ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Metabolic events stimulated by epinephrine and norepinephrine in hepatocytes isolated from fetal and early postnatal male rats are largely mediated through the β2-adrenergic receptor-/cyclic AMP dependent-system, whereas the same stimuli are transduced through the α1-adrenergic receptor-/phosphatidylinositol dependent-system in hepatocytes isolated from young adult male rats. This developmental transition was investigated by correlating hepatic α1- and β2-adrenergic receptor gene transcript levels with receptor levels as determined with selective radioligands in livers from late fetal to postnatal day 120 male Sprague-Dawley rats. β2-Adrenergic receptor concentration, initially high in membrane preparations isolated from fetal livers (203 ± 21 fmol/mg protein), dropped precipitously n postnatal day 6 livers (14± 2 fmol/mg protein) and remained low throughout development out to postnatal day 90.β-Adrenergic receptor mRNA levels were highest in fetal livers, were decreased somewhat in postnatal day 6 livers and were uncetectable in livers beyond postnatal day 15. In contrast, hepatic α-adrenergic receptor concentration was relatively low in fetal livers (86 ± 25 fmol/mg protein) and remained low until postnatal day 18. Thereafter, a steady increase in α1-adrenergic receptors was observed until adult levels. (270 ± 24 fmol/mg protein) were achieved at postnatal day 27. α1-Adrenergic receptor mRNA levels increased ∼ 3-fold, reaching a peak at postnatal day 24. Surprisingly, at postnatal day 30 hepatic α1-adrenergic receptor mRNA levels dropped to fetal levels; but, gradually increased with continued development. Thus, hepatic α1- and β2-adrenergic receptors appear to be under complex regulatory control which may include transcriptional, as well as post-transcriptional, mechanisms.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1041470108
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