Stimulus-secretion coupling in porcine adrenal chromaffin cells: acute effects of glucocorticoids.
Recent studies from this laboratory have established that long-term exposure (48 hr) to glucocorticoids can modulate voltage-gated Ca(2+) channel activity and subsequent intracellular Ca(2+) transients in porcine adrenal medullary chromaffin (PAMC) cells maintained in primary culture. Consistent with many steroid hormone-mediated responses, this chronic effect of glucocorticoids probably involves increased gene expression and protein synthesis. However, there is now considerable evidence to suggest that steroids can also elicit acute, non-genomic effects. The aim of the present study was to determine whether acute exposure to glucocorticoids also affects nicotinic receptor-dependent catecholamine (CAT) secretion and Ca(2+) signaling in PAMC cells. Acute exposure to dexamethasone (DEX) dose-dependently attenuated the degree of nicotine (NIC)-induced CAT secretion, as well as the amplitude of NIC-induced intracellular Ca(2+) transients. Significant inhibition of CAT secretion occurred immediately upon addition of DEX, reached maximal levels within 5 min of exposure to DEX, and was rapidly reversible after steroid washout. The endogenous porcine glucocorticoid cortisol elicited similar effects. In contrast, DEX had no significant effect on KCl-induced CAT secretion or intracellular Ca(2+) transients. These data demonstrate that acute exposure to glucocorticoids can modulate stimulus-secretion coupling in PAMC cells and suggest that the primary site of action is the nicotinic receptor.
Wagner
P G
PG
Department of Physiology, University of Kentucky, Lexington 40536-0298, USA.
Jorgensen
M S
MS
Arden
W A
WA
Jackson
B A
BA
D000313:Adrenal Medulla / Q000166:cytology / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002395:Catecholamines / Q000378:metabolism*; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology*; D009538:Nicotine / Q000494:pharmacology*; D013552:Swine
D015220:Calcium Channels; D002395:Catecholamines; D009538:Nicotine; D003907:Dexamethasone; D002118:Calcium; D006854:Hydrocortisone