Sociability: Comparing the Effect of Chlorpyrifos with Valproic Acid

In recent years, exposures to organophosphate pesticide have been highlighted as a possible cause or aggravating factor of autism spectrum disorder (ASD). The present study examined if Wistar rats prenatally exposed to chlorpyrifos (CPF) at a dose of 1 mg/kg in GD 12.5-15.5 could express similar behaviors to those exposed to valproic acid (VPA, 400 mg/kg) during the same administration window, which is an accepted animal model of autism. The 3-chambered test was employed to evaluate sociability and reaction to social novelty in two experiments, the first in adolescence and the second in adulthood. The results obtained in this study show that animals prenatally treated with CPF or VPA show a similar behavioral phenotype compared to the control group (CNT). In adolescence, the CPF animals showed a negative index in the reaction to social novelty, followed closely by the VPA, while both experimental groups showed a recovery in this aspect during adulthood. This study therefore provides evidence to suggest that prenatal exposure to CPF in rats could have similar effects on certain components of sociability to those seen in autistic models.

Neurodevelopmental consequences of gestational exposure to particulate matter 10: Ultrasonic vocalizations and gene expression analysis using a bayesian approach

Air pollution has been associated with a wide range of health issues, particularly regarding cardio-respiratory diseases. Increasing evidence suggests a potential link between gestational exposure to environmental pollutants and neurodevelopmental disorders such as autism spectrum disorder. The respiratory pathway is the most commonly used exposure model regarding PM due to valid and logical reasons. However, PM deposition on food (vegetables, fruits, cereals, etc.) and water has been previously described. Although this justifies the need of unforced, oral models of exposure, preclinical studies using oral exposure are uncommon. Specifically, air pollution can modify normal brain development at genetic, cellular, and structural levels. The present work aimed to investigate the effects of oral gestational exposure to particulate matter (PM) on ultrasonic vocalizations (USV). To this end, pregnant rats were exposed to particulate matter during gestation. The body weight of the pups was monitored until the day of recording the USVs. The results revealed that the exposed group emitted more USV calls when compared to the control group. Furthermore, the calls from the exposed group were longer in duration and started earlier than those from the non-exposed group. Gene expression analyses showed that PM exposure down-regulates the expression of Gabrg2 and Maoa genes in the brain, but no effect was detected on glutamate or other neurotransmission systems. These findings suggest that gestational exposure to PM10 may be related to social deficits or other phenomena that can be analyzed with USV. In addition, we were able to detect abnormalities in the expression of genes related to different neurotransmitter systems, such as the GABAergic and monoaminergic systems. Further research is needed to fully understand the possible effects of air pollutant exposure on neurodevelopmental disorders as well as the way in which these effects are linked to differences in neurotransmission systems.

Uncovering the link between air pollution and neurodevelopmental alterations during pregnancy and early life exposure: A systematic review

Air pollution plays, nowadays, a huge role in human's health and in the personal economy. Moreover, there has been a rise in the prevalence of neurodevelopmental disorders like the Autism Spectrum Disorder (ASD) in recent years. Current scientific studies have established a link between prenatal or perinatal exposure to environmental pollutants and ASD. This systematic review summarizes the current literature available about the relationship between exposure to air pollutants (particulate matter [PM], Second Organic Aerosols [SOA], Diesel Exhaust [DE], and Traffic Related Air Pollution [TRAP]) and neurodevelopmental disorders in preclinical models using rats and mice. The articles were selected and filtered using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, and bias-evaluated using the SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) tool. Overall, our findings suggest that air pollutants are associated with negative developmental outcomes characterized by ASD-like behaviors, abnormal biochemical patterns, and impaired achievement of developmental milestones in rodents. However, there is not sufficient information in certain domains to establish a clear relationship. Short phrases for indexing terms: Air pollution affects neurodevelopment; PM exposure modifies glutamate system; Prenatal exposure combined with postnatal affect more to behavioral / cognitive domain; Air pollution modifies social behavior in rodents; Cognitive deficits can be detected after gestational exposure to air pollution.

Influence of Gestational Chlorpyrifos Exposure on ASD-like Behaviors in an fmr1-KO Rat Model

Based on previous reports, exposure to pesticides could be linked to the prevalence increase of autism spectrum disorders (ASD). Gestational exposure to chlorpyrifos (CPF) has been associated with ASD diagnosis in humans and ASD-like behaviors in rodents. However, ASD severity degree results from the complex relationship between genetic background and environmental factors. Thus, animals with a genetic vulnerability and prenatally exposed to CPF could have a more severe ASD-like phenotype. Fragile X syndrome is one of the most common monogenic causes of ASD, characterized by a mutation in the X chromosome which alters the expression of the fragile X mental retardation protein (FMRP). Based on this, some fmr1 knockout (KO) rodent models have been developed to study the physiological and genetic basis of ASD. Both fmr1-KO and wild-type male rats (F2 generation) were used in the present study. F1 pregnant females were randomly exposed to 1 mg/kg/mL/day of CPF (s.c.) from GD12.5-15.5 or vehicle. Different behavioral, developmental, and molecular variables were analyzed in F2 males. KO rats were heavier, emitted altered USVs, were socially inefficient, reacted more to a novel stimulus, were hyperactive when exploring a new context, but hypoactive when exploring anxiety-inducing environments, and had an upregulated hippocampal expression of the grin2c gene. When exposed to low doses of CPF during gestation, these KO rats showed decreased climbing capacity, dysfunctional social interaction, and increased hippocampal expression for kcc1 and 5ht2c genes. Gestational CPF exposure increased the ASD-like phenotype in those animals with a genetic vulnerability, although its effect was less generalized than expected. It is the first time that this additive effect of CPF exposure and the fmr1-KO genetic vulnerability model is explored concerning social traits or any other behavior.

Pesticides and aging: Preweaning exposure to Chlorpyrifos induces a general hypomotricity state in late-adult rats

The molecular and behavioral effects of the developmental exposure to low doses of Chlorpyrifos (CPF) have been intensively studied in young (neonates and adolescents), and adult animals. However, no study examined influences of developmental CPF exposure in older adult or geriatric rats. This is relevant as such ages are generally linked to cognitive decline and the onset of specific neurodegenerative disorders, some of them previously associated with CPF exposure in both preclinical and human studies. 1 mg/kg/mL of CPF was orally administered to both male and female Wistar rats from Postnatal day 10 to 15. Animals' spatial memory, learning, compulsivity, motricity, and anxiety were analyzed with Morris Water Maze (15-16 months of age) and the Plus-maze (at 18 months of age). Results showed that postnatal CPF exposure did not alter either spatial memory, compulsive-like behaviors, or anxiety levels in late-adult rats. However, CPF exposed rats were hyposensitive to brief disruptions (Probe stage) following the learning phase and showed a general decrease in locomotor activity in both paradigms. These data are relevant as it is the first time that developmental exposure to CPF has been studied at such a late age, observing important effects in locomotor activity that could be linked to specific pathologies previously associated with CPF effects in people. Future studies should extend these findings to other behaviors and molecular outcomes.

Medium and long-term effects of low doses of Chlorpyrifos during the postnatal, preweaning developmental stage on sociability, dominance, gut microbiota and plasma metabolites

Autism spectrum disorder (ASD) is a complex neurodevelopmental pathology characterized by altered verbalizations, reduced social interaction behavior, and stereotypies. Environmental factors have been associated with its development. Some researchers have focused on pesticide exposure. Chlorpyrifos (CPF) is the most used Organophosphate. Previous developmental studies with CPF showed decreased, enhanced or no effect on social outcomes eminently in mice. The study of CPF exposure during preweaning stages on social behavior is sparse in mice and non-existent in rats. d stressors could be at the basis of ASD development, and around postnatal day 10 in the rat is equivalent to the human birthday in neurodevelopmental terms. We explored the effects of exposure to low doses (1mg/kg/mL/day) of CPF during this stage regarding: sociability, dominance gut microbiome and plasma metabolomic profile, since alterations in these systems have also been linked to ASD. There was a modest influence of CPF on social behavior in adulthood, with null effects during adolescence. Dominance and hierarchical status were not affected by exposure. Dominance status explained the significant reduction in reaction to social novelty observed on the sociability test. CPF induced a significant gut microbiome dysbiosis and triggered a hyperlipidemic, hypoglycemic/hypogluconeogenesis and a general altered cell energy production in females. These behavioral results in rats extend and complement previous studies with mice and show novel influences on gut metagenomics and plasma lipid profile and metabolomics, but do not stablish a relation between the exposure to CPF and the ASD phenotype. The effects of dominance status on reaction to social novelty have an important methodological meaning for future research on sociability.

Age-dependent effects of repeated methamphetamine exposure on locomotor activity and attentional function in rats

Many adolescents use amphetamines which are the second most common abused illegal drugs. Methamphetamine (Meth), as a potent amphetamine affects attentional functions. However, the most significant factor for susceptibility to Meth is the age of exposure, most studies have examined the effects of Meth after early adolescence stage. The present experiment was aimed to investigate some possible short- and long-term effects of Meth at two distinct points of adolescence stage (early versus late) on 1) locomotor activity in adolescent rats and 2) attentional functions in their adulthood. Rats received Meth (5 mg/kg, i.p., for consecutive 10 days) during early adolescence (postnatal days (PND) 30-39) or late adolescence (PND 50-59). Locomotor activity was assessed after the first and tenth injections. Then, in adulthood, rats were trained and tested on the Five-choice serial reaction time task (5-CSRTT) to display possible attentional impairments. The first Meth administration in early exposed adolescent (EEA) group produced the highest level of activity, compared with the first exposure in late exposed adolescent (LEA) group and tenth administrations in both groups. In adulthood, LEA group significantly delayed learning the 5-CSRTT and exhibited attentional impairments, as demonstrated by significant reduced response accuracy and increased omission errors under pharmacological challenge, compared with control group. The susceptibility to Meth depends on the age of exposure and Meth administration during late adolescence stage may cause prolonged attentional deficits in adulthood.

A Systematic Review on the Influences of Neurotoxicological Xenobiotic Compounds on Inhibitory Control

Background: Impulsive and compulsive traits represent a variety of maladaptive behaviors defined by the difficulties to stop an improper response and the control of a repeated behavioral pattern without sensitivity to changing contingencies, respectively. Otherwise, human beings are continuously exposed to plenty neurotoxicological agents which have been systematically linked to attentional, learning, and memory dysfunctions, both preclinical and clinical studies. Interestingly, the link between both impulsive and compulsive behaviors and the exposure to the most important xenobiotic compounds have been extensively developed; although the information has been rarely summarized. For this, the present systematic review schedule and analyze in depth the most important works relating different subtypes of the above-mentioned behaviors with 4 of the most important xenobiotic compounds: Lead (Pb), Methylmercury (MeHg), Polychlorinated biphenyls (PCB), and Organophosphates (OP) in both preclinical and clinical models.

Methods: Systematic search strategy on PubMed databases was developed, and the most important information was structured both in text and in separate tables based on rigorous methodological quality assessment.

Results: For Lead, Methylmercury, Polychlorinated biphenyls and organophosphates, a total of 44 (31 preclinical), 34 (21), 38 (23), and 30 (17) studies were accepted for systematic synthesis, respectively. All the compounds showed an important empirical support on their role in the modulation of impulsive and, in lesser degree, compulsive traits, stronger and more solid in animal models with inconclusive results in humans in some cases (i.e., MeHg). However, preclinical and clinical studies have systematically focused on different subtypes of the above-mentioned behaviors, as well as impulsive choice or habit conformations have been rarely studied.

Discussion: The strong empirical support in preclinical studies contrasts with the lack of connection between preclinical and clinical models, as well as the different methodologies used. Further research should be focused on dissipate these differences as well as deeply study impulsive choice, decision making, risk taking, and cognitive flexibility, both in experimental animals and humans.

Streptococcus pneumoniae skin and soft tissue infections: characterization of causative strains and clinical illness

Streptococcus pneumoniae is an uncommon cause of skin and soft tissue infections, yet the incidence and clinical significance of its isolation in samples of skin or soft tissues in unselected hospital samples is poorly understood. In the present study, a review was conducted of the records of all patients with skin and soft tissue infections due to S. pneumoniae at a university hospital between January 1994 and December 2005. The isolates were identified by standard methods and were serotyped, and susceptibility testing was performed by the broth microdilution method following the guidelines of the Clinical and Laboratory Standards Institute. During the study period, 3,201 isolates of S. pneumoniae were recovered from several sources. Of these, 69 (2.2%) were from skin and soft tissue samples (69 patients). Complete information could not be obtained for 13 patients. Of the 56 patients remaining, 36 (64.3%) were infected and fulfilled the inclusion criteria. The following types of infections were observed: surgical wound infection (n = 11), burn infection (n = 7), pyomyositis (n = 6), cellulitis (n = 4), perineal or scrotal abscess (n = 3), and other (n = 5). Thirty-one (86%) patients had a favorable outcome, and 5 (13.8%) patients died. Mortality was directly attributable to S. pneumoniae infection in three of the five fatal cases. Of the 39 S. pneumoniae isolates obtained (36 from skin and soft tissues, three from blood cultures), 58.9% were penicillin nonsusceptible, 7.7% were cefotaxime nonsusceptible, and 20.5% were erythromycin resistant. The most frequent serotypes were 3, 19, 11, and 23. Of the overall number of isolates of S. pneumoniae recovered in a general institution, 2.2% involved skin and soft tissues (of which 64% were clinically significant). Mortality due to pneumococcal skin and soft tissue infections was low.