Evidence for regulation of tyrosine hydroxylase mRNA translation by stress in rat adrenal medulla.
Long-term stress leads to the induction of tyrosine hydroxylase (TH) protein and enzymatic activity in the adrenal medulla. This adaptive response is necessary to maintain the catecholamine biosynthetic capacity of adrenal chromaffin cells during periods of sustained catecholamine secretion. In this report we demonstrate that when rats are subjected to short-term stress, TH mRNA is induced for at least 24 h, but TH protein and TH activity (assayed under Vmax conditions) are not increased. In contrast, adrenal TH mRNA, TH protein and TH activity are induced in rats subjected to long-term stress. Using sucrose gradient fractionation, we show that the lack of induction of TH protein after one type of short-term stressor, a single 2-h immobilization stress is associated with a decrease in the percentage of TH mRNA molecules associated with polysomes. In contrast, after repeated immobilizations the polysome profile of TH mRNA is identical to that observed in control animals, even though TH mRNA is induced 2- to 3-fold. These results are consistent with the hypothesis that even though TH mRNA is induced by short-term stressors, mechanisms that control TH mRNA translation must also be appropriately regulated for TH protein to be induced.
Xu
Lu
L
Department of Pharmacology and Physiology, Box 711 University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
Chen
Xiqun
X
Sun
Baoyong
B
Sterling
Carol
C
Tank
A William
AW
D000313:Adrenal Medulla / Q000201:enzymology*; D000704:Analysis of Variance; D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D003080:Cold Temperature / Q000009:adverse effects; D003847:Deoxyglucose / Q000494:pharmacology; D004299:Dopamine beta-Hydroxylase / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D008297:Male; D011132:Polyribosomes / Q000187:drug effects / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013315:Stress, Psychological / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics* / Q000378:metabolism*
D000963:Antimetabolites; D012333:RNA, Messenger; D003847:Deoxyglucose; D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase