Bisphenol-A Exposure during Gestation and Lactation Causes Visual Perception Deficits in Rat Pups Following a Decrease in Interleukin 1β Expression in the Primary Visual Cortex

Developmental Programming in Animal Models: Critical Evidence of Current Environmental Negative Changes

The Developmental Origins of Health and Disease (DOHaD) approach answers questions surrounding the early events suffered by the mother during reproductive stages that can either partially or permanently influence the developmental programming of children, predisposing them to be either healthy or exhibit negative health outcomes in adulthood. Globally, vulnerable populations tend to present high obesity rates, including among school-age children and women of reproductive age. In addition, adults suffer from high rates of diabetes, hypertension, cardiovascular, and other metabolic diseases. The increase in metabolic outcomes has been associated with the combination of maternal womb conditions and adult lifestyle-related factors such as malnutrition and obesity, smoking habits, and alcoholism. However, to date, "new environmental changes" have recently been considered negative factors of development, such as maternal sedentary lifestyle, lack of maternal attachment during lactation, overcrowding, smog, overurbanization, industrialization, noise pollution, and psychosocial stress experienced during the current SARS-CoV-2 pandemic. Therefore, it is important to recognize how all these factors impact offspring development during pregnancy and lactation, a period in which the subject cannot protect itself from these mechanisms. This review aims to introduce the importance of studying DOHaD, discuss classical programming studies, and address the importance of studying new emerging programming mechanisms, known as actual lifestyle factors, during pregnancy and lactation.

Developmental Exposure to Bisphenol a Degrades Auditory Cortical Processing in Rats

Developmental exposure to bisphenol A (BPA), an endocrine-disrupting contaminant, impairs cognitive function in both animals and humans. However, whether BPA affects the development of primary sensory systems, which are the first to mature in the cortex, remains largely unclear. Using the rat as a model, we aimed to record the physiological and structural changes in the primary auditory cortex (A1) following lactational BPA exposure and their possible effects on behavioral outcomes. We found that BPA-exposed rats showed significant behavioral impairments when performing a sound temporal rate discrimination test. A significant alteration in spectral and temporal processing was also recorded in their A1, manifested as degraded frequency selectivity and diminished stimulus rate-following by neurons. These post-exposure effects were accompanied by changes in the density and maturity of dendritic spines in A1. Our findings demonstrated developmental impacts of BPA on auditory cortical processing and auditory-related discrimination, particularly in the temporal domain. Thus, the health implications for humans associated with early exposure to endocrine disruptors such as BPA merit more careful examination.

Does Bisphenol A Confer Risk of Neurodevelopmental Disorders? What We Have Learned from Developmental Neurotoxicity Studies in Animal Models

Substantial evidence indicates that bisphenol A (BPA), a ubiquitous environmental chemical used in the synthesis of polycarbonate plastics and epoxy resins, can impair brain development. Clinical and epidemiological studies exploring potential connections between BPA and neurodevelopmental disorders in humans have repeatedly identified correlations between early BPA exposure and developmental disorders, such as attention deficit/hyperactivity disorder and autism spectrum disorder. Investigations using invertebrate and vertebrate animal models have revealed that developmental exposure to BPA can impair multiple aspects of neuronal development, including neural stem cell proliferation and differentiation, synapse formation, and synaptic plasticity-neuronal phenotypes that are thought to underpin the fundamental changes in behavior-associated neurodevelopmental disorders. Consistent with neuronal phenotypes caused by BPA, behavioral analyses of BPA-treated animals have shown significant impacts on behavioral endophenotypes related to neurodevelopmental disorders, including altered locomotor activity, learning and memory deficits, and anxiety-like behavior. To contextualize the correlations between BPA and neurodevelopmental disorders in humans, this review summarizes the current literature on the developmental neurotoxicity of BPA in laboratory animals with an emphasis on neuronal phenotypes, molecular mechanisms, and behavioral outcomes. The collective works described here predominantly support the notion that gestational exposure to BPA should be regarded as a risk factor for neurodevelopmental disorders.

Hyperactivity of basolateral amygdala mediates behavioral deficits in mice following exposure to bisphenol A and its analogue alternative

Bisphenol A (BPA) is a known endocrine disruptor and has been gradually replaced in industrial applications by other bisphenols, such as bisphenol S (BPS). However, whether these analogues are any safer for the central nervous system remains elusive. Here, we investigated behavioral impairments in mice after BPA and BPS exposure from postnatal days 21-49 (P21~P49). Results showed that BPA (0.1 and 1 mg/kg/d) and BPS (1 mg/kg/d) impaired emotion and social interaction of mice, while low dose exposure (0.1 mg/kg/d) induced no observable changes on emotion in mice. The behavioral deficits were accompanied by hyperactivation of the basolateral amygdala (BLA), i.e., dose-dependent increase in neuronal firing rates and local field potential power. In addition, glutamate receptors were up-regulated in the BLA, showing the same activation trend after exposure to different doses of BPA and BPS. Taken together, these findings imply that BPA and BPS cause behavioral impairments in juvenile mice by disrupting local neuronal activation in the BLA. Although BPS exerted less adverse effects on mice than BPA at the low dose, it does not appear to be a safe alternative to BPA in regard to brain function after prolonged high-volume exposure.