Relationship between adenosine 3',5'-cyclic monophosphate level, cell proliferation, and alpha-amylase in rat parotid.
Treatment of rats with isoproterenol (IPR, beta 1- and beta 2-agonist), dobutamine (beta 1-agonist), and terbutaline (beta 2-agonist) increased the cAMP level and cell proliferation, but it decreased alpha-amylase activity in parotid glands. Terbutaline was relatively less effective. Alpha-Amylase activity as determined by substrate hydrolysis was maximally depressed (85% of control) after 15 min of IPR treatment; however, alpha-amylase level as determined by Western immunoblotting with the primary antibody to alpha-amylase decreased maximally after 2 h of treatment. The level of alpha-amylase significantly decreased after 15 min of treatment, but the levels of alpha-amylase mRNAs of 702 and 1176 base pairs (bp) slightly increased at this time. This suggests that an increased rate of transcription or a decreased rate of degradation of alpha-amylase mRNAs without a proportional increase in the rate of translation of alpha-amylase occurs in parotid glands after treatment with IPR. The levels of alpha-amylase mRNAs decreased after 2 h of treatment; however, the level of alpha-mRNA of 702 bp continued to decline, but the level of alpha-mRNA of 1176 bp increased at 3 days after IPR treatment. The level of actin mRNA of 2200 bp increased at 15 min and remained elevated during the entire observation period. Results showed that IPR-induced elevation of cAMP increases cell proliferation, and alters the level and activity of alpha-amylase and the expression of alpha-amylase genes at different rates.
Prasad
K N
KN
Center for Vitamins and Cancer Research, School of Medicine, University of Colorado Health Sciences Center, Denver 80262-0278.
Carvalho
E
E
Kumar
S
S
Edwards-Prasad
J
J
La Rosa
F G
FG
D000199:Actins / Q000235:genetics; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism*; D004280:Dobutamine / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013726:Terbutaline / Q000494:pharmacology; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D000318:Adrenergic beta-Agonists; D012333:RNA, Messenger; D004280:Dobutamine; D000242:Cyclic AMP; D000516:alpha-Amylases; D007545:Isoproterenol; D013726:Terbutaline