Taurine Increases Zinc Preconditioning-Induced Prevention of Nitrosative Stress, Metabolic Alterations, and Motor Deficits in Young Rats following Intrauterine Ischemia

Oxygen deprivation in newborns leads to hypoxic-ischemic encephalopathy, whose hallmarks are oxidative/nitrosative stress, energetic metabolism alterations, nutrient deficiency, and motor behavior disability. Zinc and taurine are known to protect against hypoxic-ischemic brain damage in adults and neonates. However, the combined effect of prophylactic zinc administration and therapeutic taurine treatment on intrauterine ischemia- (IUI-) induced cerebral damage remains unknown. The present work evaluated this issue in male pups subjected to transient IUI (10 min) at E17 and whose mothers received zinc from E1 to E16 and taurine from E17 to postnatal day 15 (PND15) via drinking water. We assessed motor alterations, nitrosative stress, lipid peroxidation, and the antioxidant system comprised of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Enzymes of neuronal energetic pathways, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), were also evaluated. The hierarchization score of the protective effect of pharmacological strategies (HSPEPS) was used to select the most effective treatment. Compared with the IUI group, zinc, alone or combined with taurine, improved motor behavior and reduced nitrosative stress by increasing SOD, CAT, and GPx activities and decreasing the GSSG/GSH ratio in the cerebral cortex and hippocampus. Taurine alone increased the AST/ALT, LDH/ALT, and AST/LDH ratios in the cerebral cortex, showing improvement of the neural bioenergetics system. This result suggests that taurine improves pyruvate, lactate, and glutamate metabolism, thus decreasing IUI-caused cerebral damage and relieving motor behavior impairment. Our results showed that taurine alone or in combination with zinc provides neuroprotection in the IUI rat model.

Morphofunctional Alterations of the Hypothalamus and Social Behavior in Autism Spectrum Disorders

An accumulating body of evidence indicates a tight relationship between the endocrine system and abnormal social behavior. Two evolutionarily conserved hypothalamic peptides, oxytocin and arginine-vasopressin, because of their extensively documented function in supporting and regulating affiliative and socio-emotional responses, have attracted great interest for their critical implications for autism spectrum disorders (ASD). A large number of controlled trials demonstrated that exogenous oxytocin or arginine-vasopressin administration can mitigate social behavior impairment in ASD. Furthermore, there exists long-standing evidence of severe socioemotional dysfunctions after hypothalamic lesions in animals and humans. However, despite the major role of the hypothalamus for the synthesis and release of oxytocin and vasopressin, and the evident hypothalamic implication in affiliative behavior in animals and humans, a rather small number of neuroimaging studies showed an association between this region and socioemotional responses in ASD. This review aims to provide a critical synthesis of evidences linking alterations of the hypothalamus with impaired social cognition and behavior in ASD by integrating results of both anatomical and functional studies in individuals with ASD as well as in healthy carriers of oxytocin receptor (OXTR) genetic risk variant for ASD. Current findings, although limited, indicate that morphofunctional anomalies are implicated in the pathophysiology of ASD and call for further investigations aiming to elucidate anatomical and functional properties of hypothalamic nuclei underlying atypical socioemotional behavior in ASD.

Low (Therapeutic) Dose of Warfarin Is Not Associated with Cognitive and Exploratory Behavior Impairment in Rats: Mechanistic Studies (OR15-01-19)

Objectives In addition to its role in hemostasis, vitamin K (VK) is involved in brain function through various proteins and sphingolipid metabolism. Warfarin (W), a widely prescribed anticoagulant drug, exerts its beneficial effect in coagulation by partially blocking the recycling of the vitamin. In previous studies, we provided evidence that, when administered in large doses, W leads to cognitive and exploratory behavior impairment, and alteration in the VK dependent proteins Gas6 and protein S (PS) and their downstream pro-survival extracellular signal-regulated (ERK) and serine-threonine (Akt) kinases pathways. In light of its widespread use as oral anticoagulant, the present study aimed to investigate the impact of W on cognition and behavior, Gas6 and PS and their signaling pathways when administered in doses comparable to those used in the clinical setting. Methods Male Wistar rats (n = 14/gp) were fed an AIN-93 based diet containing 750 mcg phylloquinone/kg/d and were randomly allocated to treatment with 0,1 mg W/kg/d (in drinking water) (W group) or not (C group), for 9 wks. Spatial memory (Morris Water Maze) and exploratory behavior (Open Field) were assessed. Gas6, PS, pAkt, pERK, caspases −3 and −12 (apoptosis), brain-derived neurotrophic factor (BDNF), and microglial CD11b/c protein (a marker of inflammation), were assessed by immunoblotting in hippocampus (HPP), frontal cortex (FC), and striatum (STR), three regions involved in cognition. VK contents were determined in these 3 brain regions by HPLC. Group difference was tested by unpaired Student t-test. Results Low dose W had no impact on brain VK concentrations, spatial memory, and exploratory behavior (all P > 0.05). In contrast, W treatment was associated with numerous cell-signaling modulations, namely increased PS, ERK and Akt activity, and caspase −3 and −12 expression, in HPP; increased BDNF in FC and STR; increased expression of CD11bc in STR, (all P < 0.05). Conclusions This study provides evidence that low dose W is not associated with cognitive and behavioral impairment despite numerous cell-signaling modulations that have the potential to be beneficial or detrimental to the brain. Whether these events represent compensatory mechanisms to maintain homeostasis deserves further investigation. Funding Sources Study funded by CIHR.

Arid1b haploinsufficient mice reveal neuropsychiatric phenotypes and reversible causes of growth impairment

Sequencing studies have implicated haploinsufficiency of ARID1B, a SWI/SNF chromatin-remodeling subunit, in short stature (Yu et al., 2015), autism spectrum disorder (O'Roak et al., 2012), intellectual disability (Deciphering Developmental Disorders Study, 2015), and corpus callosum agenesis (Halgren et al., 2012). In addition, ARID1B is the most common cause of Coffin-Siris syndrome, a developmental delay syndrome characterized by some of the above abnormalities (Santen et al., 2012; Tsurusaki et al., 2012; Wieczorek et al., 2013). We generated Arid1b heterozygous mice, which showed social behavior impairment, altered vocalization, anxiety-like behavior, neuroanatomical abnormalities, and growth impairment. In the brain, Arid1b haploinsufficiency resulted in changes in the expression of SWI/SNF-regulated genes implicated in neuropsychiatric disorders. A focus on reversible mechanisms identified Insulin-like growth factor (IGF1) deficiency with inadequate compensation by Growth hormone-releasing hormone (GHRH) and Growth hormone (GH), underappreciated findings in ARID1B patients. Therapeutically, GH supplementation was able to correct growth retardation and muscle weakness. This model functionally validates the involvement of ARID1B in human disorders, and allows mechanistic dissection of neurodevelopmental diseases linked to chromatin-remodeling.