期刊
ENDOCRINOLOGY
卷 154, 期 7, 页码 2393-2398出版社
ENDOCRINE SOC
DOI: 10.1210/en.2013-1136
关键词
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资金
- Fundacion Alfonso Martin Escudero [CD11/00276]
- Ministerio de Educacion y Ciencia e Innovacion [RYC-2007-00186, BFU2008-01136/BFI, BFU2010-19300]
- Junta de Andalucia [BIO-0139/CTS-5051]
- Department of Veterans Affairs, Office of Research and Development Merit Award [BX001114]
- National Institutes of Health [R01DK088133]
L-arginine (L-Arg) rapidly stimulates GH and insulin release in vivo. It has been hypothesized that L-Arg stimulates GH release by lowering hypothalamic somatostatin (SST) tone. L-Arg may also act directly at the pituitary to stimulate GH release. Moreover, L-Arg has a direct stimulatory effect on beta-cells, which is thought to be blunted by the release of SST from pancreatic delta-cells. To confirm the role of endogenous SST on L-Arg-induced GH and insulin release, wild-type (WT) and SST-knockout (SST-KO) mice were injected with L-Arg (ip; 0.8 g/kg), and pre-/post-injection GH, insulin, and glucose levels were measured. In WT mice, L-Arg evoked a 6-fold increase in circulating GH. However, there was only a modest increase in GH levels in WT pituitary cell cultures treated with L-Arg. In contrast, L-Arg failed to increase GH in SST-KO beyond their already elevated levels. These results further support the hypothesis that the primary mechanism by which L-Arg acutely increases GH in vivo is by lowering hypothalamic SST input to the pituitary and not via direct pituitary effects. Additionally, L-Arg induced a clear first-phase insulin secretion in WT mice, but not in SST-KO. However, SST-KO, but not WT mice, displayed a robust and sustained second-phase insulin release. These results further support a role for endogenous SST in regulating L-Arg-mediated insulin release. (Endocrinology 154: 2393-2398, 2013)
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