Thyroxine normalizes polychlorinated biphenyl (PCB) dose-related depression of choline acetyltransferase (ChAT) activity in hippocampus and basal forebrain of 15-day-old rats

Ku, Laura M.Juárez de; Sharma-Stokkermans, Monica; Meserve, Lee A.

doi:10.1016/0300-483x(94)90025-6

Cited by 70 publications

(28 citation statements)

References 35 publications

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“…Rat pups exposed in utero to ortho-substituted but not coplanar PCB congeners have lower-thannormal dopamine levels in the basal forebrain in a manner analogous to what occurs in hypothyroidism (1,77). Rat pups either prenatally or lactationally exposed to PCBs have low ChAT activity in the hippocampus and basal forebrain (78). The results are the same as those seen in neonatally hypothyroid rats.…”

Section: Pcbs and Neurotransmitterssupporting

confidence: 58%

“…The results are the same as those seen in neonatally hypothyroid rats. Because PCB exposure lowered serum T4 levels, Juarez et al (78) treated some of the pups with T4 or T3 and found that T4, but not T3, returned ChAT activity almost to control levels, thereby suggesting that PCB-induced ChAT suppression could be mediated through the thyroidal system.…”

Section: Pcbs and Neurotransmittersmentioning

confidence: 99%

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Thyroidal dysfunction and environmental chemicals--potential impact on brain development.

Porterfield

2000

Environ Health Perspect

137

129

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Certain polyhalogenated aromatic hydrocarbons such as polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins (dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin) have been shown to have neurotoxic effects and to alter thyroid function during critical periods of thyroid hormone-dependent brain development. This has led to the suggestion that some of the neurotoxic effects of these compounds could be mediated through the thyroid system. Thyroid hormones are essential for normal brain development during a critical period beginning in utero and extending through the first 2 years postpartum. They regulate neuronal proliferation, migration, and differentiation in discrete regions of the brain during definitive time periods. Even transient disruption of this normal pattern can impair brain development. Thyroid hormones are necessary for normal cytoskeletal assembly and stability and the cytoskeletal system is essential for migration and neuronal outgrowth. In addition, they regulate development of cholinergic and dopaminergic systems serving the cerebral cortex and hippocampus. Animals perinatally exposed to certain environmental organohalogens such as many of the PCBs and dioxins have abnormal thyroid function and neurologic impairment. Although there are both species and congener variabilities, most reports show exposure results in thyroid enlargement and reduced serum T4 levels with normal T3 levels. Initial research concentrated on studying the direct actions of xenobiotics on the thyroid; however, some of these compounds bear a structural resemblance to the natural thyroid hormones and have high affinity with thyroid hormone-binding proteins such as transthyretin. These compounds could act as agonists or antagonists for receptors of the thyroid/steroid/retinoic acid superfamily. These structurally similar organohalogens could act at multiple points to alter thyroid hormone action. The similarity of the neurologic impairment seen in thyroid disorders to that seen following PCB or dioxin exposure suggests that one mechanism of neurotoxicity of these compounds could involve interaction with the thyroid system.

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Section: Pcbs and Neurotransmitterssupporting

confidence: 58%

Section: Pcbs and Neurotransmittersmentioning

confidence: 99%

Thyroidal dysfunction and environmental chemicals--potential impact on brain development.

Porterfield

2000

Environ Health Perspect

137

129

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“…For instance, development of the CNS cholinergic neurons is exquisitely sensitive to the thyroid status. In rats, perinatal exposure to some PCBs (specific congeners or mixtures such as Aroclor 1254) has been shown to lower serum T4 and reduce choline acetyltransferase (ChAT) activity (228) in the hippocampus and basal forebrain. ChAT is an enzyme involved in the synthesis of acetylcholine, a neurotransmitter considered important to learning and memory.…”

Section: S=c\r-mentioning

confidence: 99%

Environmental Endocrine Disruption: An Effects Assessment and Analysis

Crisp¹,

Clegg²,

Cooper³

et al. 1998

Environmental Health Perspectives

165

145

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“…Other work has focused on the cognitive impairments caused by exposure to PCBs [2,23,24]. Meserve and colleagues [25][26][27] have focused on the relationship between cognition and PCB-induced hormonal and neural alterations. Studies found that animals exposed to PCBs have depressed choline acetyltransferase activity [25] and deficits in working and spatial memory as revealed by performance in the radial arm maze and Morris water maze tasks [26,27].…”

Section: Introductionmentioning

confidence: 99%

“…Meserve and colleagues [25][26][27] have focused on the relationship between cognition and PCB-induced hormonal and neural alterations. Studies found that animals exposed to PCBs have depressed choline acetyltransferase activity [25] and deficits in working and spatial memory as revealed by performance in the radial arm maze and Morris water maze tasks [26,27]. Several of these cognitive behavioral alterations have been found to be most prominent in juvenile animals (15-30 days of age) compared to young adulthood (~60 days of age).…”

Section: Introductionmentioning

confidence: 99%

Effects of polychlorinated biphenyls on maternal odor conditioning in rat pups

Cromwell

Johnson

McKnight

et al. 2007

Physiology & Behavior

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Polychlorinated biphenyls (PCBs) are pervasive environmental contaminants that can have damaging effects on physiologic, motoric and cognitive function. Results from studies on PCBs and behavior have shown that exposure can alter learning and memory processes and that these shifts in cognitive abilities can be related to changes in hormonal and neural function. Little experimentation has been done on the impact of exposure to PCBs on social and emotional development. Previous work has shown that exposure to PCBs in children can alter play behavior. Importantly, exposure to PCBs has been found to change aspects of maternal-offspring interactions in rodents. The present study examined the impact of PCBs on maternal odor conditioning in rat pups 12-14 days of age. A modified version of the conditioned place preference paradigm was used that incorporated a maternal-associated odor cue (lemon scent) as the conditioned stimulus. PCBs significantly depressed the preference for the maternal-associated cue but did not impair discrimination for a novel odor. These effects could arise due to changes in the social dynamics between the dam and offspring after co-exposure to PCBs. For example, dams exposed to PCBs during gestation have been found to show elevated grooming directed towards pups exposed to PCBs. This change in maternal care can have dramatic effects on behavioral and hormonal systems in the developing rat pup. In conclusion, perinatal PCBs alter important social behaviors of both the mother and pup, and these alterations could have long-lasting effects on behavioral, cognitive and emotional development.

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Thyroxine normalizes polychlorinated biphenyl (PCB) dose-related depression of choline acetyltransferase (ChAT) activity in hippocampus and basal forebrain of 15-day-old rats

Cited by 70 publications

References 35 publications

Thyroidal dysfunction and environmental chemicals--potential impact on brain development.

Thyroidal dysfunction and environmental chemicals--potential impact on brain development.

Environmental Endocrine Disruption: An Effects Assessment and Analysis

Effects of polychlorinated biphenyls on maternal odor conditioning in rat pups

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