Biomedical subjects

M Marcinkiewicz

Publications and source records attributed to M Marcinkiewicz.

26 records · Page 2Linked to original sources

PubMed1986

Formation and maturation of axo-glandular synapses and concomitant changes in the target cells of the rat subcommissural organ.

Synapse formation and maturation in the subcommissural organ (SCO) of Wistar rats were studied from birth to the end of the first month. Modifications of the secretory ependyma were analyzed over the same period. On the 1st postnatal day, the large varicosities in contact with the SCO ependymocytes appeared immature (absence or low density of vesicular population, no synaptic membrane differentiation). The synaptic contacts were formed from the 3rd postnatal day, near the glandular cell nuclei (0.1 micron distance); progressively, the content of the axonal boutons and the pre- and post-synaptic specializations became similar to those of adults. From the 21st day on, the axo-glandular innervation was considered analogous to that in the adult. Using immunocytochemistry, it was found that the increase in the serotonin-immunoreactive fiber density in the whole organ was time-dependent. Light and electron microscopy demonstrated changes in the morphology of SCO ependymocytes during the first postnatal weeks, notably in the endoplasmic reticulum and content ot apical protrusions. On postnatal day 14, two types of ependymal cells, neonatal-like and adult-like, coexisted. The evolution of SCO ependymocytes coincided with the progressive onset and maturation of axo-glandular innervation taking place after birth.

Age Factors↗

PubMed1986

Quantitative autoradiography of multiple 5-HT1 receptor subtypes in the brain of control or 5,7-dihydroxytryptamine-treated rats.

The distribution of the 2 main types (A and B) of 5-HT1 binding sites in the rat brain was studied by light-microscopic quantitative autoradiography. The 5-HT1A sites were identified using 3H-8-hydroxy-2-(N-dipropylamino)tetralin (3H-8-OH-DPAT) or 3H-5-HT as the ligand. In the latter case, it was shown that 3H-5-HT binding to 5-HT1A sites corresponded to that displaceable by 0.1 microM 8-OH-DPAT or 1 microM spiperone. The "non-5-HT1A" sites labeled by 3H-5-HT in the presence of 0.1 microM 8-OH-DPAT corresponded mainly to 5-HT1B sites. 5-HT1A binding was notably high in limbic regions (dentate gyrus, CA1 and CA3 hippocampal regions, lateral septum, frontal cortex), whereas 5-HT1B binding was particularly concentrated in extrapyramidal areas (caudate nucleus, globus pallidus, substantia nigra). Except in the latter regions, where only one class of 5-HT1 sites was found, both 5-HT1A and 5-HT1B sites existed in all areas examined. The selective degeneration of serotoninergic neurons produced by an intracerebral injection of 5,7-dihydroxytryptamine was associated only with a significant loss of 5-HT1A binding to the dorsal raphe nucleus (-60%) and of 5-HT1B binding to the substantia nigra (-37%). These results are discussed in relation to the possible identity of 5-HT1A and/or 5-HT1B sites with the presynaptic 5-HT autoreceptors controlling nerve impulse flow and neurotransmitter release in serotoninergic neurons.

5,7-Dihydroxytryptamine↗

PubMed1985

Immunoreactivity of vasopressin and a novel pituitary protein '7B2' in Long-Evans and Brattleboro rat hypothalamus and hypophysis.

The unlabeled antibody (peroxidase-anti-peroxidase) method was used to simultaneously localize vasopressin and a novel pituitary protein designated '7B2' in rat hypothalamus and pituitary. Results showed the common localization of both substances within magnocellular neurons of supraoptic, supraoptic retrochiasmic and paraventricular nuclei. The distribution was also similar in the inner zone of the median eminence and in the posterior lobe of the pituitary gland. Only 7B2 antiserum labeled the external zone of the median eminence and the intermediate and anterior lobes of the pituitary. In the Brattleboro rat the anterior and intermediate lobes were strongly labeled with 7B2-IR and there was some 7B2-staining in the hypothalamus and the posterior lobe, but the intensity of the reaction was diminished.

Animals↗

PubMed1985

GAWK, a novel human pituitary polypeptide: isolation, immunocytochemical localization and complete amino acid sequence.

During the course of reverse-phase high pressure liquid chromatography (RP-HPLC) purification of a postulated big ACTH (1) from human pituitary gland extracts, a highly purified peptide bearing no resemblance to any known polypeptide was isolated. The complete sequence of this 74 amino acid polypeptide, called GAWK, has been determined. Search on a computer data bank on the possible homology to any known protein or fragment, using a mutation data matrix, failed to reveal any homology greater than 30%. An antibody produced against a synthetic fragment allowed us to detect several immunoreactive forms. The antisera also enabled us to localize the polypeptide, by immunocytochemistry, in the anterior lobe of the pituitary gland.

Amino Acid Sequence↗

PubMed1985

Immunocytochemical localization of a novel pituitary protein (7B2) within the rat brain and hypophysis.

A novel pituitary protein called 7B2 was localized in rat pituitary and brain by immunocytochemistry (unlabeled antibody technique). Immunoreactive material was present in the secretory cells of anterior and intermediate lobes and in neural structures of the posterior lobe of the hypophysis. 7B2-immunoreactive neurons were evident within the hypothalamus in the supraoptic nucleus, paraventricular nucleus (magnocellular and parvocellular parts), and lateral hypothalamus. Immunoreactive nerve fibers were seen within the internal and external zone of the median eminence. Among extrahypothalamic regions, the substantia nigra, dorsal tegmental nucleus, cuneiform nucleus, dorsal parabrachial nucleus, spinal tract trigeminal nerve, interior olive, solitary nucleus, and layers I and II of the spinal cord contained 7B2-immunoreactive material. This anatomical distribution suggests a role for 7B2 in endocrine and autonomic functions.

Aging↗

PubMed1984

Autoradiographic evidence for the heterogeneity of 5-HT1 sites in the rat brain.

The distribution of the binding sites of a new, potent agonist of serotonin (5-HT), 8-OH-N,N-dipropyl-2-aminotetralin (PAT), was studied in the rat brain with the quantitative autoradiographic technique utilizing tritium-sensitive LKB film. The localization of [3H]PAT binding sites was very similar to that of [3H]5-HT binding sites, except in some discrete regions (choroid plexus, striatum, area preoptica lateralis, subiculum, and substantia nigra), which exhibited very low levels of labeling with [3H]PAT and high levels with [3H]5-HT. These results indicate that 5-HT1 receptors are heterogeneous, and that [3H]PAT recognizes only a 5-HT1 subclass (called 5-HT1A).

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1983

The ependymal secretion of the fetal and adult rat subcommissural organ. morphological aspects linked to the synthesis, storage and release of the secretory products.

Different localizations of secretory material are noted in adult and fetal subcommissural organ (SCO) in light microscopy. At the electron microscope level, the secretory ependymocytes reveal frequent associations among mitochondria and ribosomes of the endoplasmic reticulum (ER). In the SCO ependymocytes of the adult rat, the relationship between mitochondria and ribosomes of the ER is observed in the subgolgian zone, the ER cisternal profiles are smooth except where they face the mitochondria. Here, a constant interval of 40-45 nm separates the ribosome-coated ER membrane from the external membrane of the mitochondria. This association evidences a functional cooperation between mitochondria and ER, at least in some phases of the synthesis of the organ's gliosecretory material. By contrast, in the fetus (17-21 fetal day), the synthetic apparatus displays an entirely granular ER. The secretory products are stored as flocculent material which fills the ER cisternae. In the apical zone of the ependymocytes, as the membrane of the dense secretory granules fuses with the apical plasmalemma, the granules release their contents into the ventricular cavity. A possible link between the releasing process and the coated vesicles is discussed.

Animals↗

PubMedDate not supplied

cDNA sequence of two distinct pituitary proteins homologous to Kex2 and furin gene products: tissue-specific mRNAs encoding candidates for pro-hormone processing proteinases.

Based on the concept of sequence conservation around the active sites of serine proteinases, polymerase chain reaction applied to mRNA amplification allowed us to obtain a 260-bp probe which was used to screen a mouse pituitary cDNA library. The primers used derived from the cDNA sequence of active sites Ser* and Asn* of human furin. Two cDNA sequences were obtained from a number of positive clones. These code for two similar but distinct structures (mPC1 and mPC2), each being homologous to yeast Kex2 and human furin. In situ hybridization (mPC1) and Northern blots (mPC1 = 3.0 kb and mPC2 = 2.8 and 4.8 kb) demonstrated tissue and cellular specificity of expression, only within endocrine and neuroendocrine cells. These data suggest that mPC1 and mPC2 represent prime candidates for tissue-specific pro-hormone converting proteinases.

Amino Acid Sequence↗