ISSN:
1573-6830
Keywords:
phenylethanolamineN-methyltransferase (PNMT)
;
adrenal medulla
;
glucocorticoids
;
transcriptional regulation
;
tyrosine hydroxylase (TH)
;
adrenocorticotropin (ACTH)
;
in situ hybridization
;
nuclear run-on transcription assays
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 1. PhenylethanolamineN-methyltransferase (PNMT) is regulated by glucocorticoid hormones. This study investigates the ability of glucocorticoids to modulate transcription of the rat PNMT genein vivo andin vitro. 2. In the adrenal glands of hypophysectomized (HPX'd) rats, the synthetic glucocorticoid dexamethasone (DEX) stimulates production of PNMT mRNA. Quantitative hybridization reveals that the levels of PNMT mRNA increase approximately threefold in total and poly(A)+ RNA after 4 days of DEX treatment of HPX'd rats, a level which is maximal for this treatment. 3. ACTH, the hormonal stimulus of glucocorticoid biosynthesis in the adrenal cortex, enhances PNMT mRNA production to levels comparable to that achieved with DEX in this system. The steroid responsiveness of PNMT message production is specific for glucocorticoids. DEX also increases PNMT mRNA in the brain stem, although the magnitude and speed of response are lower than observed in the adrenal gland. 4. Additional confirmation of the inductive ability of glucocorticoids is demonstrated by the increase in PNMT immunoprecipitated following translationin vitro of adrenal RNAs from DEX-treated rats. Furthermore, the PNMT mRNA signal obtained byin situ hybridization histochemistry in adrenal sections and in primary cultures of dispersed rat adrenal medullae reveals that DEX effects on PNMT mRNA can be elicited bothin vivo andin vitro. 5. Specifically, glucocorticoids exert their effects on expression of PNMT mRNA by elevating the rate of PNMT gene transcription: a 2.3-fold increase in PNMT transcription persists for 18 hr following DEX treatment of HPX'd rats. In summary, this study establishes that glucocorticoids directly and rapidly stimulate transcription of the rat PNMT gene.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00712926
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