TY - JOUR
T1 - Prostaglandin F(2α) induces a rapid decline in progesterone production and steroidogenic acute regulatory protein expression in isolated rat corpus luteum without altering messenger ribonucleic acid expression
AU - Fiedler, Eric P.
AU - Plouffe, Leo
AU - Hales, Dale B.
AU - Hales, Karen H.
AU - Khan, Iqbal
PY - 1999
Y1 - 1999
N2 - With interest in steroidogenic acute regulatory protein (STAR) involvement in the luteolytic process, we studied changes in serum progesterone levels and the concomitant expression of StAR mRNA and protein (37-, 32-, and 30-kDa forms) in postovulatory Day 7 corpora lutea (CL) isolated from rats 1 h after injection with prostaglandin F(2α) (PGF(2α), n = 6) or saline (n = 6). Serum progesterone levels were determined by RIA, StAR and β-actin mRNA expression by Northern analysis, and StAR and β-actin protein expression by Western analysis. Adrenal, brain, and spleen from control animals were used as positive and negative controls for StAR expression. Scanning optical demitometry measurements were standardized by dividing the signal strength from each StAR autoradiogram lane by that from the corresponding β-actin autoradiogram lane. ANOVA was used for significance testing, with α set at 0.05. The 37-, 32-, and 30-kDa forms of StAR protein were expressed in all adrenal samples, whereas only the 37- and 30-kDa forms were found in CL. Serum progesterone levels and expression of the 30-kDa and 37-kDa forms of the StAR protein in CL were all found to be significantly lower in the PGF(2α)-treated than the saline-treated group. STAR mRNA expression was not significantly different in the saline- and PGF(2α)-treated rats. The rapid decline in StAR protein expression that accompanies PGF(2α) induced luteolysis, therefore, does not result from significant decline in mRNA expression.
AB - With interest in steroidogenic acute regulatory protein (STAR) involvement in the luteolytic process, we studied changes in serum progesterone levels and the concomitant expression of StAR mRNA and protein (37-, 32-, and 30-kDa forms) in postovulatory Day 7 corpora lutea (CL) isolated from rats 1 h after injection with prostaglandin F(2α) (PGF(2α), n = 6) or saline (n = 6). Serum progesterone levels were determined by RIA, StAR and β-actin mRNA expression by Northern analysis, and StAR and β-actin protein expression by Western analysis. Adrenal, brain, and spleen from control animals were used as positive and negative controls for StAR expression. Scanning optical demitometry measurements were standardized by dividing the signal strength from each StAR autoradiogram lane by that from the corresponding β-actin autoradiogram lane. ANOVA was used for significance testing, with α set at 0.05. The 37-, 32-, and 30-kDa forms of StAR protein were expressed in all adrenal samples, whereas only the 37- and 30-kDa forms were found in CL. Serum progesterone levels and expression of the 30-kDa and 37-kDa forms of the StAR protein in CL were all found to be significantly lower in the PGF(2α)-treated than the saline-treated group. STAR mRNA expression was not significantly different in the saline- and PGF(2α)-treated rats. The rapid decline in StAR protein expression that accompanies PGF(2α) induced luteolysis, therefore, does not result from significant decline in mRNA expression.
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U2 - 10.1095/biolreprod61.3.643
DO - 10.1095/biolreprod61.3.643
M3 - Article
C2 - 10456840
AN - SCOPUS:0032588665
SN - 0006-3363
VL - 61
SP - 643
EP - 650
JO - Biology of reproduction
JF - Biology of reproduction
IS - 3
ER -