Localization of endothelin-A and -B receptors during the postnatal development of rat cerebellum

Intense expression of mRNA of endothelin-B receptor (ETBR) has been detected in the Bergmann glia of cerebellum by in situ hybridization, but the intracellular localization has not been reported because of the absence of a useful antibody for immunohistochemical investigations. We made polyclonal antibodies against the carboxyl terminus of human ETBR (420-442) and ETAR (403-427), and performed light- and electron-microscopic immunohistochemistry of the wild-type and ETBR-deficient (sl/sl) rat cerebella. Localization of ETBR during postnatal development was examined by double-staining immunofluorescence using antibodies against ETBR and S-100 beta. In the wild-type rats, ETBR immunoreactivity appeared from postnatal day 5 (P5) and was distributed diffusely in the processes and cell bodies of S-100 beta-positive glial cells. By P14, ETBR immunoreactivity was concentrated in the Golgi apparatus of Bergmann glial cell soma and the plasma membrane of its processes. The ETBR-positive astrocytes in the granular layer decreased in number during P7-14 and had disappeared by week 3. At 3 weeks, ETBR immunoreactivity was restricted to the Golgi apparatus of Bergmann glia. In the sl/sl rats, ETBR immunoreactivity was not observed at all. In contrast to ETBR, ETAR immunoreactivity appeared transiently in the cytoplasm of all astrocytes (Bergmann glia and astrocytes in the granular layer) in the 9- to 14-day-old wild rats and 7- to 14-day-old sl/sl rats, and disappeared within 3 weeks in both. Granule cells did not express immunoreactivity for ETBR and ETAR from the neonatal stage to adulthood. Changes in the intracellular localization of ETBR and transient expression of ETAR may be correlated with the changes of glial functions and proliferation during postnatal development of rat cerebellum.     

Effects of deltamethrin on granule cell migration during postnatal development of rat cerebellum

Deltamethrin (DLT; 0.7mg/kg/body wt/day, i.p., dissolved in propylene glycol) administration during postnatal days 913 in Albino rat pups, resulted in a delayed appearance of radial glial fibers, that guide the migration of granule cells. Moreover, the radial glial fibers in the DLT-treated pups were disorganized, hypertrophied and heavily stained. Thus, it is being proposed that although after exposure to DLT the neuronal proliferation occurs at normal rate, the neuronal migration along the stumpy and crumpled radial fibers hamper the journey of the healthy neurons to their proper destination.     

Thyroxine effects on polyamine metabolism in rat cerebellum and brain cortex during postnatal development

Polyamine content, ODC and SAMDC activities have been assayed in cerebellum and brain cortex of hyperthyroid rats during postnatal development. Daily thyroxine treatment induced ODC and SAMDC biosynthesis in early periods of postnatal life in both cerebellum and brain cortex. In addition, in comparison to controls an increase in spermidine and spermine content was shown to occur in hyperthyroid rats. A functional correlation between polyamine content and nucleic acids could explain a correlation between polyamine biosynthesis and morphofunctional maturative processes in the brain.     

Synthesis of proteins in heart mitochondria during postnatal development of the rat

Proteins of inner mitochondrial membranes of the albino rat myocardium during postnatal development of 1, 3 and 6 months old animals were electrophoretically separated in 10% polyacrylamide gel. The rate of 14C-amino acids incorporation into examined proteins was determined in vitro. Specific radioactivity of the total mitochondrial fraction decreased in the course of the postnatal development. That of outer membranes remained unchanged, though it sharply increased in inner membranes of mature animals as compared with animals aged one month. Levels of radioactive precursor incorporation in separate protein fractions of inner membranes of the myocardium mitochondria were estimated.     

Compositional changes in soluble proteins of cerebral mantle,cerebellum, and brain stem of rat brain during development

Soluble proteins from the cerebral mantle, cerebellum, and brain stem of rat brains were analyzed at various developmental stages by a two-dimensional gel electrophoresis technique. The electrophoretic technique resolved the soluble proteins into 100–150 polypeptide spots on two-dimensional gels and gave reproducible and highly resolved profiles of them. Although most of major polypeptides were commonly found in all the three brain regions, some polypeptides were shown to be unique to a specific brain region. Each brain region was different in the electrophoretic profile of soluble proteins at every developmental stage examined, although there was considerable similarity in the profiles of each of the three brain regions in fetal animals (16–17 days), indicating that soluble proteins undergo different compositional changes in each of the three brain regions during postnatal development. In addition, the number of polypeptide spots on the electrophoretic profile increased remarkably during postnatal development in all of the three brain regions, suggesting that soluble proteins become more heterogeneous during postnatal development in each of the three brain regions.     

Neurotoxicological effects of deltamethrin on the postnatal development of cerebellum of rat

Deitamethrin (DLT) has been accepted to be 10,000 times less toxic to man than to insects. While toxicity of DLT in adult animals has been studied using biochemical and electrophysiological tools, reports on its developmental neurotoxicity are rather scanty. Wistar rat pups were exposed to DLT (0·7 mg/kg body wt/day, i.p., dissolved in propylene glycol from postnatal day 9–13. Equal number of age matched pups were used as vehicle controls. The animals were weighed and perfused intracardially on postnatal days 12,15,21, and 30 and their brains dissected out. Cerebellum along with the brainstem was separated by a transverse section at the tectal level and processed for morphometric and toxicological studies. The micro-and inter-neurons in the cerebellum are known to differentiate and mature, both morphologically and biochemically, during the postnatal life of rats. Postnatal exposure to DLT has been observed to delay the cytogenesis and morphogenesis of these neurons. In addition to this, damage to the developing vasculature has also been recorded in the form of thrombus and haemorrhage. Focal degeneration and spongy appearance of the tissue in the vicinity of the damaged blood vessels have also been recorded. The study has opened up several questions on the safety of this substance to the pregnant mothers and infants in the habitats where this substance is in use for vector control.     

Changes of mitochondrial membrane proteins in rat cerebellum during aging

Qualitative and quantitative changes of mitochondrial membrane proteind during aging were investigated. Free (non-synaptic) mitochondria were purified from rat cerebellum at different ages (4, 8, 12, 16, 20, and 24 months). Mitochondrial outer membrane (OM), inner membrane (IM) and matrix (MX) were separated and the proteins were extracted and analyzed by gel-electrophoresis.After staining, the gels were scanned densitometrically to quantify the proteins. No significant changes in the quantity of OM or MX protein subunits were observed, while serveral statistically significant quantitative changes in IM proteins with age were found. These age-dependent modifications of inner membrane mitochondrial proteins may play an important role in energy transduction, transport systems and regulatory enzymatic activities in mitochondria.     

Tectorial membrane changes in hypothyroid rats during postnatal development

The morphological changes of the tectorial membrane (TM) during the postnatal development (0, 3, 6, 12 and 25 day old) of the organ of Corti were studied by light microscopy in 20 control and hypothyroid rats. Hypothyroidism was induced by daily administration of propylthioruracil (PTU) until the end of lactation. The auditive receptor in the cochlea of the hypothyroid animals shows serious structural alterations compared with those of normal ones: abnormal persistence of K?lliker's organ, immaturity of sensory cells and supporting cells and a specific distortion of the TM. Differences with controls were first observed on the sixth postnatal day of the hypothyroid rats. The inner spiral sulcus was not shaped and the TM was attached to the K?lliker's organ. In older stages (12 and 25 days), K?lliker's organ was still present. The TM acquired a shap hump with an abnormal fibrillar arrangement in its middle part. It was still attached to the outer supporting cells by a remnant of the marginal net. It was suggested that the TM is secreted by the inner spiral limbus and K?lliker's organ. An abnormal persistence of these structures in the hypothyroidism results in a retardation of Corti's organ development. However, this conclusion does not explain the absence of the outer portion of the TM. Our study confirms the hypothesis that the secretion of any components of the marginal zone of TM is made by outer supporting cells which in PTU-treated animals appear very immature and with hypoplasia.     

Differential expression of porcine testis proteins during postnatal development

The development of the testes includes changes in cell morphology and endocrine levels that are essential for the maturation of males. A large number of novel proteins are expressed throughout testis development and play important roles in spermatogenesis. Differences in protein expressions during the development of porcine testes have not been systematically studied. The purpose of this study was to investigate differential protein expression in porcine testes during postnatal development. Testes from four pigs each at 1wk, 3mo, and 1yr of age were used for a proteomic analysis. Expression levels of 264 protein spots were quantified using the Melanie 3 software. In total, 108 protein spots showed more than 2-fold differences (P<0.05) among developmental stages, and 90 of them were successfully identified by mass spectrometry. The proteins were sorted based on whether the expression levels increased with age (36.1%), decreased with age (38.0%), or fluctuated among different developmental stages (25.9%). In total, 69 unique gene products were further classified according to their gene ontology annotations. A majority of the proteins are organelle proteins (41%) with the nucleus and mitochondria being the main organelles. About 45% of the proteins have a protein binding domain and are likely involved in protein-protein interactions. Finally, a large proportion of these differentially expressed proteins are involved in cellular (25%) and metabolic (22%) processes. Identifying these differentially expressed proteins should be valuable for exploring developmental biology and the pathology of male reproduction.     

Changes in the cerebellum of the rat after actinomycin during the postnatal period]

A single dose of actinomycin was applied to young Wistar albino rats in the critical phase of their cerebellar development. The morphological alterations of the cerebellar cortex were studied by means of light and electron microscopy on several postnatal days. The cell types of the cerebellar cortex reacted in different ways toward the noxious substance according to their stage of development. The acute alterations consisted of an edematous reaction of the neuronal and glial perikarya (light degeneration) and a shrinkage of the neurons (dark degeneration). A massive intercellular edema and a rarefaction of glia cells as well as the Purkinje cell fibres proved to be the long-term damage. This pattern of the alteration was discussed regarding the chemodifferentiation of the cells of the cerebellar cortex, the onset of cerebellar function on day 14, and the establishment of a neuroglial functional unit.     

Effect of hypothyroidism on the biogenesis of free mitochondria in the cerebral hemispheres and in cerebellum of rat during postnatal development

The effect of propylthiouracil-induced neonatal hypothyroidism on some aspects of the biogenesis of free (non-synaptosomal) mitochondria in the cerebral hemispheres and in the cerebellum of developing rat has been studied. The results obtained show that in hypothyroid rats mitochondrial DNA synthesis is delayed, mitochondrial RNA synthesis is not affected and cytochrome aa₃ content of mitochondria is lower than in controls. Furthermore ultrathin sections of 14-and 21-day old hypothyroid rat cerebella show mitochondria with an altered ultrastructural organization and large intracristal spaces.     

Polysomes during early postnatal development of brain in the rat

We have attempted to show eventual modifications in the brain protein synthesis apparatus of rat during the first three weeks after birth. Through this time we noted a steady decrease (about 60%) in the free polysomes, when expressed relative to tissue weight. This decrease does not correlate with changes in the polysome profile, indicating that no loss in the efficiency of protein synthesis was involved. Translation in a reticulocyte lysate also failed to reveal differences.     

Ontogenesis of alpha-amylase in rat parotid gland during postnatal development

Changes in alpha-amylase (alpha-1,4-glucan-4-glucanohydrolase, EC 3.2.1.1) of parotid gland were investigated during postnatal development of the rat. Modifications in amylase activity after birth allow the distinction of three stages which can be correlated with the morphologic development of the parotid gland. Significant sexual differences in the evolution of alpha-amylase activity were found. During the first stage (from birth to the 20th day) there is a higher increase in females, while males have a more pronounced increment in the second stage (from the 20th to the 30th day). By means of gel electrophoresis of parotid extracts, four molecular forms of amylase can be separated. The slowest migrating band (Form 1) is not detected at the initial stage.     

Ontogenesis of alpha-amylase in rat parotid gland during postnatal development

Summary Changes in -amylase (-1,4-glucan-4-glucanohydrolase, EC 3.2.1.1) of parotid gland were investigated during postnatal development of the rat. Modifications in amylase activity after birth allow the distinction of three stages which can be correlated with the morphologic development of the parotid gland. Significant sexual differences in the evolution of -amylase activity were found. During the first stage (from birth to the 20th day) there is a higher increase in females, while males have a more pronounced increment in the second stage (from the 20th to the 30th day). By means of gel electrophoresis of parotid extracts, four molecular forms of amylase can be separated. The slowest migrating band (Form 1) is not detected at the initial stage.Career scientist of the Consejo Nacional de Investigaciones Científicas y Téchnicas of Argentina