Escott Gustavo Monteiro, de Castro Alexandre Luz, Jacobus Ana Paula, Loss E S
Laboratório de Endocrinologia Experimental e Eletrofisiologia, Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Brazil.
Centro Universitário Metodista do IPA, Brazil.
Biochim Biophys Acta. 2014 May;1838(5):1332-7. doi: 10.1016/j.bbamem.2014.02.002. Epub 2014 Feb 11.
Insulin and insulin-like growth factor 1 (IGF-I) are capable of activating similar intracellular pathways. Insulin acts mainly through its own receptor, but can also activate the IGF-I receptor (IGF-IR). The aim of this study was to investigate the involvement of the IGF-IR in the effects of insulin and IGF-I on the membrane potential of immature Sertoli cells in whole seminiferous tubules, as well as on calcium, amino acid, and glucose uptake in testicular tissue of immature rats. The membrane potential of the Sertoli cells was recorded using a standard single microelectrode technique. In calcium uptake experiments, the testes were pre-incubated with (45)Ca(2+), with or without JB1 (1 μg/mL), and then incubated with insulin (100 nM) or IGF-I (15 nM). In amino acid and glucose uptake experiments, the gonads were pre-incubated with or without JB1 (1 μg/mL) and then incubated with radiolabeled amino acid or glucose analogues in the presence of insulin (100 nM) or IGF-I (15 nM). The blockade of IGF-IR with JB1 prevented the depolarising effects of both insulin and IGF-I on membrane potential, as well as the effect of insulin on calcium uptake. JB1 also inhibited the effects of insulin and IGF-I on glucose uptake. The effect of IGF-I on amino acid transport was inhibited in the presence of JB1, whereas the effect of insulin was not. We concluded that while IGF-I seems to act mainly through its cognate receptor to induce membrane depolarisation and calcium, amino acid and glucose uptake, insulin appears to be able to elicit its effects through IGF-IR, in seminiferous tubules from immature rats.
胰岛素和胰岛素样生长因子1（IGF-I）能够激活相似的细胞内信号通路。胰岛素主要通过自身受体发挥作用，但也能激活IGF-I受体（IGF-IR）。本研究的目的是探讨IGF-IR在胰岛素和IGF-I对未成熟支持细胞在整个生精小管中的膜电位以及对未成熟大鼠睾丸组织中钙、氨基酸和葡萄糖摄取的影响中的作用。使用标准的单微电极技术记录支持细胞的膜电位。在钙摄取实验中，睾丸先与（45）Ca（2+）预孵育，添加或不添加JB1（1μg/mL），然后与胰岛素（100 nM）或IGF-I（15 nM）孵育。在氨基酸和葡萄糖摄取实验中，性腺先添加或不添加JB1（1μg/mL）预孵育，然后在胰岛素（100 nM）或IGF-I（15 nM）存在的情况下与放射性标记的氨基酸或葡萄糖类似物孵育。用JB1阻断IGF-IR可防止胰岛素和IGF-I对膜电位的去极化作用以及胰岛素对钙摄取的作用。JB1还抑制胰岛素和IGF-I对葡萄糖摄取的作用。在存在JB1的情况下，IGF-I对氨基酸转运的作用受到抑制，而胰岛素的作用不受影响。我们得出结论，在未成熟大鼠的生精小管中，虽然IGF-I似乎主要通过其同源受体发挥作用以诱导膜去极化以及钙、氨基酸和葡萄糖摄取，但胰岛素似乎能够通过IGF-IR发挥其作用。
