Arginin-vasopressin regulates proliferative activity of the regenerating rat adrenal cortex.
Enucleation-induced adrenal regeneration is a classic model to investigate adrenocortical proliferation in vivo, which is dependent not only on pituitary ACTH release, but also on various other neural and endocrine signals. Arginin-vasopressin (AVP), mainly acting via V1 receptors, regulates hypothalamic-hypophyseal-adrenal axis function, acting on both its central and peripheral branches. Here, we studied whether endogenous AVP system modulates rat adrenal regeneration. Reverse transcription-polymerase chain reaction (PCR) detected only the mRNAs of V1a and V1b receptors in normal and regenerating adrenals. The expression was very low, and semi-quantitative conventional and real-time PCR showed that it was down-regulated in regenerating adrenals in relation to the time elapsed from enucleation. AVP (three subcutaneous injections 28, 16 and 4 h before sacrifice) raised metaphase index at day 5, but not at day 8 of regeneration. Unexpectedly, both V1-receptor and V2-receptor antagonists increased metaphase index at days 5 and 8 of regeneration. Neither AVP nor AVP-receptor antagonists affected plasma levels of corticosterone in rats bearing regenerating adrenals. It is concluded that AVP, acting via V1 receptors located in adrenals, exerts a stimulating effects on adrenal regeneration. Due to the down-regulation of V1-receptor expression in regenerating adrenals, this effect is very weak and is easily overcome by a tonic inhibitory action of endogenous AVP systems probably involving extra-adrenal indirect mechanisms.
Trejter
Marcin
M
Department of Histology and Embryology, School of Medicine, Karol Marcinkowska University of Medical Sciences, PL-60781 Poznan, Poland.
Carraro
Gianni
G
Rucinski
Marcin
M
Hochol
Anna
A
Rebuffat
Piera
P
Nussdorfer
Gastone G
GG
Malendowicz
Ludwik K
LK
D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects*; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D015536:Down-Regulation; D005260:Female; D005786:Gene Expression Regulation; D008677:Metaphase; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017483:Receptors, Vasopressin / Q000378:metabolism*; D012038:Regeneration / Q000187:drug effects / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D012333:RNA, Messenger; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D003345:Corticosterone