RESUMO
The thyroid-stimulating hormone/thyrotropin (TSH) is the most relevant hormone in the control of thyroid gland physiology in adulthood. TSH effects on the thyroid gland are mediated by the interaction with a specific TSH receptor (TSHR). We studied the role of TSHTSHR signaling on gland morphogenesis and differentiation in the mouse embryo using mouse lines deprived either of TSH (pit(dw)pit(dw)) or of a functional TSHR (tshr(hyt)tshr(hyt) and TSHR-knockout lines). The results reported here show that in the absence of either TSH or a functional TSHR, the thyroid gland develops to a normal size, whereas the expression of thyroperoxidase and the sodium/iodide symporter are reduced greatly. Conversely, no relevant changes are detected in the amounts of thyroglobulin and the thyroid-enriched transcription factors TTF-1, TTF-2, and Pax8. These data suggest that the major role of the TSH/TSHR pathway is in controlling genes involved in iodide metabolism such as sodium/iodide symporter and thyroperoxidase. Furthermore, our data indicate that in embryonic life TSH does not play an equivalent role in controlling gland growth as in the adult thyroid.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Receptores da Tireotropina/fisiologia , Transdução de Sinais/fisiologia , Glândula Tireoide/embriologia , Tireotropina/fisiologia , Animais , Antígenos de Diferenciação/biossíntese , Antígenos de Diferenciação/genética , Diferenciação Celular , Cruzamentos Genéticos , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Fatores de Transcrição Forkhead , Idade Gestacional , Humanos , Hipotireoidismo/embriologia , Hipotireoidismo/genética , Iodeto Peroxidase/biossíntese , Iodeto Peroxidase/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Morfogênese , Proteínas Nucleares/biossíntese , Proteínas Nucleares/genética , Tamanho do Órgão , Fator de Transcrição PAX8 , Fatores de Transcrição Box Pareados , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptores da Tireotropina/deficiência , Receptores da Tireotropina/genética , Proteínas Recombinantes de Fusão/fisiologia , Proteínas Repressoras/biossíntese , Proteínas Repressoras/genética , Simportadores/biossíntese , Simportadores/genética , Tireoglobulina/biossíntese , Tireoglobulina/genética , Glândula Tireoide/crescimento & desenvolvimento , Glândula Tireoide/patologia , Fator Nuclear 1 de Tireoide , Tireotropina/deficiência , Tireotropina/genética , Transativadores/biossíntese , Transativadores/genética , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genéticaRESUMO
Pituitary adenylate cyclase-activating peptide (PACAP) is a novel vasoactive intestinal peptide (VIP)-like peptide isolated from ovine hypothalamus. It is present in neuronal elements of a number of peripheral organs. We have examined whether PACAP occurs in the gill arch of Carassius auratus L. in which our recent studies have shown the presence of VIP-like peptide. Immunohistochemistry has revealed PACAP-like immunoreactivity in the anterior branches of the post-trematic glossopharyngeal and vagus nerves. PACAP-immunoreactive nerve cell bodies and fibers are present in connective tissue on the oral side of the gill arch. Colocalization studies carried out by the application of double immunofluorescence show that a PACAP-like peptide coexists with VIP in the same nerve cell bodies and fibers. The localization pattern of PACAP in the gill arch of goldfish suggests its possible involvement in the regulation of secretory activities.
Assuntos
Brânquias/metabolismo , Carpa Dourada/metabolismo , Neuropeptídeos/metabolismo , Neurotransmissores/metabolismo , Peptídeo Intestinal Vasoativo/metabolismo , Animais , Brânquias/inervação , Nervo Glossofaríngeo/metabolismo , Imuno-Histoquímica , Inclusão em Parafina , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase , Nervo Vago/metabolismoRESUMO
The localization of vasoactive intestinal polypeptide (VIP)-immunoreactive (ir) nerve cell bodies and fibers has been studied in the gill arches of goldfish (Carassius auratus, L.) using the peroxidase-antiperoxidase (PAP) immunohistochemical method. It was found that VIP-ir nerve cell bodies are localized in connective tissue on the oral side of the gill arch; these cells were present as single cells, in couples or as small clusters. Moreover, a dense network of VIP-ir fibers was observed beneath the lining epithelium of the raker cushion. The possible involvement of this peptide in mucus secretion in the gill arches of teleost is discussed.
