title: Cross-regulation of cortisol secretion by adrenocorticotropin and platelet-activating factor in perfused guinea pig adrenals.
abstract: We examined the cross-regulation of signaling between ACTH-and platelet-activating factor (PAF)-mediated steroidogenesis in the perfused guinea pig adrenal gland. Our method of in situ perfusion using an artificial medium can evaluate whether cortisol secretion in response to ACTH and PAF is interactive. Treating adrenal glands with 100 pg/ml ACTH diminished the subsequent cortisol response to 10 nM PAF. By contrast, PAF resulted in subsequent potentiation of ACTH-induced cortisol secretion. A mixture of 50 microM L-alpha-1-oleoyl-2-acetyl-sn-glycerol (OAG), an activator of protein kinase C (PKC), and 3.3 microM calcium ionophore (A23187), or 10 microM forskolin (FRK) diminished the cortisol response to PAF, whereas that to ACTH was unaffected. Each of PAF, ACTH, or FRK eliminated the cortisol response to OAG plus A23187, whereas that to FRK was unaffected. These data show that the protein kinase A (PKA)-dependent processes activated by ACTH or FRK can interfere with PAF-induced signal transduction at receptor and post-receptor levels. In contrast, PKC-dependent processes activated by PAF promoted ACTH-signaling at receptor and post-receptor level. Cross-regulation between processes activated by PAF receptor-PKC and by ACTH receptor-PKA might function in the multifactorial regulation of adrenocortical steroidogenesis.
authors.affiliation: Department of Physiology, Nagasaki University School of Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto-machi, Nagasaki 852-8523, Japan. tshimada@net.nagasaki-u.ac.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Shimada
authors.forename: Taeko
authors.initials: T
authors.lastname: Hirose
authors.forename: Itsuro
authors.initials: I
authors.lastname: Matsumoto
authors.forename: Tadaomi
authors.initials: T
authors.lastname: Aikawa
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000378:metabolism*; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D009924:Organ Culture Techniques; D010972:Platelet Activating Factor / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: C520323:1-oleoyl-2-acetoyl-sn-glycerol; D004075:Diglycerides; D004791:Enzyme Inhibitors; D007476:Ionophores; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D005576:Colforsin; D000001:Calcimycin; D000324:Adrenocorticotropic Hormone; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D006854:Hydrocortisone