Biomedical subjects

M Hadjiyiassemis

Publications and source records attributed to M Hadjiyiassemis.

4 recordsLinked to original sources

PubMed2004

Expression of the secreted FAD-dependent sulfydryl oxidase (QSOX) in the guinea pig central nervous system.

cpQSOx1 is a member of the QSOx family of proteins, expressed in the guinea pig (Cavia porcellus) and ortholog of the rat rQSOx1. In this study, in vitro experiments were conducted and showed that, as other member of this family, cpQSOx1 has a sulfydryl oxidase activity, and is a secreted protein. Then, the expression of this enzyme was researched in the guinea pig brain, as very little information exists yet on the expression of QSOx family members in the central nervous system. By immunohistochemistry, RT-PCR and in situ hybridization, cpQSOx1 is synthesized by neurons throughout the whole guinea pig central nervous system. Reticular structures as the basal forebrain, reticular thalamic nucleus and reticular nuclei of the brainstem contained the densest labeling. These results are discussed in terms of putative roles of this protein in synaptic strengthening and in redox activities.

Animals↗

PubMed1984

Corticoliberin neurons: cytophysiology, phylogeny and ontogeny.

In the rat hypothalamus, antibodies to ovine CRF41 stain neurons of a paraventriculo-infundibular neuroglandular pathway. CRF like immunoreactivity (CLI)-containing perikarya are mostly packed in the parvocellular division of the paraventricular nucleus. Their morphology and topography differ from that of other peptidergic neurons. However a few CLI perikarya are also stained with vasopressin antibodies. CLI neurons project massively to the external layer of the median eminence (ELME). Adrenalectomy induced a total depletion of ELME CLI 12 to 24 h after surgery, followed by a secondary accumulation already conspicuous 5 days later. This biphasic evolution, identical to that of ELME vasopressin, is totally prevented by a replacement therapy with dexamethasone. Reserpine also induces an acute depletion of ELME CLI and vasopressin, that can be prevented by a monoamine oxidase inhibitor pretreatment. These results indicate the involvement of CLI neurons in the corticotropic axis, suggesting that they are indeed corticoliberin neurons. Among the extrahypothalamic locations of CLI neurons their abundance in the amygdala central nucleus is of interest since it is involved in the corticotropic axis. A similar pattern of CLI was noticed in several mammalian brains and also in lower vertebrates (birds, reptiles, amphibians, fishes). Species adaptations of CLI neurons were observed: CLI neurons are of the cerebrospinal fluid contacting type in the turtle. CLI fibres terminate close to corticotrophs in the fish pituitary. This suggests a direct excitosecretory role of CRF on these cells and concurs with a CRF function of CLI peptide even in fishes. CLI processes and terminals appear in the human fetal ELME at the 16th week of development and increase in number during the following weeks. Perikarya are seen at 19 weeks. In the rat CLI fibers and perikarya were detected as early as the 18th day of fetal development. Thus, paraventriculo-infundibular CLI system develops later than corticotrophs. This chronology perfectly concurs with the results of previous physiological and experimental studies.

Adrenalectomy↗

PubMed1984

The CRF neuron: immunocytochemical study.

In the central nervous systems of several species belonging to different vertebrate classes, immunocytochemical stainings with an antiserum to ovine CRF 41 show multiple location of CRF perikarya and various areas containing CRF fibres and terminals. These stainings reflect species and interspecies functional adaptations of the CRF neurones which constitute a prominent hypothalamo-infundibular system involved in pituitary gland control, and also interneurone systems as attested to by extrahypothalamic perikarya and by CRF perisomatal endings in several brain areas. Perikarya of the hypothalamo-infundibular system are mainly packed in the paraventricular nucleus (mammals, birds) or in homologous areas, e.g.: paraventricular organ (turtle) where they are CSF-contacting neurones and preoptic nucleus (amphibians, fishes). In all species but fish, CRF fibres end in the median eminence (ME) against portal vessels. In fish, CRF processes terminate in the peripheral areas of proadenohypophyseal neurodigitations, close to corticotrophs. In all species these stainings are abolished by preabsorption of the serum by CRF. In fishes, reptiles and amphibians they are also suppressed by urotensin I, which is thought to be the teleost's CRF. Adrenalectomy experiments in the rat provided evidence for a corticosteroid regulation of ME CRF: short term (12-24 hr) adrenalectomy induces a complete depletion of CRF immunoreactivity followed by a secondary accumulation (5-20 days). This biphasic evolution is prevented by a dexamethasone replacement therapy. Inhibitory role of catecholamines on CRF release was indicated by: disappearance of ME CRF, induced by a single reserpine injection and suppression of this effect by monoamineoxidase inhibitor (pargyline or tranylcypromine) pretreatment. CRF fibres were first observed in the ME at the 16th week of fetal development in the human, and at the 18th day in the rat fetus. Thus, immunoreactive CRF system develops later than pituitary corticotrophs.

Adrenalectomy↗

PubMed1983

Reserpine-induced depletion of corticoliberin (CRF)-like immunoreactivity in the zona externa of the rat median eminence.

An acute reserpine treatment has the same selective and marked depleting effect on corticoliberin-like immunoreactivity as on vasopressin-like immunoreactivity in the rat zona externa of the median eminence. Somatostatin and gonadoliberin immunoreactivities appear unmodified. Reserpine effect is blocked by pretreatment with monoamine oxidase inhibitors (pargyline or tranylcypromine). Present results support the notion of an inhibitory role of monoamines, particularly catecholamines, on the release of corticoliberin.

Animals↗