Meredith M, Rabaglia M E, Corbett J A, Metz S A
Department of Medicine, University of Wisconsin, William S. Middleton Veteran's Administration Hospital, Madison, USA.
Diabetes. 1996 Dec;45(12):1783-91. doi: 10.2337/diab.45.12.1783.
Interleukin-1beta (IL-1beta) has been shown to inhibit glucose-induced insulin secretion from rat islets and purified beta-cells, primarily through the generation of nitric oxide (NO). However, the mechanisms by which NO exerts its effects remain unclear. To examine the role of purine nucleotides, we cultured intact rat islets or INS-1 (glucose-responsive transformed rat) beta-cells for 18 h in the presence or absence of IL-1beta. In islets, the exposure to IL-1beta (100 pmol/l) inhibited subsequent glucose-induced insulin secretion by 91% with no significant effect on insulin content or basal insulin release. IL-1beta also diminished insulin secretion induced by pure mitochondrial fuels, 40 mmol/l K+, or a phorbol ester. Concomitantly, IL-1beta significantly decreased islet ATP (-45%), GTP (-33%), ATP/ADP (-54%), and GTP/GDP (-46%). These effects were totally reversed by provision of N(omega)-nitro-L-arginine methyl ester (NAME) in arginine-free media that inhibited NO production. In contrast, in INS-1 cells, IL-1beta (10 or 100 pmol/l) reduced both basal and glucose-induced insulin secretion by 50%, but insulin content was also reduced by 35%. Therefore, the INS-1 cells were still able to respond to glucose stimulation with a 1.8-2.0-fold increase in insulin release in either the presence or absence of IL-1beta. Concomitantly, in INS-1 cells, IL-1beta had no effect on ATP/ADP or GTP/GDP ratios, although it modestly decreased ATP (-25%) and GTP (-22%). As in islets, all effects of IL-1beta in INS-1 cells were prevented by NAME. Thus, in rat islets, IL-1beta (via the generation of NO) abolishes insulin exocytosis in association with large decreases in the ATP/ADP (and GTP/GDP) ratio, implying the impairment of mitochondrial function. Furthermore, IL-1beta inhibits cytosolic synthesis of new purine nucleotides (via the salvage pathway), as assessed by a decrease in their specific activity after labeling with [3H]hypoxanthine. In contrast, in INS-1 cells, IL-1beta appears to impair cytosolic synthesis of purine nucleotides and insulin biosynthesis selectively (both possibly reflecting decreased glycolysis) with little direct effect on insulin exocytosis itself.
白细胞介素-1β（IL-1β）已被证明可抑制大鼠胰岛和纯化的β细胞中葡萄糖诱导的胰岛素分泌，主要是通过一氧化氮（NO）的生成。然而，NO发挥其作用的机制仍不清楚。为了研究嘌呤核苷酸的作用，我们在有或无IL-1β的情况下将完整的大鼠胰岛或INS-1（葡萄糖反应性转化大鼠）β细胞培养18小时。在胰岛中，暴露于IL-1β（100 pmol/l）可使随后葡萄糖诱导的胰岛素分泌减少91%，而对胰岛素含量或基础胰岛素释放无显著影响。IL-1β还可减少由纯线粒体燃料、40 mmol/l K+或佛波酯诱导的胰岛素分泌。同时，IL-1β可显著降低胰岛中的ATP（-45%）、GTP（-33%）、ATP/ADP（-54%）和GTP/GDP（-46%）。在无精氨酸培养基中提供N（ω）-硝基-L-精氨酸甲酯（NAME）抑制NO生成后，这些作用完全逆转。相比之下，在INS-1细胞中，IL-1β（10或100 pmol/l）可使基础和葡萄糖诱导的胰岛素分泌均减少50%，但胰岛素含量也减少了35%。因此，无论有无IL-1β，INS-1细胞仍能对葡萄糖刺激作出反应，胰岛素释放增加1.8至2.0倍。同时，在INS-1细胞中，IL-1β对ATP/ADP或GTP/GDP比值无影响，尽管它适度降低了ATP（-25%）和GTP（-22%）。与在胰岛中的情况一样，NAME可阻止IL-1β在INS-1细胞中的所有作用。因此，在大鼠胰岛中，IL-1β（通过生成NO）消除胰岛素胞吐作用，同时ATP/ADP（和GTP/GDP）比值大幅下降，这意味着线粒体功能受损。此外，通过用[3H]次黄嘌呤标记后其比活性的降低评估，IL-1β抑制新嘌呤核苷酸的胞质合成（通过补救途径）。相比之下，在INS-1细胞中，IL-1β似乎选择性地损害嘌呤核苷酸的胞质合成和胰岛素生物合成（两者可能都反映糖酵解减少），而对胰岛素胞吐作用本身几乎没有直接影响。
