Flavia Chiarotti

Risk taking during exploration of a plus-maze is greater in adolescent than in juvenile or adult mice

Abstract We investigated age-related changes in exploratory drive and anxiety in a plus-maze paradigm. We observed the behaviour of outbred CD-1 mice, Mus musculus , of both sexes at three ages: juvenile (35 days), adolescent (48 days) and adult (61 days). Juvenile and adult mice strongly avoided the open arms of the apparatus, suggesting high levels of anxiety. In contrast, adolescents spent similar amounts of time in both open and closed arms. They also entered the open arms more quickly and more often than the other age groups. No age-related differences were found in the frequency of the stretched-attend posture, a behavioural pattern considered to indicate risk assessment. The data can be interpreted in terms of either an increased exploratory drive or reduced environment-related anxiety, or both, during the adolescent period. This is consistent with previous evidence of elevated levels of novelty seeking and reduced behavioural and physiological responses to stressful situations in mice and rats around this age. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .

Long-term effects of the periadolescent environment on exploratory activity and aggressive behaviour in mice: social versus physical enrichment

The aims of the present study were (i) to investigate the effects of environmental enrichment during periadolescence on different behavioural and neurochemical responses in male CD-1 mice at adulthood and (ii) to describe the relative role of the physical and social components of the enrichment in producing these effects. Thirty 5-day-old mice were randomly assigned to one of the following housing conditions lasting five consecutive days: (i) individually housed in a standard cage, (ii) housed in pairs in a standard cage, (iii) individually housed in a physically enriched cage, and (iv) housed in pairs in a physically enriched cage. At adulthood, 80 days after the enrichment exposure, the explorative behaviour in an open field, as well as the behaviour in agonistic encounters, was evaluated in association with the analysis of selected central (hypothalamic levels of nerve growth factor (NGF) and brain-derived growth factor(BDNF)) and peripheral (plasma corticosterone levels) biochemical parameters. The results show that the long-term effects of the physical and the social enrichment are different and not additive. In particular, while social enrichment by itself exerted very limited effects, physical enrichment decreased the exploratory activity and altered social behaviour. Mice housed in pairs in an enriched cage showed low activity levels in the open field, and they tended to become more frequently dominant, although showing a more affiliative and less aggressive social interaction strategy. Furthermore, they presented low levels of hypothalamic NGF and high levels of brain-derived growth factor, suggesting an important effect of the combination of social and physical enrichment on neurobehavioral markers of brain plasticity and on animal ability to cope with social challenges.

Patent Foramen Ovale and Transcranial Doppler: Comparison of Different Procedures

BACKGROUND AND PURPOSE The capability of transcranial Doppler sonography (TCD) to detect a patent foramen ovale (PFO) has been established. However, which provocative maneuver and what timing of contrast injection are most effective to induce a right-to-left shunt has not yet been determined. METHODS We selected 38 cerebrovascular patients (21 men, 17 women) with positive contrast study for PFO on transesophageal echocardiography. Patients underwent a TCD with bilateral monitoring of the middle cerebral arteries (MCAs) and injection of a contrast solution. The injection was repeated (1) during normal breathing (basal conditions); (2) before Valsalva maneuver (VM); (3) during VM; (4) immediately after VM; and (5) during cough. The latency time and the total number of microbubbles for each side were recorded. RESULTS TCD found positive results for PFO in 30 patients. Twenty were positive even during basal conditions. The number of positive cases varied according to the timing of the VM in relation to the contrast injection: 28, 25, and 27 cases were positive when the injection was performed before, during, and after VM, respectively, while 26 were positive during cough. There were significant differences in the number of microbubbles in the MCAs between the procedures (P < .001, ANOVA): the highest number was detected in the injection before VM and the lowest number during basal conditions (P < .001, Wilcoxons test with Bonferronis correction). The latency time was significantly shorter when the injection followed VM. CONCLUSIONS The injection performed before VM appeared to be the most effective TCD procedure in determining the transit of microbubbles through a PFO and subsequently in the MCAs.

Maternal separation and maternal care act independently on the development of HPA responses in male rats

Postnatal manipulations such as brief (early handling, EH) and long, daily mother-offspring separations (maternal separation, MS) in rats are used to study the mechanisms underlying developmental plasticity of stress and fear responses, and to model stress-related disorders in humans and in non-human animals. Current evidence suggests that, compared to non-handled rats, EH reduces hypothalamic-pituitary-adrenal (HPA) reactivity in the adult offspring through stimulating increased levels of active maternal care. In contrast, despite a similar increase in active maternal care, MS does not reduce HPA reactivity, thus suggesting that long mother-offspring separations may counteract the effects of increased active maternal care. We therefore attempted to selectively manipulate levels of active maternal care and durations of mother-offspring separations in neonate rats. Rat pups were exposed to different combinations of EH and MS from postnatal day (PND) 2 to 10 using a split-litter design. Maternal behaviour was recorded from PND 2 to 8 and behavioural and endocrine responses to stress were studied in adult male offspring. Low levels of maternal care combined with long mother-offspring separations increased HPA-reactivity compared to both high maternal care combined with long mother-offspring separations and low maternal care combined with brief separations. These findings further support the hypothesis that active maternal care and long mother-offspring separation act independently, and exert opposing effects, on adult offsprings HPA responses, but that increased maternal care may buffer the adverse consequences of long separations.

The pathogenesis of the white matter abnormalities in phenylketonuria. A multimodal 3.0 tesla MRI and magnetic resonance spectroscopy (1H MRS) study

Objective: To gain insights into the nature and pathogenesis of white matter (WM) abnormalities in PKU. Methods: Thirty-two patients with phenylalanine hydroxylase deficiency (21 with early and 11 with late diagnosis and treatment) and 30 healthy controls underwent an integrated clinical, neuroimaging (3.0 T MRI, diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI)) and neurochemical (1H MRS) investigation. Results: All patients had white matter abnormalities on T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR) scans; parietal white was consistently affected, followed by occipital, frontal and temporal white matter. T1-weighted hypointense alterations were also found in 8 of 32 patients. DWI hyperintense areas overlapped with those detected on T2W/FLAIR. The apparent diffusion coefficient (ADC) was reduced and correlated inversely with severity of white matter involvement. Fractional anisotropy index, eigenvalues λmin, λmiddle, λmax obtained from DTI data, and the principal brain metabolites assessed by 1H MRS (except brain phenylalanine (Phe)) were normal. Brain Phe peak was detected in all but two subjects. Brain and blood Phe were strictly associated. Blood Phe at the diagnosis, patient’s age, and concurrent brain Phe independently influence white matter alteration (as expressed by conventional MRI or ADC values). Conclusions: (a) MRI abnormalities in phenylketonuria are the result of a distinctive alteration of white matter suggesting the intracellular accumulation of a hydrophilic metabolite, which leaves unaffected white matter architecture and structure. (b) White matter abnormalities do not seem to reflect the mechanisms involved in the derangement of mental development in PKU. (c) Our data do not support the usefulness of conventional brain MRI examination in the clinical monitoring of phenylketonuria patients.

Problems of test choice and data analysis in behavioral teratology: The case of prenatal benzodiazepines

Higher-tier tests for the assessment of early treatment effects should be aimed at providing specific information on the behavior processes affected, rather than simply at extending the descriptive data base. The contrast between positive and negative results can be useful to point out possible mechanisms of action. For example, late prenatal oxazepam exposure of mice produced a reduction of the amphetamine hyperactivity at the end of the second postnatal week, but did not significantly affect the response to scopolamine at the end of the third week. An impairment of active locomotor avoidance was observed at the young adult stage, which contrasted with the absence or scarcity of changes in passive avoidance and extinction responding in the same go-no go tests. These changes in response-activating mechanisms appear to be in agreement with the medium- and long-term effects on CNS monoamine metabolism described in the literature. As concerns statistical analysis, dichotomous or polytomous data obtained, e.g., by the Fox battery are not yet amenable to an adequate processing, due to the shortcomings of the available nonparametric tests. By contrast, mixed-model ANOVAs can cope with complex data obtained, e.g., in activity and learning tests. However, the available checks on various assumptions (normality, homogeneity of variance, sphericity) are not valid when nested factors, block factors and repeated measures coexist. Finally, the more usual cross-fostering procedures provide adequate information on some aspects (e.g., separation of main effects of prenatal treatments from postnatal maternal effects) but not on others.(ABSTRACT TRUNCATED AT 250 WORDS)

DEVELOPMENTAL EXPOSURE TO CHLORPYRIFOS INDUCES ALTERATIONS IN THYROID AND THYROID HORMONE LEVELS WITHOUT OTHER TOXICITY SIGNS IN CD1 MICE

Organophosphorus insecticides, as Chlorpyrifos (CPF), are widely used in agriculture and against household pests; these compounds receive an increasing consideration as potential endocrine disrupters. The aim of the present study was to examine the potential short- and long-term effects of CPF on thyroid and adrenal glands in CD1 mice following exposure at dose levels not inducing brain acetyl cholinesterase (AchE) inhibition, during gestational and/or postnatal vulnerable phases. Pregnant dams were treated with 0, 3, 6 mg/kg bw/day of CPF on gestational days 15-18. After delivery, pups were treated subcutaneously on postnatal days (PND) 11-14 with: 0, 1, 3 mg/kg bw/day of CPF. Serum thyroxin (T4), thyroid and adrenals histology and histomorphometry were evaluated in dams and in F1 mice. In dams at 6 mg/kg, decreased T4 levels and increased cell height in thyroid were observed, and adrenal histology showed a slightly increased vacuolization in the X-zone. In the F1, short-term morphological modifications (reduced follicular size at PND 2) and long-term morphological (increased necrotic follicular cells) and biochemical alterations (reduced serum T4 levels) were found at PND 150 with an apparent higher vulnerability of males. For the first time these results indicate that CPF exposure at dose levels not inducing brain AchE inhibition causes thyroid alterations in dams and in F1 CD1 mice. Thyroid may be a sensitive target to CPF developmental exposure possibly leading to long-term effects on thyroid function. Because thyroid plays a pivotal role in mammalian development, these findings can be relevant to humans.

Spatial memory deficits in middle-aged mice correlate with lower exploratory activity and a subordinate status : role of hippocampal neurotrophins

The aim of the present work was to relate age‐related individual differences in cognitive function with behavioural strategies employed in social and non‐social challenges. To this purpose, the behaviour of adult (5‐month‐old) and middle‐aged (13‐month‐old) CD‐1 mice was scored in the social interaction, plus‐maze, Morris water maze (MWM) and open‐field tests. In addition, brain levels of nerve growth factor and brain‐derived neurotrophic factor (BDNF) were analysed and correlated with the behaviours scored. Compared to adults, middle‐aged mice showed greater anxiety in both non‐social and social situations, spending less time in the open arms of the plus‐maze and performing more freezing behaviour in response to aggression. Based upon their behaviour in the social interaction test, adult and middle‐aged subjects were classified as dominant or subordinate and their behaviour in the open field, plus‐maze and MWM tests subjected to factor analysis, taking into account age and social status. Results highlighted meaningful differences in exploratory strategies as a function of social status only in middle‐aged subjects. In particular, middle‐aged dominants were, overall, more explorative than same‐aged subordinates, spending less time in peripheral areas and approaching more readily a novel object. Interestingly, in middle‐aged mice, superior performance in the MWM task was associated with exploratory strategies exploited by dominants. At adulthood, BDNF hippocampal levels, but not specific behaviours, were positively correlated with the ability to learn a spatial task. Overall, data indicate that, in middle‐aged subjects individual differences in exploratory strategies, rather than neurotrophin levels, are able to predict the degree of impairment in a spatial learning task.

The role of high resolution pulsed and color Doppler ultrasound in the differential diagnosis of benign and malignant lymphadenopathy

The role of high resolution pulsed and color Doppler ultrasound in the differential diagnosis of benign and malignant lymphadenopathy is still unclear.

Autoantibodies to estrogen receptor α interfere with T lymphocyte homeostasis and are associated with disease activity in systemic lupus erythematosus

OBJECTIVE Estrogens influence many physiologic processes and are also implicated in the development or progression of numerous diseases, including autoimmune disorders. Aberrations of lymphocyte homeostasis that lead to the production of multiple pathogenic autoantibodies, including autoantibodies specific to estrogen receptor (ER), have been detected in the peripheral blood of patients with systemic lupus erythematosus (SLE). This study was undertaken to assess the presence of both anti-ERα and anti-ERβ antibodies in sera from patients with SLE, to analyze the effect of these antibodies on peripheral blood T lymphocyte homeostasis, and to evaluate their role as determinants of disease pathogenesis and progression. METHODS Anti-ER antibody serum immunoreactivity was analyzed by enzyme-linked immunosorbent assay in samples from 86 patients with SLE and 95 healthy donors. Phenotypic and functional analyses were performed by flow cytometry and Western blotting. RESULTS Anti-ERα antibodies were present in 45% of the patients with SLE, whereas anti-ERβ antibodies were undetectable. In healthy donors, anti-ERα antibodies induced cell activation and consequent apoptotic cell death in resting lymphocytes as well as proliferation of anti-CD3-stimulated T lymphocytes. A significant association between anti-ERα antibody values and clinical parameters, i.e., the SLE Disease Activity Index and arthritis, was found. CONCLUSION Our data suggest that anti-ERα autoantibodies interfere with T lymphocyte homeostasis and are significantly associated with lupus disease activity.