A központi idegrendszeri pajzsmirigyhormon aktiváció szabályozásának molekuláris biológiája = Molecular biology of the regulation of thyroid hormone activation in the central nervous system

A pajzsmirigyhormonok számos biológiai folyamat, így a fejlődés, a növekedés és az anyagcsere alapvető fontosságú tényezői. A tiroxin (T4) pro-hormon, melynek a pajzsmirigyhormon aktiváció során dejodációval T3-á kell alakulnia ahhoz, hogy a pajzsmirigyhormon magreceptorhoz kötődve biológiai hatásait kifejthesse. A T4 aktivációt az agyban a kettes-típusú dejodáz enzim (D2) katalizálja. A pályázat célkitűzései a központi idegrendszeri pajzsmirigyhormon aktiváció celluláris és molekuláris vonatkozásainak vizsgálatához kapcsolódtak. Az alacsony T3 szindróma molekuláris pathogenezisének vizsgálata során feltártuk az emberi dio2 gén NF-kB érzékenységét és leírtuk annak molekuláris hátterét. Jellemeztük a D2 fehérje ubikvitinációjában kulcsszerepet játszó fehérjék idegrendszeri eloszlását, továbbá a D2 enzim poszt-transzlációs szabályozásának szubcelluláris és konformációs feltételeit. Vizsgálataink során tanulmányoztuk a T3 képződés mechanizmusát a fejlődő idegrendszerben és kimutattuk a D2 expresszió megjelenését a fejlődő hipotalamusz tanicitáiban. Munkánk az idegrendszeri T3 függő génexpressziós profilok kialakulásért felelős szabályozó mechanizmusok feltérképezése révén járul hozzá a fejlődő és kifejlett agy működését befolyásoló tényezők jobb megértéséhez. | Thyroid hormone is a crucial factor of development, growth and metabolism. The pro-hormone thyroxine (T4) has to be converted to T3 via thyroid hormone activation in order to bind the thyroid hormone receptor to modulate thyroid hormone dependent pathways. Local T3 generation in the adult and developing brain is catalyzed by the type 2 deiodinase selenoenzyme (D2). The aim of the project was to better understand the cellular and molecular events underlying thyroid hormone activation in the central nervous system. We studied the molecular pathogenesis of the low T3 syndrome and described the molecular components ensuring NF-kB mediated induction of the human dio2 gene. We characterized the distribution of key proteins of D2 ubiquitination in the brain and determined the subcellular and conformational requirements of post-translational regulation of the D2 enzyme. We studied the mechanisms of T3 generation in the developing brain and determined the developmental expression of D2 in hypothalamic tanycytes. Our data contribute to the better understanding of factors regulating the function of the developing and adult brain via providing a deeper insight into mechanisms generating T3 dependent gene expression profiles

Glycinergic input to the mouse basal forebrain cholinergic neurons

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Interleukin-1 receptor type 1 is over-expressed in neurons but not in glial cells within the rat superficial spinal dorsal horn in complete Freund adjuvant induced inflammatory pain

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GnRH Neurons Provide Direct Input to Hypothalamic Tyrosine Hydroxylase Immunoreactive Neurons Which Is Maintained During Lactation

Gonadotropin releasing hormone (GnRH) neurons provide neuronal input to the preoptic area (POA) and the arcuate nucleus (Arc), two regions involved critically in the regulation of neuroendocrine functions and associated behaviors. These areas contain tyrosine hydroxylase immunoreactive (TH-IR) neurons, which play location-specific roles in the neuroendocrine control of both the luteinizing hormone and prolactin secretion, as well as, sexually motivated behaviors. Concerning changes in the activity of GnRH neurons and the secretion pattern of GnRH seen under the influence of rising serum estrogen levels and during lactation, we tested the hypothesis that the functional state of GnRH neurons is mediated via direct synaptic connections to TH-IR neurons in the POA and Arc. In addition, we examined putative changes of these inputs in lactating mice and in mothers separated from their pups. Confocal microscopic and pre-embedding immunohistochemical studies on ovariectomized mice treated with 17β-estradiol (OVX+E2) provided evidence for direct appositions and asymmetric synapses between GnRH-IR fiber varicosities and TH-IR neurons in the POA and the Arc. As TH co-localizes with kisspeptin (KP) in the POA, confocal microscopic analysis was continued on sections additionally labeled for KP. The TH-IR neurons showed a lower level of co-labeling for KP in lactating mice compared to OVX+E2 mice (16.1 ± 5% vs. 57.8 ± 4.3%). Removing the pups for 24 h did not alter significantly the KP production in TH-IR neurons (17.3 ± 4.6%). The mean number of GnRH-IR varicosities on preoptic and arcuate TH cells did not differ in the three animal models investigated. This study shows evidence that GnRH neurons provide direct synaptic inputs to POA and Arc dopaminergic neurons. The scale of anatomical connectivity with these target cells was unaltered during lactation indicating a maintained GnRH input, inspite of the altered hormonal condition

A Novel Pathway Regulates Thyroid Hormone Availability in Rat and Human Hypothalamic Neurosecretory Neurons

Hypothalamic neurosecretory systems are fundamental regulatory circuits influenced by thyroid hormone. Monocarboxylate-transporter-8 (MCT8)-mediated uptake of thyroid hormone followed by type 3 deiodinase (D3)-catalyzed inactivation represent limiting regulatory factors of neuronal T3 availability. In the present study we addressed the localization and subcellular distribution of D3 and MCT8 in neurosecretory neurons and addressed D3 function in their axons. Intense D3-immunoreactivity was observed in axon varicosities in the external zone of the rat median eminence and the neurohaemal zone of the human infundibulum containing axon terminals of hypophysiotropic parvocellular neurons. Immuno-electronmicroscopy localized D3 to dense-core vesicles in hypophysiotropic axon varicosities. N-STORM-superresolution-microscopy detected the active center containing C-terminus of D3 at the outer surface of these organelles. Double-labeling immunofluorescent confocal microscopy revealed that D3 is present in the majority of GnRH, CRH and GHRH axons but only in a minority of TRH axons, while absent from somatostatin-containing neurons. Bimolecular-Fluorescence-Complementation identified D3 homodimers, a prerequisite for D3 activity, in processes of GT1-7 cells. Furthermore, T3-inducible D3 catalytic activity was detected in the rat median eminence. Triple-labeling immunofluorescence and immuno-electronmicroscopy revealed the presence of MCT8 on the surface of the vast majority of all types of hypophysiotropic terminals. The presence of MCT8 was also demonstrated on the axon terminals in the neurohaemal zone of the human infundibulum. The unexpected role of hypophysiotropic axons in fine-tuned regulation of T3 availability in these cells via MCT8-mediated transport and D3-catalyzed inactivation may represent a novel regulatory core mechanism for metabolism, growth, stress and reproduction in rodents and humans

Gén expresszió vizsgálatra fájdalommodellben TacMan Low Density Array segítségével

Mindkét fájdalom modellben azt tapasztaltuk, hogy a kemokineknek és citokineknek központi szerepe lehet fájdalom állapotban. Ezen mediátorok fájdalom során hamar felszabadulnak, és számos más faktor expresszióját modulálják.Mag