Perinatal periodontal disease reduces social behavior in male offspring.

OBJECTIVE: Our objective was to verify whether prenatal maternal periodontitis is a risk factor for the development of central nervous system disorders in rats. METHODS: Periodontitis was induced by placing a ligature around the upper and lower first molars in 9 female Wistar rats (experimental group); 9 rats were left unligated (control group). The maternal general activity in an open field was observed on gestational day (GD) 0, GD 4, and GD 14, and the maternal performance was assessed on the second day after birth. The pups' play behavior was assessed on postnatal day 30. The relative level of reelin was measured in the frontal cortex by real-time PCR analysis. RESULTS: The results showed that, compared with the control group, (1) the general activity in female rats with periodontitis was decreased, (2) the maternal performance of these rats was not modified by periodontitis, (3) the play behavior of pups from dams with periodontitis was decreased, and (4) there were no differences in the frontal cortex reelin levels of pups from dams with periodontitis. CONCLUSIONS: We conclude that pre- and postnatal periodontitis induces maternal sickness behavior and reduces the pups' play behavior without interference with frontal cortex reelin expression.

Synthesis of transthyretin by the ependymal cells of the subcommissural organ.

Transthyretin (TTR) is a protein involved in the transport of thyroid hormones in blood and cerebrospinal fluid (CSF). The only known source of brain-produced TTR is the choroid plexus. In the present investigation, we have identified the subcommissural organ (SCO) as a new source of brain TTR. The SCO is an ependymal gland that secretes glycoproteins into the CSF, where they aggregate to form Reissner's fibre (RF). Evidence exists that the SCO also secretes proteins that remain soluble in the CSF. To investigate the CSF-soluble compounds secreted by the SCO further, antibodies were raised against polypeptides partially purified from fetal bovine CSF. One of these antibodies (against a 14-kDa compound) reacted with secretory granules in cells of fetal and adult bovine SCO, organ-cultured bovine SCO and the choroid plexus of several mammalian species but not with RF. Western blot analyses with this antibody revealed two polypeptides of 14 kDa and 40 kDa in the bovine SCO, in the conditioned medium of SCO explants, and in fetal and adult bovine CSF. Since the monomeric and tetrameric forms of TTR migrate as bands of 14 kDa and 40 kDa by SDS-polyacrylamide gel electrophoresis, a commercial preparation of human TTR was run, with both bands being reactive with this antibody. Bovine SCO was also shown to synthesise mRNA encoding TTR under in vivo and in vitro conditions. We conclude that the SCO synthesises TTR and secretes it into the CSF. Colocalisation studies demonstrated that the SCO possessed two populations of secretory cells, one secreting both RF glycoproteins and TTR and the other secreting only the former. TTR was also detected in the SCO of bovine embryos suggesting that this ependymal gland is an important source of TTR during brain development.

The floor plate cells from bovines express the mRNA encoding for SCO-spondin and its translation products.

The floor plate (FP) is a transient structure of the embryonic central nervous system (CNS) which plays a key role in development driving cell differentiation and patterning in the ventral neural tube. The fact that antisera raised against subcommissural organ (SCO) secretion immunostain FP cells and react with high-molecular-mass proteins in FP extracts, prompted us to investigate the expression of a SCO-related polypeptide in FP cells. RNA from bovine FP was analyzed by means of reverse transcriptase polymerase chain reaction (RT-PCR), using primers derived from the 3' end of SCO-spondin which revealed products of 233, 237, 519 and 783 bp. Sequence analysis of the 233 bp PCR fragment confirmed the identity between this FP product and SCO-spondin. FP-translation of the SCO-spondin encoded polypeptide(s) was demonstrated by Western blot analysis and immunocytochemistry, using antisera raised against (i) the glycoproteins secreted by the bovine SCO, and (ii) a peptide derived from the open reading frame of the major SCO secretory protein, SCO-spondin, respectively. Additional evidence pointing to active transcription and translation of a SCO-spondin related gene was obtained in long term FP organ cultures. On the basis of partial sequence homologies of SCO-spondin with protein domains implicated in cell-cell contacts, cell-matrix interactions and neurite outgrowth it is possible to suggest that the SCO-spondin secreted by the FP is involved in CNS development.

Developmental expression of P0 mRNA and P0 protein in the sciatic nerve and the spinal nerve roots of the rat.

Expression of myelin P0 protein by myelinating Schwann cells in vivo is dependent on axonal influences. This report describes P0 gene expression during development of rat sciatic nerve and spinal nerve roots using Northern blotting, in situ hybridization and immunohistochemistry. We demonstrate that: (1) the appearance of P0 mRNA and P0 protein in Schwann cells during nerve development in the rat begins prenatally, at day 18 post-fertilization (E18); (2) P0 mRNA and P0 protein have essentially identical developmental profiles, and are expressed in Schwann cells that are many days prior to myelin formation; (3) initial P0 gene expression is greatest in Schwann cells at the periphery of nerve bundles and in Schwann cells in contact with motor axons; (4) the decline in P0 expression with nerve maturation is accompanied by a sharp decline in P0 message levels in most Schwann cells, but a small subpopulation of these cells continue to synthesize very high levels of P0 mRNA. This study provides data on myelin P0 protein gene expression and distribution during PNS development and adds further insights into the axonal influences controlling Schwann cell behaviour during myelination of the rat PNS.