Maternal suboptimal selenium intake and low-level lead exposure affect offspring's microglial immune profile and its reactivity to a subsequent inflammatory hit.

Micronutrients such as selenium (Se) are essentials since prenatal life to support brain and cognitive development. Se deficiency, which affects up to 1 billion people worldwide, can interact with common adverse environmental challenges including (Pb), exacerbating their toxic effects. Exploiting our recently validated rat model of maternal Se restriction and developmental low Pb exposure, our aims were to investigate: (i) the early consequences of suboptimal Se intake and low-Pb exposure on neuroinflammation in neonates' whole brains; (ii) the potential priming effect of suboptimal Se and low-Pb exposure on offspring's glial reactivity to a further inflammatory hit. To these aims female rats were fed with suboptimal (0.04 mg/kg; Subopt) and optimal (0.15 mg/kg; Opt) Se dietary levels throughout pregnancy and lactation and exposed or not to environmentally relevant Pb dose in drinking water (12.5 µg/mL) since 4 weeks pre-mating. We found an overall higher basal expression of inflammatory markers in neonatal brains, as well as in purified microglia and organotypic hippocampal slice cultures, from the Subopt Se offspring. Subopt/Pb cultures were highly activated than Subopt cultures and showed a higher susceptibility to the inflammatory challenge lipopolysaccharide than cultures from the Opt groups. We demonstrate that even a mild Se deficiency and low-Pb exposure during brain development can influence the neuroinflammatory tone of microglia, exacerbate the toxic effects of Pb and prime microglial reactivity to subsequent inflammatory stimuli. These neuroinflammatory changes may be responsible, at least in part, for adverse neurodevelopmental outcomes.

A snapshot of gut microbiota data from murine models of Autism Spectrum Disorder: Still a blurred picture.

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by deficits in social communication and interaction and repetitive/stereotyped behaviors. In recent years, the role of microbiota-gut-brain axis in ASD pathogenesis received growing attention, appearing as an attractive therapeutic target. We provide a comprehensive overview of changes in microbiota composition in ASD murine models so far identified, and summarize the therapeutic approaches targeting the microbiota on ASD-like neurobehavioral profile. Although alterations in microbiota composition have been observed in both genetic and environmental murine models of ASD, a clear microbiota profile shared by different ASD murine models has not been identified. We documented substantial discrepancies among studies (often within the same model), likely due to several confounding factors (from sex and age of animals to housing conditions). Despite these limitations, ASD animal models (under standardized conditions) remain a useful tool to evaluate (i) the beneficial effects of manipulations of gut microbiota on behavioral abnormalities; (ii) underlying neurobiological mechanisms related to gut-brain axis; and (iii) to identify optimal time windows for therapeutic interventions.

Conspiracy mentality and health-related behaviour during the COVID-19 pandemic: a multiwave survey in Italy.

OBJECTIVES: This study aimed to (1) explore the changes in conspiracy mentality across the four waves of the COVID-19 pandemic; (2) assess the relationship between conspirative mentality and psychological/behavioural variables; (3) identify the predictors of conspirative mentality; and (4) explore the effect of conspirative mentality on COVID-19 protective behaviour. STUDY DESIGN: This was a multiwave survey. METHODS: A total of 10,013 Italian individuals, aged 18-70 years, were assessed across the four waves (from January to May 2021) through online survey. We collected information about the sociodemographic characteristics of participants, personal experiences of COVID-19 infection, trust, COVID-19 protective behaviours, COVID-19 risk perception, arousal, auto-efficacy, resilience and well-being. Conspiracy mentality was assessed with the Conspiracy Mentality Questionnaire. The statistical analyses included exploratory factorial analyses, Pearson correlations and multiple linear regressions. RESULTS: The conspiracy mentality score during the COVID-19 pandemic was medium-high (mean 59.0 on a 0-100 scale) and slightly increased from 58.2 to 59.9 across months, in parallel with a slight decrease in trust in health institutions and scientific informational sources. Individuals aged >35 years, poorly educated and particularly scared about their financial situation were at risk of showing higher levels of conspirative mentality. Higher levels of conspirative mentality were risk factors for low levels of COVID-19 protective behaviours. CONCLUSIONS: Clear and effective communication may improve trust in health institutions and informational sources, decrease conspirative theories and increase compliance with protective behaviour.

Altered responsiveness to pups in virgin female mice of the BTBR strain: Insights from pattern of c-Fos expression in brain regions involved in maternal behavior.

BTBR is an inbred mouse strain that displays several behavioral alterations resembling the core symptoms of Autism Spectrum Disorder, including deficit in sociability. In the present study, we investigated whether the pup-induced maternal behavior in virgin female mice, a naturally rewarding behavior, is impaired in this strain similarly to social interaction with adult conspecifics. We firstly assessed the maternal responsiveness towards newly born pups expressed by either virgin female mice of the BTBR strain or of the normo-social B6 strain. Next, we examined in both strains the expression of c-Fos as a marker of neuronal activity in selected brain areas involved in the regulation of maternal behavior in rodents including the olfactory bulb, the medial preoptic area and the paraventricular nucleus (PVN). We also examined the effects of pup presentation on oxytocinergic neurons of the PVN, the major brain site of synthesis of oxytocin, which has a pivotal role in facilitation of maternal response and social responsiveness in general. As a final step, we assessed the c-Fos expression pattern comparing the effect of exposure to pups with that induced by exposure to another social stimulus, focusing on other areas implicated in maternal responsiveness as well as in the affective component of social behavior such as pyriform cortex and central and basolateral amygdala. Our data showed that BTBR virgin females are less responsive to presentation of pups in comparison to B6, in parallel with lower activation of brain areas implicated in the maternal and social responsiveness.

Regenerative medicine in Huntington's disease: Strengths and weaknesses of preclinical studies.

Huntington's disease (HD) is an inherited neurodegenerative disorder, characterized by impairment in motor, cognitive and psychiatric domains. Currently, there is no specific therapy to act on the onset or progression of HD. The marked neuronal death observed in HD is a main argument in favour of stem cells (SCs) transplantation as a promising therapeutic perspective to replace the population of lost neurons and restore the functionality of the damaged circuitry. The availability of rodent models of HD encourages the investigation of the restorative potential of SCs transplantation longitudinally. However, the results of preclinical studies on SCs therapy in HD are so far largely inconsistent; this hampers the individuation of the more appropriate model and precludes the comparative analysis of transplant efficacy on behavioural end points. Thus, this review will describe the state of the art of in vivo research on SCs therapy in HD, analysing in a translational perspective the strengths and weaknesses of animal studies investigating the therapeutic potential of cell transplantation on HD progression.

Sex dimorphic behaviors as markers of neuroendocrine disruption by environmental chemicals: the case of chlorpyrifos.

The complexity of the neuroendocrine level of investigation requires the assessment of behavioral patterns that extend beyond the reproductive functions, which are age- and sex-specific in rodents, described by defined clusters of behavioral items regulated by genetic, hormonal, and epigenetic factors. The study of social behavior in laboratory rodents reveals sex-dimorphic effects of environmental chemicals that may be undetected either by a traditional neurotoxicological approach or referring to the classical definition of endocrine disrupting chemicals. Here we review data on the neurobehavioral effects of developmental exposure to the non-persistent organophosphorus insecticide chlorpyrifos, whose neurotoxic activity at low doses is currently a matter of concern for children's health. In mice exposed to chlorpyrifos in utero and/or in early development social/emotional responses are differently affected in the two sexes in parallel with sex-dependent interference on hypothalamic neuroendocrine pathways regulating social behaviors (vasopressin, oxytocin, and steroid regulated systems). Through the analysis of complex sex-dimorphic behavioral patterns we show that neurotoxic and endocrine disrupting activities of CPF overlap. This widely diffused organophosphorus pesticide might thus be considered as a neuroendocrine disruptor possibly representing a risk factor for sex-biased neurodevelopmental disorders in children.

Endocrine disrupters: a review of some sources, effects, and mechanisms of actions on behaviour and neuroendocrine systems.

Some environmental contaminants interact with hormones and may exert adverse consequences as a result of their actions as endocrine disrupting chemicals (EDCs). Exposure in people is typically a result of contamination of the food chain, inhalation of contaminated house dust or occupational exposure. EDCs include pesticides and herbicides (such as dichlorodiphenyl trichloroethane or its metabolites), methoxychlor, biocides, heat stabilisers and chemical catalysts (such as tributyltin), plastic contaminants (e.g. bisphenol A), pharmaceuticals (i.e. diethylstilbestrol; 17α-ethinylestradiol) or dietary components (such as phytoestrogens). The goal of this review is to address the sources, effects and actions of EDCs, with an emphasis on topics discussed at the International Congress on Steroids and the Nervous System. EDCs may alter reproductively-relevant or nonreproductive, sexually-dimorphic behaviours. In addition, EDCs may have significant effects on neurodevelopmental processes, influencing the morphology of sexually-dimorphic cerebral circuits. Exposure to EDCs is more dangerous if it occurs during specific 'critical periods' of life, such as intrauterine, perinatal, juvenile or puberty periods, when organisms are more sensitive to hormonal disruption, compared to other periods. However, exposure to EDCs in adulthood can also alter physiology. Several EDCs are xenoestrogens, which can alter serum lipid concentrations or metabolism enzymes that are necessary for converting cholesterol to steroid hormones. This can ultimately alter the production of oestradiol and/or other steroids. Finally, many EDCs may have actions via (or independent of) classic actions at cognate steroid receptors. EDCs may have effects through numerous other substrates, such as the aryl hydrocarbon receptor, the peroxisome proliferator-activated receptor and the retinoid X receptor, signal transduction pathways, calcium influx and/or neurotransmitter receptors. Thus, EDCs, from varied sources, may have organisational effects during development and/or activational effects in adulthood that influence sexually-dimorphic, reproductively-relevant processes or other functions, by mimicking, antagonising or altering steroidal actions.

Chlorpyrifos and neurodevelopmental effects: a literature review and expert elicitation on research and policy

Organophosphate pesticides are widely used on food crops grown in the EU. While they have been banned from indoor use in the US for a decade due to adverse health effects, they are still the most prevalent pesticides in the EU, with Chlorpyrifos (CPF) being the most commonly applied. It has been suggested CPF affects neurodevelopment even at levels below toxicity guidelines. Younger individuals may be more susceptible than adults due to biological factors and exposure settings.

Effects of the food contaminant semicarbazide following oral administration in juvenile Sprague-Dawley rats.

Semicarbazide (SEM) is an azodicarbonamide by-product present in glass jar packaged foods including babyfoods, in bleaching steps and flour treatment. Experimental data showed SEM acting as osteolathyrogen agent, but few toxicological data are available in susceptible life-stages. This study aimed to evaluate effects of SEM oral administration for 28 days at 0, 40, 75, 140 mg/kg bw day during the juvenile period in Sprague-Dawley rats. Histopatological examinations of: epiphyseal cartilage - potential target of SEM lathyrogen action - testes, ovary, uterus, thyroid, thymus, spleen, adrenals, representative of the main developing organs relevant to juvenile toxicity, and neurobehavioural tests in males, were performed. Mortality at high and mid dose levels and significantly decreased body weight gain were observed in males even at the lowest dose. Lack of mineralization in cartilage at all dose levels was present. Marked alterations of spontaneous motor and exploratory behaviours were evident even at 40 mg/kg. Histological alterations were observed in all tissues; thyroid and ovary effects were present also at 40 mg/kg. The present study indicate that the NOAEL in juvenile rats is lower than 40 mg/kg for SEM oral administration. SEM administration during juvenile period exerted pleiotropic effects and further studies are suggested to elucidate mechanisms.

Behavioral and electrophysiological effects of the adenosine A2A receptor antagonist SCH 58261 in R6/2 Huntington's disease mice.

The effect of chronic treatment with the selective adenosine A2A receptor antagonist SCH 58261 on the behavioral and electrophysiological alterations typical of R6/2 mice (a transgenic mouse model of Huntington's disease, HD), has been studied. Starting from 5 weeks of age, R6/2 and wild type (WT) mice were treated daily with SCH 58261 (0.01 mg/kg i.p.) for 7 days. In the following weeks, the ability of mice to perform in the rotarod, plus maze and open field tests were evaluated. In addition, with electrophysiological experiments in corticostriatal slices we tested whether the well-known increased NMDA vulnerability of R6/2 mice was prevented by SCH 58261 treatment. We found that chronic treatment with SCH 58262: i) fully prevented the alterations in emotional/anxious responses displayed by R6/2 mice; ii) did not prevent the impairment in motor coordination; iii) abolished the increase in NMDA-induced toxicity observed in the striatum of HD mice. On balance, targeting A2A receptors seems to have some beneficial effects in HD even though, given the complexity of A2A receptor pharmacology and HD pathogenesis, further studies are necessary to clarify whether A2A receptor antagonists have therapeutic potential in HD.

The cannabinoid receptor agonist WIN 55,212-2 attenuates the effects induced by quinolinic acid in the rat striatum.

The ability of CB(1) receptors to regulate the release of glutamate in the striatum, together with the finding that, in experimental models of Huntington disease (HD), both endocannabinoid levels and CB(1) receptor densities are reduced, has prompted the investigation on the neuroprotective role of the cannabinoids in HD. Quinolinic acid (QA) is an excitotoxin that, when injected in the rat striatum reproduces many features of HD and that acts by stimulating glutamate outflow. The aim of the present study was to test the ability of the cannabinoid receptor agonist WIN 55,212-2 to prevent the effects induced by QA in the rat striatum. In microdialysis experiments, probe perfusion with WIN 55,212-2 significantly and dose-dependently prevented the increase in extracellular glutamate induced by QA. In electrophysiological recordings in corticostriatal slices, the application of WIN 55,212-2 prevented QA-induced reduction of the field potential amplitude. Both effects of WIN 55,212-2 were prevented by the CB(1) receptor antagonist AM 251. In in vivo experiments, intrastriatal WIN 55,212-2 significantly attenuated the striatal damage induced by QA, although no significant effects were observed on a behavioural ground. These data demonstrate that the stimulation of CB(1) receptors might lead to neuroprotective effects against excitotoxic striatal toxicity.

Nerve growth factor plasma levels and ventricular repolarization in Rett syndrome.

Rett syndrome is a severe neurological developmental disorder. In this syndrome, the high incidence of sudden death is correlated with an alteration of ventricular repolarization. The purpose of this study was to evaluate plasmatic levels of nerve growth factor (NGF) in Rett patients with prolonged corrected QT (QTc) interval in comparison with those of Rett patients with normal QTc. We observed 23 female Rett patients (9.9+/-4.7 years). NGF plasma levels and QTc interval were measured in all patients. Student t-test was performed for statistical analysis. NGF plasma levels were significantly lower in Rett patients with QTc interval prolongation (QTc > 0.44 sec) in comparison with Rett patients with a normal QTc interval (4.5+/-4.5 vs 11+/-8.3 pg/ml, p = 0.02). The alteration of NGF levels, observed in Rett patients with a long QTc interval, may explain the presence of an altered ventricular repolarization associated with a higher risk of cardiac arrhythmias.

Neonatal cholinergic lesions and development of exploration upon administration of the GABAa receptor agonist muscimol in preweaning rats.

Neonatal rats were administered 192 IgG-saporin (192 IgG-Sap), a selective cholinergic immunotoxin, on postnatal day (PND) 7. Behavioural responsiveness to muscimol, a GABAa receptor agonist, was then assessed using locomotor activity and object exploration tests on PND 18. In Experiment 1, 192 IgG-Sap-lesioned and control rats were injected with the GABAa agonist, muscimol, on PND 18 and tested in a standard open field test. Muscimol reduced rearing responses in both control and 192 IgG-Sap-lesioned animals whereas reduced wall-rearing responses occurred in control animals only. 192 IgG-Sap also reduced rearing and wall-rearing responses. In Experiment 2, muscimol effects were evaluated on PND 18 in a spatial open field test in which object exploration in addition to locomotion and rearing responses was assessed. Neonatal cholinergic lesion per se increased locomotion during object exploration while decreasing time spent exploring objects. Depressant effects of muscimol on object exploration were also evident. As a whole, these data provide evidence for (i) basal forebrain (BF) cholinergic control on locomotor activity and object exploration and (ii) GABAa-mediated regulation of selective behavioural patterns associated with locomotion and exploration in weaning rats. Neonatal cholinergic lesions, however, do not appear to alter reactivity to GABAergic agonists in juvenile rats.

Delayed developmental effects following prenatal exposure to drugs.

Increasing evidence points to the possible risks of delayed effects upon prenatal exposure to chemicals; the evaluation of such effects may pose serious problems to clinicians, epidemiologists and toxicologists. In fact, several systems (e.g., nervous, excretory) show important developmental processes well after the organogenetic period, up to the postnatal phase; accordingly, these are also expected to be sensitive targets of developmental toxicants, resulting in impairment of the function and/or functional reserve. This review describes the effects of several groups of drugs on the functional maturation and histogenesis of the kidney (e.g., aminoglycosides, angiotensin-converting enzyme inhibitors, indomethacin) and brain (e.g., anticonvulsivants, antiretroviral compounds, benzodiazepines) upon exposure in utero of humans and laboratory animals. The available data stress the importance for risk assessment of an adequate knowledge of both developmental biology and mechanisms of toxicity. The design of developmental toxicity studies should allow an evaluation of targets most relevant for a given drug (or group of drugs); moreover, the analysis of functional development should receive the due attention within the safety assessment of chemicals.

Prenatal exposure to anti-HIV drugs: neurobehavioral effects of zidovudine (AZT) + lamivudine (3TC) treatment in mice.

BACKGROUND: The new antiretroviral treatments that combine the zidovudine (AZT) regimen with lamivudine (3TC) appear as a cost-effective alternative to the current AZT monotherapy to prevent mother-to-fetus transmission of the HIV-1 virus. Recent evidence in uninfected children raised concern about the long-term effects of perinatal exposure to AZT and 3TC, especially when used in combination. Animal studies indicated behavioral changes in offspring exposed perinatally to both AZT and 3TC, whereas no animal data are available on the effects of the perinatal exposure to the AZT + 3TC combination on neurodevelopment. METHODS: Pregnant CD-1 mice received p.o. AZT + 3TC (160 and 500 mg/kg, respectively) or vehicle solution (NaCl 0.9%) twice daily from gestational day 10 to delivery. Maternal reproductive endpoints such as pregnancy length, abortion, litter size, sex ratio, and offspring viability were assessed. Pups were scored for different somatic and behavioral endpoints, including sensorimotor development, homing performance on postnatal day (PND) 10, passive-avoidance testing (PND 22-23), locomotor activity (PND 23), and social interaction (PND 35). RESULTS: While no effects were observed on maternal reproductive endpoints, treated pups showed a long-lasting reduction of body weight and a slightly delayed maturation of placing and grasping reflexes and pole grasping. No effects on passive-avoidance or locomotor activity were found. AZT + 3TC-treated mice showed selective alterations in the social interaction test; the treated female offspring also displayed a significant reduction of affiliative interactions. CONCLUSIONS: The combination of AZT and 3TC (1) induced small, but more marked, effects on somatic and sensorimotor development than either of these drugs administered separately; and (2) affected juvenile social behavior.

[Animal models of hypoxic-ischemic encephalopathy]. / I modelli animali di encefalopatia ipossico-ischemica.

This review presents the animal models more widely used to study neurological and neuropathological outcomes of perinatal asphyxia. Methods used to induce hypoxia/ischemia in fetal and newborn non-human primates, lambs, piglets and rodents are concisely described, reporting the more relevant neuropathological and behavioural findings. In line with human observational data, experimental studies indicate that motor behaviour and attentional/cognitive abilities are among those behavioural regulations more significantly affected by perinatal asphyxia.

Developmental profile of serum nerve growth factor levels in Rett complex.

Rett syndrome (RS) is a progressive neurodevelopmental disorder predominant in females, characterised by mental deficiency, stereotyped hand-washing and apraxia. Notwithstanding the recent identification of the MECP2 gene likely involved in the pathogenesis of SR, the neurobiological bases of this syndrome are still largely unknown. Converging evidence shows that the brain levels of nerve growth factor (NGF), a neurotrophin regulating the development and functioning of central cholinergic neurons, are decreased in RS girls. In this study, the serum levels of NGF were measured in classic RS, in the preserved speech variant (PSV) and in normal controls. Overall analysis failed to evidence significant differences among the three groups. However, whereas NGF levels increased significantly with age in controls, the opposite profile was observed in classic RS, with a progressive age-dependent decrease of NGF. In PSV subjects NGF levels remained constant with age. These findings strengthen the hypothesis of NGF involvement in the pathogenesis of RS.

Serum NGF levels in children and adolescents with either Williams syndrome or Down syndrome.

The neurotrophin nerve growth factor (NGF) is a major regulator of peripheral and central nervous system development. Serum NGF was measured in normally developing control children (n=26) and in individuals affected by congenital syndromes associated with learning disability: either Williams syndrome (WS; n=12) or Down syndrome (DS; n=21). Participants were assessed at three distinct developmental stages: early childhood (2 to 6 years), childhood (8 to 12 years), and adolescence (14 to 20 years). A sample was taken only once from each individual. Serum NGF levels were markedly higher in participants with WS, than DS and control participants. In addition, different developmental profiles emerged in the three groups: while in normally developing individuals NGF levels were higher in early childhood than later on, children with WS showed constantly elevated NGF levels. When compared to control participants, those with DS showed lower NGF levels only during early childhood. Neuropsychological assessment confirmed previously reported differences among the three groups in the development of linguistic/cognitive abilities. Some features of individuals with WS, such as hyperacusis and hypertension, could be related to high-circulating NGF levels.

Prolonged perinatal exposure to AZT affects aggressive behaviour of adult CD-1 mice.

RATIONALE: AZT is commonly administered to seropositive women and their neonates to prevent mother-to-child transmission of HIV. Recently, animal studies performed in monkeys and rodents have revealed that pre- and/or perinatal exposure to AZT induces age- and sex-dependent behavioural alterations in the offspring, possibly resulting from an action of this drug on CNS targets. Long-term effects of prenatal AZT treatment on social/aggressive behaviour of adult male mice have been previously described. Specifically, AZT has been shown to induce selective changes in the offensive components of agonistic interactions. OBJECTIVE: The aim of the present study was to extend previous findings, analysing the long-term effects of a more prolonged AZT exposure on intraspecific male mice agonistic behaviour. METHODS: AZT was given orally twice daily to pregnant CD- mice. The dosage selected for AZT was 160 mg/kg. Saline solution (0.9% NaCl) was used as vehicle. Starting on postnatal day (PND) 60 isolated males underwent five 15-min repeated encounters with an opponent of the same age and strain isolated for the same amount of time. Furthermore, a locomotor activity test (PND 67) and a hot-plate test (52 +/- 0.1 degrees C) (PND 74) were performed to assess AZT effects on, respectively, general activity and pain sensitivity. RESULTS: AZT perinatal exposure reduced attack behaviour of adult mice, while increasing the likelihood of them behaving as subordinates. Furthermore, long-term effects of AZT treatment on pain sensitivity were found in the hot-plate test, with AZT mice showing higher pain thresholds than controls. CONCLUSIONS: Overall, these data indicate that perinatal exposure to drugs such as AZT exerts selective effects on the developing CNS, resulting in long-term behavioural disturbances. Future studies will need to address the issue of the specific mechanisms underlying these effects.

Ontogeny of spatial discrimination in mice: a longitudinal analysis in the modified open-field with objects.

The present longitudinal study investigated the emergence of spatial discrimination and reaction to novelty in CD-1 mice, using a modified open-field test with four objects, a test in which responses to both spatial rearrangement of familiar objects and object novelty are assessed. Male and female mice were tested on postnatal days (pnd) 18, 28, 46 and 90. Locomotor activity was highest on pnd 90, whereas time spent on objects before rearrangement was highest on pnd 46. Eighteen-day old mice were unable to detect both object rearrangement and object novelty, suggesting immaturity in processing spatial information. On days 28 and 46 mice showed a clear response to object novelty, actively exploring the unfamiliar object placed in the arena, while at these ages object displacement elicited a generalized increase of exploration, not directed towards the displaced objects. A clear and selective response to object displacement emerged only at adulthood (day 90).