Dataset Information

Preclinical modeling of exposure to a global marine bio-contaminant: Effects of in utero Domoic acid exposure on neonatal behavior and infant memory.

ABSTRACT: Domoic Acid (DA) is a naturally-occurring marine neurotoxin that is increasingly recognized as an important public health issue. Prenatal DA exposure occurs through the maternal consumption of contaminated shellfish/finfish. To better understand the fetal risks associated with DA, we initiated a longitudinal, preclinical study focused on the reproductive and developmental effects of chronic, low-dose oral DA exposure. To this end, 32 adult female Macaca fascicularis monkeys were orally dosed with 0, 0.075 or 0.15?mg/kg/day DA on a daily basis prior to breeding and throughout breeding and pregnancy. The doses included the proposed human Tolerable Daily Intake (TDI) (0.075?mg/kg/day) for DA. Adult females were bred to nonexposed males. To evaluate development during early infancy, offspring were administered a Neonatal Assessment modeled after the human Neonatal Behavior Assessment Scale and a series of Visual Recognition Memory problems using the novelty paradigm. Results indicated that prenatal DA exposure did not impact early survival reflexes or responsivity to the environment. Findings from the recognition memory assessment, given between 1 and 2?months of age, showed that exposed and control infants demonstrated robust novelty scores when test problems were relatively easy to solve. Performance was not diminished by the introduction of delay periods. However, when more difficult recognition problems were introduced, the looking behavior of the 0.15?mg/kg DA group was random and infants failed to show differential visual attention to novel test stimuli. This finding suggests subtle but significant impairment in recognition memory and demonstrates that chronic fetal exposure to DA may impact developing cognitive processes.

SUBMITTER: Grant KS

PROVIDER: S-EPMC6511476 | biostudies-literature | 2019 May - Jun

REPOSITORIES: biostudies-literature

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Preclinical modeling of exposure to a global marine bio-contaminant: Effects of in utero Domoic acid exposure on neonatal behavior and infant memory.

Grant Kimberly S KS Crouthamel Brenda B Kenney Caroline C McKain Noelle N Petroff Rebekah R Shum Sara S Jing Jing J Isoherranen Nina N Burbacher Thomas M TM

Neurotoxicology and teratology 20190125

Domoic Acid (DA) is a naturally-occurring marine neurotoxin that is increasingly recognized as an important public health issue. Prenatal DA exposure occurs through the maternal consumption of contaminated shellfish/finfish. To better understand the fetal risks associated with DA, we initiated a longitudinal, preclinical study focused on the reproductive and developmental effects of chronic, low-dose oral DA exposure. To this end, 32 adult female Macaca fascicularis monkeys were orally dosed wit ...[more]

PMID: 30690118

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Project description:Domoic acid (DA) is a naturally produced neurotoxin synthesized by the marine diatom genus Pseudo-nitzschia. DA accumulates in filter-feeders such as shellfish, and can produce severe neurotoxicity when contaminated seafood is ingested. DA poisoning is a significant public health concern, and though seafood regulations have effectively minimized the human risk of severe acute poisoning, the effects of exposure at asymptomatic levels are poorly understood. The objective of this study was to determine the effects of exposure to symptomatic and asymptomatic doses of DA on gene expression patterns in the zebrafish brain. We exposed adult zebrafish to either a symptomatic (1.1 ± 0.2 μg /g) or an asymptomatic (0.31 ± 0.03 µg DA/g fish) dose of DA by intracelomic injection and sampled at 24, 48 and 168 h post-injection. Transcriptional profiling was done using Agilent and Affymetrix microarrays. Our analysis revealed distinct, non-overlapping changes in gene expression between the two doses. We found that the majority of transcriptional changes were observed at 24 hours post-injection with both doses. In response to symptomatic dose exposure, we observed 328, 5, and 1 genes were differentially expressed at 24, 48 and 168 hours post-injection, respectively. In contrast, 136, 12, and 28 genes were differentially expressed in the asymptomatic dose at the same time points. Pathway analysis revealed symptomatic DA exposure affected genes associated with pathways including cell adhesion, inflammation, and amyloid proteins. Among the pathways enriched among genes differentially expressed with asymptomatic exposure were circadian rhythms and endocrine signaling. Overall, these results suggest that transcriptional responses are specific to the DA dose and that asymptomatic exposure can cause long-term changes. Many of the differentially expressed genes are important players in neuronal, neuroimmune and neuroendocrine function. Further studies are needed to characterize the potential downstream neurobehavioral impacts of DA exposure.

Project description:The opioid epidemic is an ongoing public health crisis, and children born following prenatal opioid exposure (POE) have increased risk of long-term cognitive and behavioral sequelae. Clinical studies have identified reduced gray matter volume and abnormal white matter microstructure in children with POE but impacts on whole-brain functional brain connectivity (FC) have not been reported. To define effects of POE on whole brain FC and white matter injury in adult animals, we performed quantitative whole-brain structural and functional MRI. We used an established rat model of POE in which we have previously reported impaired executive function in adult rats analogous to persistent neurocognitive symptoms described in humans with POE. Pregnant Sprague-Dawley rat dams received continuous methadone (12 mg/kg/day) vs. saline infusion for 28 days via osmotic mini-pumps, exposing rats to pre- and postnatal opioid until weaning. At young adult age (P60), POE and saline exposed offspring underwent in vivo MRI included diffusion tensor imaging and functional MRI (fMRI). Results indicate that fractional anisotropy (FA) was decreased in adult animals with POE [n = 11] compared to animals that received saline [n = 9] in major white matter tracts, including the corpus callosum (p < 0.001) and external capsule (p < 0.01). This change in FA was concomitant with reduced axial diffusivity in the external capsule (p < 0.01) and increased radial diffusivity in the corpus callosum (p < 0.01). fMRI analyses reveal brainwide FC was diffusely lower in POE (p < 10-6; 10% of variance explained by group). Decreased connectivity in cortical-cortical and cortico-basal ganglia circuitry was particularly prominent with large effect sizes (Glass's Δ > 1). Taken together, these data confirm POE reduces brainwide functional connectivity as well as microstructural integrity of major white matter tracts. Altered neural circuitry, dysregulated network refinement, and diffuse network dysfunction have been implicated in executive function deficits that are common in children with POE. FC may serve as a translatable biomarker in children with POE.

Dataset Information

Preclinical modeling of exposure to a global marine bio-contaminant: Effects of in utero Domoic acid exposure on neonatal behavior and infant memory.

Publications

Preclinical modeling of exposure to a global marine bio-contaminant: Effects of in utero Domoic acid exposure on neonatal behavior and infant memory.

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