Role of wnt signaling in the control of adult hippocampal functioning in health and disease: therapeutic implications.

It is well recognized the role of the Wnt pathway in many developmental processes such as neuronal maturation, migration, neuronal connectivity and synaptic formation. Growing evidence is also demonstrating its function in the mature brain where is associated with modulation of axonal remodeling, dendrite outgrowth, synaptic activity, neurogenesis and behavioral plasticity. Proteins involved in Wnt signaling have been found expressed in the adult hippocampus suggesting that Wnt pathway plays a role in the hippocampal function through life. Indeed, Wnt ligands act locally to regulate neurogenesis, neuronal cell shape and pre- and postsynaptic assembly, events that are thought to underlie changes in synaptic function associated with long-term potentiation and with cognitive tasks such as learning and memory. Recent data have demonstrated the increased expression of the Wnt antagonist Dickkopf-1 (DKK1) in brains of Alzheimer´s disease (AD) patients suggesting that dysfunction of Wnt signaling could also contribute to AD pathology. We review here evidence of Wnt-associated molecules expression linked to physiological and pathological hippocampal functioning in the adult brain. The basic aspects of Wnt related mechanisms underlying hippocampal plasticity as well as evidence of how hippocampal dysfunction may rely on Wnt dysregulation is analyzed. This information would provide some clues about the possible therapeutic targets for developing treatments for neurodegenerative diseases associated with aberrant brain plasticity.

Diagnostic Performance of AST Scale in Mexican Male Population for Alcohol Withdrawal Syndrome.

Alcohol withdrawal syndrome (AWS) represents an adverse consequence of chronic alcohol use that may lead to serious complications. Therefore, AWS requires timely attention based on its early recognition, where easy-to-apply diagnostic tools are desirable. Our aim was to characterize the performance of a short-scale AST (Anxiety, Sweats, Tremors) in patients from public general hospitals. We conducted a cross-sectional study of patients attended at the Emergency Department diagnosed with AWS. Three scales were applied: CIWA-Ar (Clinical Institute Retirement Assessment Scale-Revised), GMAWS (Glasgow Modified Alcohol Withdrawal Syndrome) and AST. Cronbach's alpha and Cohen's kappa tests were used for reliability and concordance. Factorial analysis and diagnostic performance including ROC curve were carried out. Sixty-eight males with a mean age of 41.2 years old, with high school education and robust alcohol consumption, were included. Mean scores for CIWA-Ar, GMWAS and AST were 17.4 ± 11.2, 3.9 ± 2.3 and 3.8 ± 2.6, respectively, without significant differences. The AST scale showed an acceptable reliability and concordance (0.852 and 0.439; p < 0.0001) compared with CIWA-Ar and GMAWS. AST component analysis evidenced tremor (77.5% variance), sweat (12.1% variance) and anxiety (10.4% variance). Diagnostic performance of the AST scale was similar to the GMAWS scale, evidencing a sensitivity of 84%, specificity of 83.3% and Area Under the Curve (AUC) of 0.837 to discriminate severe AWS, according to CIWA-Ar. The performance of the AST scale to evaluate AWS is comparable with the commonly used CIWA-Ar and GMAWS scales. AST further represents an easy-to-apply instrument.

Differential Changes in the Number and Morphology of the New Neurons after Chronic Infusion of Wnt7a, Wnt5a, and Dkk-1 in the Adult Hippocampus In Vivo.

In the adult hippocampus of many mammals, a particular microenvironment in the neurogenic niche regulates the proliferation, self-renewal, and differentiation of neuronal stem cells. In this proliferative niche, a variety of molecules provide a finely regulated molecular signaling that controls stem cell properties. During development, Wnt signaling has been implicated in cell fate determination and proliferation, in the establishment of cell polarity, as well as a cue for axonal growth and dendrite orientation. In the adult brain, this pathway also participates in the stem cell self-renewal and neuronal differentiation. However, the effects of the chronic Wnt signaling modulation in the adult hippocampus, through the infusion of Wnt7a, Wnt5a, and Dkk-1, on the rate of neurogenesis and on the induction of neurite arborization have not been studied. In this study, we show that Wnt7a and Wn5a further increased the rate of newly generated neurons. However, Wnt5a exerted additional effects by promoting neurite growth and neurite misorientation in the dentate gyrus of adult rats. The chronic exposure to Dkk-1 also generated aberrant location of growing neurites. These results suggest that the interplay of canonical and non-canonical Wnt ligands participates in neuronal stem cell proliferation and in the establishment of proper neurite maturation. Anat Rec, 302:1647-1657, 2019. © 2019 American Association for Anatomy.

Chronic infusion of Wnt7a, Wnt5a and Dkk-1 in the adult hippocampus induces structural synaptic changes and modifies anxiety and memory performance.

Wnt signaling plays an important role in the adult brain function and its dysregulation has been implicated in some neurodegenerative pathways. Despite the functional role of the Wnt signaling in adult neural circuits, there is currently no evidence regarding the relationships between exogenously Wnt signaling activation or inhibition and hippocampal structural changes in vivo. Thus, we analyzed the effect of the chronic infusion of Wnt agonists, Wnt7a and Wnt5a, and antagonist, Dkk-1, on different markers of plasticity such as neuronal MAP-2, Tau, synapse number and morphology, and behavioral changes. We observed that Wnt7a and Wnt5a increased the number of perforated synapses and the content of pre-and postsynaptic proteins associated with synapse assembly compared to control and Dkk-1 infusion. These two Wnt agonists also reduced anxiety-like behavior. Conversely, the canonical antagonist, Dkk-1, increased anxiety and inhibited spatial memory recall. Therefore, the present study elucidates the potential participation of Wnt signaling in the remodeling of hippocampal circuits underlying plasticity events in vivo, and provides evidence of the potential benefits of Wnt agonist infusion for the treatment of some neurodegenerative conditions.

GSK3 Function in the Brain during Development, Neuronal Plasticity, and Neurodegeneration.

GSK3 has diverse functions, including an important role in brain pathology. In this paper, we address the primary functions of GSK3 in development and neuroplasticity, which appear to be interrelated and to mediate age-associated neurological diseases. Specifically, GSK3 plays a pivotal role in controlling neuronal progenitor proliferation and establishment of neuronal polarity during development, and the upstream and downstream signals modulating neuronal GSK3 function affect cytoskeletal reorganization and neuroplasticity throughout the lifespan. Modulation of GSK3 in brain areas subserving cognitive function has become a major focus for treating neuropsychiatric and neurodegenerative diseases. As a crucial node that mediates a variety of neuronal processes, GSK3 is proposed to be a therapeutic target for restoration of synaptic functioning and cognition, particularly in Alzheimer's disease.