The effect of catecholamines and adenosine on the induction of morphological alterations and depigmentation of newt iris epithelial cells in vitro.
Catecholamines and adenosine have a stimulating effect on the process of dedifferentiation of cultured iris epithelial cells (IECs) from the adult newt Notophthalmus viridescens. Micromolar concentrations of adrenergic ligands such as isoproterenol, norepinephrine, and epinephrine induced marked morphological alterations culminating in the stellate configuration and depigmentation of IECs. Dopamine at 100 microM or higher induced the morphological response, while serotonin was ineffective. The morphological change was transient, requiring 80-90 min for maximum induction, and only a fraction of the cells was responsive. The response was blocked by beta-adrenergic antagonists, such as propranolol and alprenolol, but not by alpha-adrenergic blockers. Adenosine at 10 microM, or higher, also induced morphological alterations of IECs. The effect of adenosine was partially blocked by various adenosine receptor antagonists. The effect of isoproterenol and norepinephrine on the induction of morphological alterations was potentiated by adenosine. The release of melanosomes from IECs was increased in the presence of catecholamines and adenosine. Catecholamines and adenosine at 10 microM increased the intracellular levels of cAMP of dedifferentiating dorsal irides. The increase in cAMP levels induced by isoproterenol was inhibited by propranolol and the adenosine receptor antagonist 5'-deoxy-5'-methyl thioadenosine (MTA) partially blocked the effect of adenosine. Our results suggest that adrenergic hormones may be coupled to a beta-adrenergic adenylate cyclase system. The presence of an adenosine receptor is also suggested by the results. Our data strongly support previous work in which cAMP and substances related to it induced morphological alterations and depigmentation of IECs. It is proposed that catecholamines and adenosine may participate in the regulation of dedifferentiation during the transdifferentiation of IECs into lens cells.
Torres
L D
LD
Natural Science Department, University of Puerto Rico, Carolina Regional College 00630.
Alonso
H M
HM
Ortiz
J R
JR
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D002395:Catecholamines / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D007498:Iris / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010858:Pigmentation / Q000187:drug effects*; D012455:Salamandridae / Q000378:metabolism*
D002395:Catecholamines; D000242:Cyclic AMP; D000241:Adenosine