کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9416421 | 1614334 | 2005 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Progesterone regulation of catecholamine secretion from chromaffin cells
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علم عصب شناسی
علوم اعصاب (عمومی)
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چکیده انگلیسی
Stress stimulates the adrenal medulla to rapidly secrete catecholamines (CAs), and the adrenal cortex to release progesterone (PROG), which may locally regulate stress-induced CA release. We used bovine chromaffin cells to investigate the effects of PROG on CA secretion. PROG dose-dependently inhibited CA secretion induced by nicotinic acetylcholine receptor (nAChR) agonist 1,1-dimethyl-4-phenlypiperazinium iodide (DMPP) up to 77%. Pre-incubation with PROG up to 1 h increased this inhibition. 3α,5α-Tetrahydroprogesterone (3α,5α-THP) and dexamethasone were less potent inhibitors. Patch-clamp techniques revealed that PROG co-applied with DMPP inhibited peak DMPP-induced current up to 68% and with 3 min pre-incubation inhibited both peak and integrated current up to â¼95%. Monitoring of FURA-2 showed that PROG similarly inhibited parallel changes in intracellular-free Ca++ concentration. PROG also inhibited CA secretion elicited by elevated K+ (38%), and, in single cells, suppressed Ca++ current evoked by step depolarization, inhibiting amplitude by 15%, and reducing the time constant of current decay during depolarization by 57%. In contrast to the immediate inhibition of nicotinic current, inhibition of Ca++ current became statistically significant only after 1 min exposure to PROG. PROG did not inhibit secretion stimulated by high Ca++ perfusion of permeabilized cells. These data suggest that PROG inhibits CA secretion from chromaffin cells predominantly by rapidly inhibiting nAChRs, and by gradually enhancing the inactivation of voltage-dependent Ca++ channels (VDCCs), but not by affecting secretory processes downstream of Ca++ influx. This study supports a role for adrenocortical PROG in the regulation of CA secretion during stress.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Brain Research - Volume 1043, Issues 1â2, 10 May 2005, Pages 76-86
Journal: Brain Research - Volume 1043, Issues 1â2, 10 May 2005, Pages 76-86
نویسندگان
Siobhan M. Armstrong, Edward L. Stuenkel,