Cultured rat calvarial osteoblast-like cells are provided with orexin type 1 receptors.
Orexins A and B are hypothalamic peptides which are derived from the proteolytic cleavage of prepro-orexin and act via two subtypes of receptors, named OX1-R (that almost exclusively binds orexin-A) and OX2-R (nonselective for both orexins). Several lines of evidence show that other neuropeptides, which like orexins are involved in the central control of energy homeostasis (e.g. leptin and ghrelin), may play a role in the regulation of bone metabolism, acting via autocrine-paracrine or endocrine routes. Therefore, we studied by reverse transcription-polymerase chain reaction (RT-PCR) the expression of the orexin system in rat calvarial osteoblast-like (ROB) cells, whose osteoblastic lineage was immunocytochemically demonstrated by their osteonectin and collagen-1alpha content at day 14 of culture. Conventional PCR detected the mRNA expression of OX1-R, but not OX2-R and prepro-orexin in ROB cells at days 2, 7 and 21 of culture. Semiquantitative real time-PCR evidenced a gradual down-regulation of OX1-R mRNA in relation to the duration of culture. This novel finding suggests that rat osteoblasts could be a target for circulating orexin-A, especially during their early stages of differentiation into mature osteoblasts.
Ziolkowska
Agnieszka
A
Department of Histology and Embryology, School of Medicine, Karol Marcinkowski University of Medical Sciences, PL-60781 Poznan, Poland.
Rucinski
Marcin
M
Tortorella
Cinzia
C
Tyczewska
Marianna
M
Nussdorfer
Gastone G
GG
Malendowicz
Ludwik K
LK
D000818:Animals; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism; D064446:Orexin Receptors; D000068797:Orexins; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D015676:Osteonectin / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism*; D012886:Skull / Q000166:cytology*
D024042:Collagen Type I; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D015676:Osteonectin; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide