Exposure to PCB 77 induces tissue-dependent changes in iodothyronine deiodinase activity patterns in the embryonic chicken

Beck, Veronika; Roelens, Simon; Darras, Veerle

doi:10.1016/j.ygcen.2006.04.003

Cited by 31 publications

(11 citation statements)

References 49 publications

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“…It could further be demonstrated that, as in late gestational rat fetuses, an adaptive increase in type 2 deiodinase activity occurred both in telencephalon and cerebellum. In addition, an also adaptive decrease in the activity of the T 3 inactivating type 3 deiodinase was observed in cerebellum but not in telencephalon (33). This could indicate that the maintenance of T 3 homeostasis in the developing cerebellum is even more critical than in telencephalon.…”

Section: Neurodevelopmental Effects Of Pcbsmentioning

confidence: 90%

Endocrine disrupting polyhalogenated organic pollutants interfere with thyroid hormone signalling in the developing brain

Darras¹

2008

Cerebellum

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Persistent polyhalogenated organic pollutants are present worldwide and accumulate along the food chain. They interfere with human and animal health and are particularly harmful for pre- and perinatal neurodevelopment. The mechanisms behind the observed effects vary depending on the specific compound investigated. Co-planar polychlorinated biphenyls (PCBs) can act via the arylhydrocarbon receptor while many ortho-substituted PCBs disrupt intracellular Ca(2+) homeostasis. A common mechanism for a wide variety of PCBs is interference with thyroid hormone (TH) signalling in developing brain, by changing intracellular TH availability or by interacting directly at the level of the TH receptors. Studies on gene expression in cortex and cerebellum revealed both hypothyroid- and hyperthyroid-like effects. However, since THdependent gene expression plays a crucial role in the coordination of neuronal proliferation, migration, synaptogenesis, myelination, etc., both reduced/delayed and increased/premature expression may result in permanent structural changes in neuronal communication networks, leading to lifelong deficits in cognitive performance, motor functions, and psychobehavior. In a similar way, PCBs are able to interfere with estrogen- and androgen-dependent brain development and in some studies neurobehavioral outcome was shown to be gender-specific. Other persistent organohalogens like polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs) also act as endocrine disrupters in the developing brain. Several of the mechanisms involved are similar to those of PCBs, but each group also works via own specific pathways. The fact that persistent organohalogens can amplify the neurotoxic effects of other environmental pollutants, such as heavy metals, further increases their risk for human and animal neurodevelopment.

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Section: Neurodevelopmental Effects Of Pcbsmentioning

confidence: 90%

Endocrine disrupting polyhalogenated organic pollutants interfere with thyroid hormone signalling in the developing brain

Darras¹

2008

Cerebellum

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“…Primary hypothyroidism may also result from exposure to polyhalogenated aromatic hydrocarbons (383) and bisphenol A (384). The effects of polychlorinated biphenyls (PCBs) include increased hepatic degradation of thyroid hormones and inhibition of deiodinase activity, which applies predominantly to cerebral D3 (385–387). Typical high-T3 syndromes under PCB exposure are therefore probably caused by decreased D3 activity rather than by stimulated D1 or D2 activity.…”

Section: Effects Of Heterogeneous or Unknown Originmentioning

confidence: 99%

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

Hoermann²,

et al. 2017

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The hypothalamus–pituitary–thyroid feedback control is a dynamic, adaptive system. In situations of illness and deprivation of energy representing type 1 allostasis, the stress response operates to alter both its set point and peripheral transfer parameters. In contrast, type 2 allostatic load, typically effective in psychosocial stress, pregnancy, metabolic syndrome, and adaptation to cold, produces a nearly opposite phenotype of predictive plasticity. The non-thyroidal illness syndrome (NTIS) or thyroid allostasis in critical illness, tumors, uremia, and starvation (TACITUS), commonly observed in hospitalized patients, displays a historically well-studied pattern of allostatic thyroid response. This is characterized by decreased total and free thyroid hormone concentrations and varying levels of thyroid-stimulating hormone (TSH) ranging from decreased (in severe cases) to normal or even elevated (mainly in the recovery phase) TSH concentrations. An acute versus chronic stage (wasting syndrome) of TACITUS can be discerned. The two types differ in molecular mechanisms and prognosis. The acute adaptation of thyroid hormone metabolism to critical illness may prove beneficial to the organism, whereas the far more complex molecular alterations associated with chronic illness frequently lead to allostatic overload. The latter is associated with poor outcome, independently of the underlying disease. Adaptive responses of thyroid homeostasis extend to alterations in thyroid hormone concentrations during fetal life, periods of weight gain or loss, thermoregulation, physical exercise, and psychiatric diseases. The various forms of thyroid allostasis pose serious problems in differential diagnosis of thyroid disease. This review article provides an overview of physiological mechanisms as well as major diagnostic and therapeutic implications of thyroid allostasis under a variety of developmental and straining conditions.

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“…Blood samples obtained from cervical arteries before killing the birds were collected in heparinised tubes and immediately centrifuged. The plasma was stored at À20 C until T 3 and T 4 were assayed by radioimmunoassay (RIA) as previously described (Beck et al, 2006). All samples were analysed in a single assay.…”

Section: Plasma Thyroid Hormone Concentrationsmentioning

confidence: 99%

Divergent selection for shape of growth curve in Japanese quail. 4. Carcase composition and thyroid hormones

Hyánková

Novotná

Darras

2008

British Poultry Science

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1. Changes in the relative weights of carcase, abdominal fat, breast and leg muscles, and plasma thyroid hormone concentrations occurring during the first 6 weeks of postnatal growth were analysed in males of HG and LG lines divergently selected for high and low relative body weight (BW) gain between 11 and 28 d of age, respectively, and constant adult BW. 2. The second week of postnatal life was a critical age at which the HG males exhibited a relatively faster growth in comparison to their LG counterparts and permanently exceeded LG males in the percentage by weight of carcase, breast and leg muscle. A higher production of muscle tissues was associated with lower accumulation of abdominal fat before sexual maturity. 3. In general, the plasma T(3) level of HG quail exceeded that of LG quail. Nevertheless, significant differences were found only at 14, 21 and 28 d of age, that is, in the period during which the highest inter-line differences in relative growth rate were noted. Also the T(3)/T(4) ratio followed a similar trend while plasma T(4) level showed no clear and consistent inter-line differences. 4. The results suggest that the selection for the shape of the growth curve, like the selection for body fat, modifies the carcase quality owing to shortening/prolongation of the acceleration growth phase. Individuals with a short acceleration phase of the growth curve are characterised by low carcase quality during the fattening period.

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Exposure to PCB 77 induces tissue-dependent changes in iodothyronine deiodinase activity patterns in the embryonic chicken

Cited by 31 publications

References 49 publications

Endocrine disrupting polyhalogenated organic pollutants interfere with thyroid hormone signalling in the developing brain

Endocrine disrupting polyhalogenated organic pollutants interfere with thyroid hormone signalling in the developing brain

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

Divergent selection for shape of growth curve in Japanese quail. 4. Carcase composition and thyroid hormones

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