Mechanisms of action of melanin-concentrating hormone in the teleost fish erythrophoroma cell line (GEM-81).
Melanin-concentrating hormone (MCH) evokes an increase of GEM-81 cell proliferation. This action of 10(-6)M MCH was inhibited in the presence of the following blockers: U-73122 (phospholipase C), Ro-31-8220 (PKC) or KN-93 (Ca(2+)/calmodulin-dependent kinase). The more selective PKC inhibitors, HBDDE and Go-6983, which block, respectively, PKC alpha/gamma isoform and beta1 isoform, were used. HBDDE was ineffective whereas Go-6983 reversed the proliferative response promoted by MCH. Flow cytometry assays demonstrated that MCH induces a slow and long-lasting rise in intracellular calcium, which can be blocked by U-73122. Our results also show a cAMP increase evoked by MCH. Our data support the assumption that MCH exerts its effect on GEM-81 erythrophoroma cells through activation of phosholipase C, beta1 PKC, and Ca(2+)/calmodulin-dependent PKC, and eliciting a slow, long-lasting rise in calcium, which may trigger the proliferative signal.
Isoldi
Mauro César
MC
Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
de Pina Benabou
Mara Helena
MH
Schumacher
Robert Ivan
RI
Góis
Carolina Costa
CC
Scarparo
Ana Cristina
AC
Rebouças
Nancy Amaral
NA
Visconti
Maria Aparecida
MA
D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005393:Fish Diseases / Q000473:pathology; D006054:Goldfish; D007028:Hypothalamic Hormones / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D008543:Melanins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010907:Pituitary Hormones / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D012878:Skin Neoplasms / Q000473:pathology / Q000662:veterinary; D013449:Sulfonamides / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D000096926:Benzenesulfonamides
D001596:Benzylamines; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D004963:Estrenes; D007028:Hypothalamic Hormones; D007211:Indoles; D008543:Melanins; D010907:Pituitary Hormones; D011493:Protein Kinase C; D011760:Pyrrolidinones; D013449:Sulfonamides; D010738:Type C Phospholipases; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C072105:KN 93; D000096926:Benzenesulfonamides; C019463:melanin-concentrating hormone; C064758:Ro 31-8220