Abstract
Orexins, orexigenic neuropeptides, have recently been discovered in lateral hypothalamus and play an important role in the regulation of pituitary hormone secretion. Two subtypes of orexin receptors (orexin-1 and orexin-2) have been demonstrated in pituitaries. In this experiment, the effects of orexins on voltage-gated Ca2+ currents and the GH release in primary cultured ovine somatotropes were examined. Voltage-gated Ca2+ currents were isolated in ovine somatotropes as L, T, and N currents using whole-cell patch-clamp techniques and specific Ca2+ channel blocker and toxin. Application of orexin-A or orexin-B (100 nM) significantly, dose-depen-dently, and reversibly increased only nifedipine-sensitive L-type Ca2+ current. Inhibitors of PKC (calphostin C, PKC inhibitory peptide) but not inhibitors of PKA (H89, PKA inhibitory peptide) cancelled the increase in the L current by orexins. Co-administration of orexin-A and GHRH (10 nM) showed an additive effect on the L current. Specific intracellular Ca2+-store-depleting reagent, thapsigargin (1 µM), did not affect the orexin-induced increase in the L current. Orexin-B alone slightly increased GH release and co-administration of orexin-A and GHRH synergistically stimulated GH secretion in vitro. It is therefore suggested that orexins may play an important role in regulating GHRH-stimulated GH secretion through an increase in the L-type Ca2+ current and the PKC-mediated signaling pathways in ovine somatotropes.
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de Lecea, L., Kilduff, T. S., Peyron, C., et al. (1998). Proc. Natl. Acad. Sci. USA 95, 322–327.
Sakurai, T., Amemiya, A., Ishii, M., et al. (1998). Cell 92, 573–585.
Hagan, J. J., Leslie, R. A., Patel, S., et al. (1999). Proc. Natl. Acad. Sci. USA 96, 10911–10916.
Mondal, M. S., Nakazato, M., and Matsukura, S. (2000). Biochem. Cell Biol. 78, 299–305.
de Lecea, L. and Sutcliffe, J. G. (1999). Cell Mol. Life Sci. 56, 473–480.
Mazzocchi, G., Malendowicz, L. K., Aragona, F., Rebuffat, P., Gottardo, L., and Nussdorfer, G. G. (2001). J. Clin. Endocrinol. Metab. 86, 4818–4821.
Date, Y., Ueta, Y., Yamashita, H., et al. (1999). Proc. Natl. Acad. Sci. USA 96, 748–753.
Date, Y., Mondal, M. S., Matsukura, S., et al. (2000). Brain Res. Mol. Brain Res. 76, 1–6.
Xu, R., Wang, Q., Yan, M., et al. (2002). Endocrinology 143, 4609–4619.
Blanco, M., Lopez, M., GarcIa-Caballero, T., et al. (2001). J. Clin. Endocrinol. Metab. 86, 1616–1619.
Johren, O., Neidert, S. J., Kummer, M., Dendorfer, A., and Dominiak, P. (2001). Endocrinology 142, 3324–3331.
Pu, S., Jain, M. R., Kalra, P. S., and Kalra, S. P. (1998). Regul. Pept. 78, 133–136.
Russell, S. H., Kim, M. S., Small, C. J., et al. (2000). J. Neuroendocrinol. 12, 1213–1218.
Jaszberenyi, M., Bujdoso, E., Pataki, I., and Telegdy, G. (2000). J. Neuroendocrinol. 12, 1174–1178.
Irahara, M., Tamura, T., Matuzaki, T., et al. (2001). Biochem. Biophys. Res. Commun. 281, 232–236.
Mazzocchi, G., Malendowicz, L. K., Gottardo, L., Aragona, F., and Nussdorfer, G. G. (2001). J. Clin. Endocrinol. Metab. 86, 778–782.
Mitsuma, T., Hirooka, Y., Mori, Y., et al. (1999). Horm. Metab. Res. 31, 606–609.
Nowak, K. W., Mackowiak, P., Switonska, M. M., Fabis, M., and Malendowicz, L. K. (2000). Life Sci. 66, 449–454.
Samson, W. K. and Taylor, M. M. (2001). Am. J. Physiol. Regul. Integr. Comp. Physiol. 281, R1140-R1145.
van den Pol, A. N., Gao, X. B., Obrietan, K., Kilduff, T. S., and Belousov, A. B. (1998). J. Neurosci. 18, 7962–7971.
Grudt, T. J., van den Pol, A. N. and Perl, E. R. (2002). J. Physiol. 538, 517–525.
Chen, C., Vincent, J. D., and Clarke, I. J. (1994). Trend Endocrinol. Metab. 5, 227–233.
Chen, C. and Clarke, I. J. (1995). Am. J. Physiol. 268, E204-E212.
Tsien, R. W., Fox, A. P., Hess, P., et al. (1987). Soc. Gen. Physiol. Ser. 41, 167–187.
Glassmeier, G., Hauber, M., Wulfsen, I., Weinsberg, F., Bauer, C. K., and Schwarz, J. R. (2001). Pflugers Arch. 442, 577–587.
Chen, C. and Clarke, I. J. (1995). J. Neuroendocrinol. 7, 179–186.
Chen, C., Zhang, J., Dayanithi, G., Vincent, J. D., and Israel, J. M. (1989). Neurochem. Int. 15, 265–275.
Kato, M. and Sakuma, Y. (1997). Endocrinology 138, 5096–5100.
Takei, T., Takano, K., Yasufuku-Takano, J., Fujita, T., and Yamashita, N. (1996). Am. J. Physiol. 271, E801-E807.
Xu, R., Clarke, I. J., Chen, S., and Chen, C. (2000). J. Neuroendocrinol. 12, 147–157.
Wetzel, C. H., Spehr, M., and Hatt, H. (2001). Eur. J. Neurosci. 14, 1056–1064.
Wu, D., Chen, C., Zhang, J., Bowers, C. Y., and Clarke, I. J. (1996). J. Endocrinol. 148, 197–205.
Stojilkovic, S. S., Izumi, S., and Catt, K. J. (1988). J. Biol. Chem. 263, 13054–13061.
Ramirez, J. L., Torronteras, R., Malagon, M. M., et al. (1998). Cell Calcium 23, 207–217.
Kwiecien, R. and Hammond, C. (1998). Neuroendocrinology 68, 135–151.
Rodgers, R. J., Halford, J. C., Nunes de Souza, R. L., et al. (2000). Regul. Pept. 96, 71–84.
Stea, A., Soong, T. W., and Snutch, T. P. (1995). Neuron 15, 929–940.
Zong, S., Yassin, M., and Tanabe, T. (1995). Biochem. Biophys. Res. Commun. 215, 302–308.
Washburn, D. L. and Ferguson, A. V. (2001). J. Physiol. 536, 667–675.
Cataldi, M., Taglialatela, M., Guerriero, S., et al. (1996). J. Biol. Chem. 271, 9441–9446.
Tse, A. and Hille, B. (1993). Endocrinology 132, 1475–1481.
Heyward, P. M., Chen, C., and Clarke, I. J. (1995). Neuroendocrinology 61, 609–621.
Charles, A. C., Piros, E. T., Evans, C. J., and Hales, T. G. (1999). J. Biol. Chem. 274, 7508–7515.
Shiraishi, T., Oomura, Y., Sasaki, K., and Wayner, M. J. (2000). Physiol. Behav. 71, 251–261.
Takei, T., Yasufuku-Takano, J., Takano, K., Fujita, T., and Yamashita, N. (1998). Am. J. Physiol. 275, E649-E654.
Adams, E. F., Lei, T., Buchfelder, M., Bowers, C. Y., and Fahlbusch, R. (1996). Mol. Endocrinol. 10, 432–438.
Uramura, K., Funahashi, H., Muroya, S., Shioda, S., Takigawa, M., and Yada, T. (2001). Neuroreport 12, 1885–1889.
van den Pol, A. N. (1999). J. Neurosci. 19, 3171–3182.
Lussier, B. T., French, M. B., Moor, B. C., and Kraicer, J. (1991). Endocrinology 128, 592–603.
Chen, C., Wu, D., and Clarke, I. J. (1996). J. Endocrinol. 148, 381–386.
Xu, R., Roh, S. G., Loneragan, K., Pullar, M., and Chen, C. (1999). J. Physiol. 520(Pt 3), 697–707.
Lei, T., Adams, E. F., Buchfelder, M., and Fahlbusch, R. (1996). Neurosurgery 39, 569–575.
Cheng, K., Chan, W. W., Butler, B., Barreto, A. Jr., and Smith, R. G. (1991). Endocrinology 129, 3337–3342.
Lund, P. E., Shariatmadari, R., Uustare, A., et al. (2000). J. Biol. Chem. 275, 30806–30812.
Kukkonen, J. P. and Akerman, K. E. (2001). Neuroreport 12, 2017–2020.
Felder, C. C., Poulter, M. O., and Wess, J. (1992). Proc. Natl. Acad. Sci. USA 89, 509–513.
Zerbes, M., Bunn, S. J., and Powis, D. A. (1998). Cell Calcium 23, 379–386.
Hwang, L. L., Chen, C. T., and Dun, N. J. (2001). J. Physiol. 537, 511–520.
Rauch, M., Riediger, T., Schmid, H. A., and Simon, E. (2000). Pflugers Arch. 440, 699–703.
Ida, T., Nakahara, K., Kuroiwa, T., et al. (2000). Neurosci. Lett. 293, 119–122.
Komaki, G., Matsumoto, Y., Nishikata, H., et al. (2001). Eur. J. Endocrinol. 144, 645–651.
Chen, C., Heyward, P., Zhang, J., Wu, D., and Clarke, I. J. (1994). Neuroendocrinology 59, 1–9.
Xu, R., Zhao, Y., and Chen, C. (2003). Neuroendocrinology 77, 141–152.
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Chen, C., Xu, R. The in vitro regulation of growth hormone secretion by orexins. Endocr 22, 57–66 (2003). https://doi.org/10.1385/ENDO:22:1:57
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DOI: https://doi.org/10.1385/ENDO:22:1:57