Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, 36310 Vigo, Spain.
Domest Anim Endocrinol. 2011 Oct;41(3):126-36. doi: 10.1016/j.domaniend.2011.05.006. Epub 2011 Jun 29.
Although the role of ghrelin (GHRL) on fish appetite regulation had been widely studied in past years, its involvement in the regulation of glucose metabolism had been little explored. In the present study we hypothesize that GHRL may have a role in the regulation of glucose homeostasis in fish. Therefore, we carried out different experimental approaches in rainbow trout to assess brain glucosensing potential and glucose metabolism in response to GHRL treatment. We found that after either systemic or central GHRL administration to trout deprived of food, glycemia remained unaffected, whereas (in clear contrast with the mammalian model) a consistent activation of the main glucosensing markers (glucose transporter 2, glucokinase, and ATP-sensitive inward rectified K+ channel) was noticed in both hypothalamus and hindbrain. Some of these results were further confirmed by in vitro incubations of hypothalamus and hindbrain in the presence of GHRL. Despite the lack of changes in glycemia, we suggest that the changes elicited by GHRL on the glucosensing system are direct and could be related to a helper action of this hormone when glucose arrived in the postprandial phase. Moreover, we also studied the effect of GHRL treatment on the expression of several food intake-related neuropeptides, such as neuropeptide Y, cocaine- and amphetamine-regulated transcript, pro-opiomelanocortin, and corticotropin-releasing factor. We observed an important variability in the effects of GHRL attributable either to the route of GHRL administration or to the brain regions assessed, which could help explain the contradictory results described in fish literature about GHRL role in food intake control.
尽管近年来人们广泛研究了 ghrelin（GHRL）在鱼类摄食调节中的作用，但它在葡萄糖代谢调节中的作用却鲜有研究。在本研究中，我们假设 GHRL 可能在鱼类葡萄糖稳态调节中发挥作用。因此，我们采用不同的实验方法在虹鳟鱼中进行研究，以评估 GHRL 处理对大脑葡萄糖感应能力和葡萄糖代谢的影响。我们发现，在给禁食的鳜鱼进行全身或中枢注射 GHRL 后，血糖水平没有变化，而（与哺乳动物模型明显不同）在下丘脑和后脑中观察到主要葡萄糖感应标志物（葡萄糖转运蛋白 2、葡激酶和 ATP 敏感性内向整流钾+通道）持续激活。这些结果中的一些通过在存在 GHRL 的情况下对下丘脑和后脑进行体外孵育得到了进一步证实。尽管血糖水平没有变化，但我们认为 GHRL 对葡萄糖感应系统的变化是直接的，并且可能与这种激素在餐后葡萄糖进入时的辅助作用有关。此外，我们还研究了 GHRL 处理对几种与摄食相关的神经肽表达的影响，如神经肽 Y、可卡因和安非他命调节转录物、促黑激素原和促肾上腺皮质释放因子。我们观察到 GHRL 的作用存在重要的可变性，这种可变性归因于 GHRL 的给药途径或评估的脑区，这可以帮助解释鱼类文献中关于 GHRL 在摄食控制中的作用的矛盾结果。
