Postnatal ontogeny of natriuretic peptide systems in the rat hypothalamus.
Our study has attempted to clarify the developmental profile of atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) along with the expression of their receptors in the rat hypothalamus. Radioimmunoassay (RIA) of dissected hypothalamic tissue revealed that ANP rose from 167 +/- 50 pg/mg protein immediately after birth to 516 +/- 78 pg/mg protein in the next 24 h and to 928 +/- 100 pg/mg protein by postnatal day (PD) 5. A second increment of ANP in the hypothalamus was noted between PD 10 and PD 20 (from 780 +/- 110 to 2,650 +/- 136 pg/mg protein). These changes were not gender-related and consistent with a rise of ANP mRNA. Diethylstilbestrol treatment of immature rats increased hypothalamic ANP concentration from 2.11 +/- 0.24 to 2.97 +/- 0.44 ng/mg protein (P<0.001), but equine chorionic gonadotropin had no effect, indicating that estrogen is a potential stimulus of ANP only at supra-physiological concentrations. CNP, the most abundant natriuretic peptide in the brain, gradually increased in the developing hypothalamus, but did not plateau at PD 20. Reverse transcription-polymerase chain reaction analysis of ANP receptor mRNA demonstrated higher guanylyl cyclase (GC) A, no changes in GC-B, and lower C-receptor levels in adult compared to newborn rats. In conclusion, we have shown that hypothalamic ANP undergoes a dramatic rise after birth, and progresses further until the 3rd postnatal week. ANP and CNP changes in the developing hypothalamus can influence brain maturation.
Centre de recherche, Centre hospitalier de l'Université de Montreal-Hôtel-Dieu, Pavillon de Bullion, 3850 rue Saint-Urbain, Montreal, Quebec H2W 1T7, Canada. marek.jankowski@umontreal.ca
Marek
M
Jankowski
Adelina M
AM
Reis
Donghao
D
Wang
Jolanta
J
Gutkowska
D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D006062:Gonadotropins / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000187:drug effects / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D008297:Male; D020098:Natriuretic Peptide, C-Type / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D004967:Estrogens; D006062:Gonadotropins; D012333:RNA, Messenger; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C