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.
Jankowski
Marek
M
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
Reis
Adelina M
AM
Wang
Donghao
D
Gutkowska
Jolanta
J
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