α‐Melanocyte‐stimulating hormone secretion from permeabilized intermediate lobe cells of rat pituitary gland The role of guanine nucleotides

FEBS Letters

Yamamoto, Toshifumi²  Kebabian, John W.²  Spatz, Maria¹  Furuki, Yoshihiro² 

[1] Laboratory of Neuropathology and Neuroanatomical Sciences, NINCDS, National Institute of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA;Experimental Therapeutics Branch, NINCDS National Institute of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA

关键词: GTP;    Permeabilization;    cyclic AMP;    Exocytosis;    (Pituitary intermediate cell);   

DOI  :  10.1016/0014-5793(87)80245-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The non-hydrolyzable GTP analogue, guanosine 5′-O-(3-thiotriphosphate) (GTPγS) and cyclic AMP potentiated the Ca²⁺-evoked secretion of α-melanocyte-stimulating hormone (α-MSH) from permeabilized neurointermediate lobe (IL) cells of rat pituitary gland. The enhancement by Mg-GTPγS (100 μM) and cyclic AMP (1 μM) depended on the intracellular CA²⁺ concentration (EC₅₀ = 4.8 ± 1.8 and 4.6 ± 1.7 μM; mean ± SE, with and without Mg-GTPγS and cyclic AMP, respectively). A similar effect was observed with guanine nucleotide triphosphate (GTP and GppNHp). Mg was absolutely required for this event. Neither Mg-GTPγS nor cyclic AMP alone was effective in potentiating α-MSH secretion. GDPβS blocked the Mg-GTPγS (100 μM) and cyclic AMP augmented secretion of α-MSH. Neither neomycin (which affects the process of inositol 1,4,5-triphosphate-mediated Ca²⁺ mobilization) or colchicine (which influences microtubule assembly) had an effect on the cyclic AMP and Mg-GTPγS potentiation of α-MSH secretion. These data suggest that the GTP-binding protein may be involved in the regulation of α-MSH secretion after Ca²⁺ entry into the cells, since the intracellular environment is controlled in the permeabilized cells.

【 授权许可】

Unknown