Effects of orexins A and B on the secretory and proliferative activity of immature and regenerating rat adrenal glands

• Malendowicz, L.K. ^[2] ; Jedrzejczak, N. ^[2] ; Belloni, A. S. ^[1] ; Tretjer, M. ^[2] ; Hochol, A. ^[2] ; Nussdorfer, G.G. ^[1]
  1. [1] University of Padua

     University of Padua

     Padova, Italia

     
  2. [2] Department of Histology and Embryology. School of Medicine, Poznan, Poland
• Localización: Histology and histopathology: cellular and molecular biology, ISSN-e 1699-5848, ISSN 0213-3911, Vol. 16, Nº. 3, 2001, págs. 713-717
• Idioma: inglés
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• Resumen

  • Orexins A and B are two hypothalamic peptides, involved in the central regulation of feeding, which act through two receptor subtypes, named OX} R and OX2R. OX1R i selective for orexin-A, and OX2R binds both orexins. We have investigated the effects of three subcutaneous injections of 10 nmol/kg body weight of orexins on the secretion and proliferative activity of immature (20-day-old) and regenerating rat adrenal cortex. The presence of both OX} Rand OX2R mRNAs has been detected by reverse transcriptionpolymerase chain reaction in adult, immature and regenerating adrenals. Orexin-A increased corticosterone plasma concentration in immature rat , but not in animals with regenerating adrenals. Both orexins raised metaphase index (%0 of metaphase-arrested cells) in immature rat adrenals, orexin-B being more effective than orexin-A. In contrast, both orexins equipotently lowered adrenal metaphase index at day 5 (but not day 8) of adrenal regeneration. We conclude that orexins (1) stimulate secretion and proliferative activity of immature rat adrenals, acting through OX 1 Rand OX2R, respectively; and (2) do not affect secretion, but inhibit proliferative activity of regenerating adrenals, mainly via the activation of OX2R.