Effects of orexins A and B on the secretory and proliferative activity of immature and regenerating rat adrenal glands.
Orexins A and B are two hypothalamic peptides, involved in the central regulation of feeding, which act through two receptor subtypes, named OX1R and OX2R. OX1R is 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 OX1R and OX2R mRNAs has been detected by reverse transcription-polymerase chain reaction in adult, immature and regenerating adrenals. Orexin-A increased corticosterone plasma concentration in immature rats, but not in animals with regenerating adrenals. Both orexins raised metaphase index (%o 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 OX1R and OX2R, respectively; and (2) do not affect secretion, but inhibit proliferative activity of regenerating adrenals, mainly via the activation of OX2R.
Malendowicz
L K
LK
Department of Histology and Embryology, School of Medicine, Poznan, Poland.
Jedrzejczak
N
N
Belloni
A S
AS
Trejter
M
M
Hochól
A
A
Nussdorfer
G G
GG
D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D002352:Carrier Proteins / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology; D064446:Orexin Receptors; D000068797:Orexins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide / Q000235:genetics; D012038:Regeneration / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002352:Carrier Proteins; C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D003345:Corticosterone