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Role of late maternal thyroid hormones in cerebral cortex development: an experimental model for human prematurity.

Berbel P, Navarro D, Ausó E, Varea E, Rodríguez AE, Ballesta JJ, Salinas M, Flores E, Faura CC, de Escobar GM - Cereb. Cortex (2009)

Bottom Line: At P40, heterotopic neurons were found in the subcortical white matter and in the hippocampal stratum oriens and alveus.LMH pups showed delayed learning in parallel to decreased phosphorylated cAMP response element-binding protein (pCREB) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) expression in the hippocampus.In conclusion, maternal THs are still essential for normal offspring's neurodevelopment even after onset of fetal thyroid function.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Neurociencias, Universidad Miguel Hernández and Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain. pere.berbel@umh.es

ABSTRACT
Hypothyroxinemia affects 35-50% of neonates born prematurely (12% of births) and increases their risk of suffering neurodevelopmental alterations. We have developed an animal model to study the role of maternal thyroid hormones (THs) at the end of gestation on offspring's cerebral maturation. Pregnant rats were surgically thyroidectomized at embryonic day (E) 16 and infused with calcitonin and parathormone (late maternal hypothyroidism [LMH] rats). After birth, pups were nursed by normal rats. Pups born to LMH dams, thyroxine treated from E17 to postnatal day (P) 0, were also studied. In developing LMH pups, the cortical lamination was abnormal. At P40, heterotopic neurons were found in the subcortical white matter and in the hippocampal stratum oriens and alveus. The Zn-positive area of the stratum oriens of hippocampal CA3 was decreased by 41.5% showing altered mossy fibers' organization. LMH pups showed delayed learning in parallel to decreased phosphorylated cAMP response element-binding protein (pCREB) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) expression in the hippocampus. Thyroxine treatment of LMH dams reverted abnormalities. In conclusion, maternal THs are still essential for normal offspring's neurodevelopment even after onset of fetal thyroid function. Our data suggest that thyroxine treatment of premature neonates should be attempted to compensate for the interruption of the maternal supply.

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Confocal photomicrographs of the primary somatosensory cortex (A–C, G–I, J) and the hippocampal CA1 (D–F) of control (J, K) and LMH (A–I, L) pups at P40. Single labeling to BrdU (A, D, G) and to NeuN (B, E, H) and double labeling (C, F, I, J, yellow) are shown. Note that almost all BrdU-positive cells are neurons (double labeled with NeuN; C, F, I, J). Panels G–I show heterotopic neurons in the subcortical white matter (wm) of the primary somatosensory cortex in LMH pups (for comparisons between experimental groups and percentages, see Figure 6 and Supplementary Table 4). Immunofluorescence labeling of glial cells (BrdU positive and NeuN negative; arrows) in the primary somatosensory cortex of control (J) and LMH (G, I) pups. Glial cells in the hippocampal CA1 of LMH (D, F) pups are also indicated (arrows). Light microscope photomicrographs are shown of primary somatosensory cortex of control (K) and LMH (L) pups. Double-labeled astrocytes (arrows in K and L) are shown. Note that BrdU-labeled astrocytes show partial staining limited to clumped chromatin within the nuclei corresponding to type 3 labeling of Takahashi et al. (1992).
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fig3: Confocal photomicrographs of the primary somatosensory cortex (A–C, G–I, J) and the hippocampal CA1 (D–F) of control (J, K) and LMH (A–I, L) pups at P40. Single labeling to BrdU (A, D, G) and to NeuN (B, E, H) and double labeling (C, F, I, J, yellow) are shown. Note that almost all BrdU-positive cells are neurons (double labeled with NeuN; C, F, I, J). Panels G–I show heterotopic neurons in the subcortical white matter (wm) of the primary somatosensory cortex in LMH pups (for comparisons between experimental groups and percentages, see Figure 6 and Supplementary Table 4). Immunofluorescence labeling of glial cells (BrdU positive and NeuN negative; arrows) in the primary somatosensory cortex of control (J) and LMH (G, I) pups. Glial cells in the hippocampal CA1 of LMH (D, F) pups are also indicated (arrows). Light microscope photomicrographs are shown of primary somatosensory cortex of control (K) and LMH (L) pups. Double-labeled astrocytes (arrows in K and L) are shown. Note that BrdU-labeled astrocytes show partial staining limited to clumped chromatin within the nuclei corresponding to type 3 labeling of Takahashi et al. (1992).

Mentions: At P40, in C and LMH pups, the radial distribution of types 1 and 2 BrdU-immunoreactive cells in the primary somatosensory cortex (Fig. 1A–F and Fig. 2A–C) was consistent with that described previously by Bayer and Altman (1991) showing the normal “inside–out” gradient model of radial migration. In LMH pups, the proportion of BrdU-immunoreactive cells, after injections at E17 until P0, decreased in layers II–III and increased in layers IV, VI, and white matter compared with C and LMH + T4 pups (P < 0.05; Fig. 2D and Supplementary Table 3). At P40, double BrdU- and GFAP-immunolabeled cells were very scarce both in the neocortex and hippocampus (Fig. 3K,L). Double-labeled GFAP-labeled astrocytes showed disperse clumped BrdU-labeled chromatin and correspond to type 3 BrdU labeling described by Takahashi et al. (1992); these nuclei were not included in our plots and counts of BrdU-labeled cells. In contrast, all type 1 and 2 BrdU-labeled cells were also immunopositive for NeuN (Fig. 3A,J), both in the parietal cortex (Fig. 3A–C,G–H) and in hippocampal CA1 (Fig. 3D,F). Type 3 BrdU-positive and NeuN-negative cells accounted for less than 10% of the total NeuN-positive neurons (on average, 6.7 ± 2.1%).


Role of late maternal thyroid hormones in cerebral cortex development: an experimental model for human prematurity.

Berbel P, Navarro D, Ausó E, Varea E, Rodríguez AE, Ballesta JJ, Salinas M, Flores E, Faura CC, de Escobar GM - Cereb. Cortex (2009)

Confocal photomicrographs of the primary somatosensory cortex (A–C, G–I, J) and the hippocampal CA1 (D–F) of control (J, K) and LMH (A–I, L) pups at P40. Single labeling to BrdU (A, D, G) and to NeuN (B, E, H) and double labeling (C, F, I, J, yellow) are shown. Note that almost all BrdU-positive cells are neurons (double labeled with NeuN; C, F, I, J). Panels G–I show heterotopic neurons in the subcortical white matter (wm) of the primary somatosensory cortex in LMH pups (for comparisons between experimental groups and percentages, see Figure 6 and Supplementary Table 4). Immunofluorescence labeling of glial cells (BrdU positive and NeuN negative; arrows) in the primary somatosensory cortex of control (J) and LMH (G, I) pups. Glial cells in the hippocampal CA1 of LMH (D, F) pups are also indicated (arrows). Light microscope photomicrographs are shown of primary somatosensory cortex of control (K) and LMH (L) pups. Double-labeled astrocytes (arrows in K and L) are shown. Note that BrdU-labeled astrocytes show partial staining limited to clumped chromatin within the nuclei corresponding to type 3 labeling of Takahashi et al. (1992).
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fig3: Confocal photomicrographs of the primary somatosensory cortex (A–C, G–I, J) and the hippocampal CA1 (D–F) of control (J, K) and LMH (A–I, L) pups at P40. Single labeling to BrdU (A, D, G) and to NeuN (B, E, H) and double labeling (C, F, I, J, yellow) are shown. Note that almost all BrdU-positive cells are neurons (double labeled with NeuN; C, F, I, J). Panels G–I show heterotopic neurons in the subcortical white matter (wm) of the primary somatosensory cortex in LMH pups (for comparisons between experimental groups and percentages, see Figure 6 and Supplementary Table 4). Immunofluorescence labeling of glial cells (BrdU positive and NeuN negative; arrows) in the primary somatosensory cortex of control (J) and LMH (G, I) pups. Glial cells in the hippocampal CA1 of LMH (D, F) pups are also indicated (arrows). Light microscope photomicrographs are shown of primary somatosensory cortex of control (K) and LMH (L) pups. Double-labeled astrocytes (arrows in K and L) are shown. Note that BrdU-labeled astrocytes show partial staining limited to clumped chromatin within the nuclei corresponding to type 3 labeling of Takahashi et al. (1992).
Mentions: At P40, in C and LMH pups, the radial distribution of types 1 and 2 BrdU-immunoreactive cells in the primary somatosensory cortex (Fig. 1A–F and Fig. 2A–C) was consistent with that described previously by Bayer and Altman (1991) showing the normal “inside–out” gradient model of radial migration. In LMH pups, the proportion of BrdU-immunoreactive cells, after injections at E17 until P0, decreased in layers II–III and increased in layers IV, VI, and white matter compared with C and LMH + T4 pups (P < 0.05; Fig. 2D and Supplementary Table 3). At P40, double BrdU- and GFAP-immunolabeled cells were very scarce both in the neocortex and hippocampus (Fig. 3K,L). Double-labeled GFAP-labeled astrocytes showed disperse clumped BrdU-labeled chromatin and correspond to type 3 BrdU labeling described by Takahashi et al. (1992); these nuclei were not included in our plots and counts of BrdU-labeled cells. In contrast, all type 1 and 2 BrdU-labeled cells were also immunopositive for NeuN (Fig. 3A,J), both in the parietal cortex (Fig. 3A–C,G–H) and in hippocampal CA1 (Fig. 3D,F). Type 3 BrdU-positive and NeuN-negative cells accounted for less than 10% of the total NeuN-positive neurons (on average, 6.7 ± 2.1%).

Bottom Line: At P40, heterotopic neurons were found in the subcortical white matter and in the hippocampal stratum oriens and alveus.LMH pups showed delayed learning in parallel to decreased phosphorylated cAMP response element-binding protein (pCREB) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) expression in the hippocampus.In conclusion, maternal THs are still essential for normal offspring's neurodevelopment even after onset of fetal thyroid function.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Neurociencias, Universidad Miguel Hernández and Consejo Superior de Investigaciones Científicas, Sant Joan d'Alacant, Alicante, Spain. pere.berbel@umh.es

ABSTRACT
Hypothyroxinemia affects 35-50% of neonates born prematurely (12% of births) and increases their risk of suffering neurodevelopmental alterations. We have developed an animal model to study the role of maternal thyroid hormones (THs) at the end of gestation on offspring's cerebral maturation. Pregnant rats were surgically thyroidectomized at embryonic day (E) 16 and infused with calcitonin and parathormone (late maternal hypothyroidism [LMH] rats). After birth, pups were nursed by normal rats. Pups born to LMH dams, thyroxine treated from E17 to postnatal day (P) 0, were also studied. In developing LMH pups, the cortical lamination was abnormal. At P40, heterotopic neurons were found in the subcortical white matter and in the hippocampal stratum oriens and alveus. The Zn-positive area of the stratum oriens of hippocampal CA3 was decreased by 41.5% showing altered mossy fibers' organization. LMH pups showed delayed learning in parallel to decreased phosphorylated cAMP response element-binding protein (pCREB) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) expression in the hippocampus. Thyroxine treatment of LMH dams reverted abnormalities. In conclusion, maternal THs are still essential for normal offspring's neurodevelopment even after onset of fetal thyroid function. Our data suggest that thyroxine treatment of premature neonates should be attempted to compensate for the interruption of the maternal supply.

Show MeSH
Related in: MedlinePlus