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The effect of ionophore A23187 on the ability of dopamine and somatostatin to inhibit forskolin and TPA-stimulated prolactin and growth hormone release from sheep anterior pituitary cells


, : The effect of ionophore A23187 on the ability of dopamine and somatostatin to inhibit forskolin and TPA-stimulated prolactin and growth hormone release from sheep anterior pituitary cells. Journal Of Endocrinology 121(3 Suppl)

Ionophore A23187-stimulated growth hormone and prolactin release from sheep anterior pituitary cells is inhibited by somatostatin and dopamine, respectively. This effect is mediated by one or more pertussis toxin-sensitive G proteins (Boyd and Wallis, 1988a), indicating that both dopamine and somatostatin may have calcium-independent actions. TPA and forskolin-stimulated growth hormone and prolactin release are also inhibited by dopamine and somatostatin, via pertussis toxin-sensitive G protein(s) (Boyd and Wallis, 1988b). In order to investigate the role of Ca2+ in the inhibitory actions of dopamine and somatostatin, A23187 was used to elevate intracellular [Ca2+] in the presence of TPA and forskolin, and the actions of dopamine and somatostatin were investigated. Ovine pituitary cells were prepared and maintained in culture as described previously (Ray and Wallis, 1982). The ability of somatostatin (100 nM) to inhibit forskolin (10 uM) and TPA (100 nM)-stimulated growth hormone release was not significantly affected by 1 uM ionophore. At 10 uM the ionophore blocked the action of somatostatin to a small but significant extent. Dopamine (100 nM) inhibited stimulatory effects of forskolin (10 uM) and TPA (100 nM) on prolactin release and this was not significantly affected by 1 µ ionophore. 10 µ ionophore blocked the inhibitory action of dopamine on forskolinstimulated prolactin release by 50% and in some experiments partially blocked the inhibition of TPA-stimulated prolactin release due to dopamine. In conclusion, only at high ionophore concentration was a partial reversal of the inhibitory effects of somatostatin and dopamine seen. This confirms previous suggestions that dopamine and somatostatin may have Ca2±independent actions.

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McCann, B.W.; Acevedo, O., 2013: Pairwise Alternatives to Ewald Summation for Calculating Long-Range Electrostatics in Ionic Liquids. Room temperature ionic liquid calculations require extensive sampling due to the large degree of localized structuring in the liquid phase relative to conventional solutions. Consequently, a large amount of computer time is required for the conver...

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Coulanges, P.; Zeller, H.; Clerc, Y.; Rodhain, F.; Albignac, R., 1980: Bacteria, viruses, parasites, pathology and experimental pathology of Malagasy Lemurs. Interest for man. Archives de L'institut Pasteur de Madagascar 47(1): 201-219

Nomura, T.; Tani, S.; Yamamoto, M.; Nakagawa, T.; Toyoda, S.; Fujisawa, E.; Yasui, A.; Konishi, Y., 2016: Cytotoxicity and colloidal behavior of polystyrene latex nanoparticles toward filamentous fungi in isotonic solutions. The effects of surface physicochemical properties of functionalized polystyrene latex (PSL) nanoparticles (NPs) and model filamentous fungi Aspergillus oryzae and Aspergillus nidulans cultivated in different environment (aqueous and atmospheric en...

Ciesielski, B.G.; Armstrong, T.; Zald, D.H.; Olatunji, B.O., 2011: Emotion modulation of visual attention: categorical and temporal characteristics. Experimental research has shown that emotional stimuli can either enhance or impair attentional performance. However, the relative effects of specific emotional stimuli and the specific time course of these differential effects are unclear. In the...

McGavin, L., 1913: Resection of Cæcum, Ileocæcal Valve, Appendix, and 10 in. of Ileum for Obstruction following an Entero-anastomosis; subsequent Ventral Hernia cured by Filigree Inplantation. Proceedings of the Royal Society of Medicine 6(Clin Sect): 36-36

Shiyake, Shigehiko, 1994: On the hind tibial spurs in the genus Mordellistena. Bulletin of the Osaka Museum of Natural History 0(48): 9-22

Goss, K-Uwe., 2008: The pKa values of PFOA and other highly fluorinated carboxylic acids. The dissociated and nondissociated species of any organic acid differ largely in their physicochemical behavior. The ratio of both species in aqueous systems is determined by the respective pK(a) value. For perfluorooctanoic acid recent fate-model...

Kairyukshtis, L.; Shakunas, Z., 1990: Effect of forest machines on the soil. Details are given of soil compaction and rut formation by forestry machines (especially multi-operation harvesting equipment) on fresh and moist soils, with normal operation (i.e. the machines restricted to defined tracks) and with unregulated ope...

Money M.S., 1983: Dam and reservoir construction in glaciated valleys. Pages 318-348 1983