adulthood and the effects are transgenerational through epigenetic mechanisms.

Objective: This is a review of progress made in the understanding of Tourette syndrome (TS) during the past decade including models of pathogenesis, state-of-the-art assessment techniques, and treatment. Method: Computerized literature searches were conducted under the key words "Tourette syndrome," "Tourette disorder," and "tics." Only references from 1996-2006 were included. Results: Studies have documented the natural history of TS and the finding that tics usually improve by the end of the second decade of life. It has also become clear that TS frequently co-occurs with attention-deficit/hyperactivity disorder), obsessive-compulsive disorder, and a range of other mood and anxiety disorders. These comorbid conditions are often the major source of impairment for the affected child. Advances have also been made in understanding the underlying neurobiology of TS using in vivo neuroimaging and neurophysiology techniques. Progress on the genetic front has been less rapid. Proper diagnosis and education (involving the affected child and his or her parents, teachers, and peers) are essential prerequisites to the successful management of children with TS. When necessary, modestly effective antitic medications are available, although intervening to treat the comorbid attention-deficit/hyperactivity disorder and/or obsessive-compulsive disorder is usually the place to start. Conclusions: Prospective longitudinal studies and randomized clinical trials have led to the refinement of several models of pathogenesis and advanced our evidence base regarding treatment options. However, fully explanatory models are needed that would allow for more accurate prognosis and the development of targeted and efficacious treatments. (Contains 1 table.)

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tins.2006.06.007 Byline: Steven P. Braithwaite (1), Surojit Paul (2), Angus C. Nairn (3), Paul J. Lombroso (4) Abstract: Striatal enriched tyrosine phosphatase (STEP) has recently been identified as a crucial player in the regulation of synaptic function. It is restricted to neurons within the CNS and acts by downregulating the activity of MAP kinases, the tyrosine kinase Fyn and NMDA receptors. By modulating these substrates, STEP acts on several parallel pathways that impact upon the progression of synaptic plasticity. Here, we review recent advances that demonstrate the importance of STEP in normal cognitive function, and its possible involvement in cognitive disorders such as Alzheimer's disease. Author Affiliation: (1) AGY Therapeutics Inc., 270 E. Grand Avenue, South San Francisco, CA 94080, USA (2) Department of Neurology, University of New Mexico, Albuquerque, NM 87131, USA (3) Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06520, USA (4) Child Study Center, Yale University School of Medicine, New Haven, CT 06520, USA