Adropin has been shown to be involved in the regulation of food intake in mice. However, the mechanism of adropin in feeding regulation is still largely unknown. Using the tilapia, Oreochromis niloticus, we identified and characterized a novel form of adropin (designated adropin-b) encoding a 68-amino acid precursor. Although adropin-b shared low amino acid identities with its tilapia paralog (designated adropin-a), synteny analysis proved that tilapia adropin is orthologous to its human counterpart. The transcripts of adropin-b were ubiquitously expressed in various tissues with the highest levels in the olfactory bulb. A decrease in adropin-b mRNA levels was observed 1 h following a meal in the olfactory bulb, hypothalamus, and optic tectum, whereas fasting for 7 days induced an increase in adropin-b mRNA levels in the olfactory bulb, hypothalamus, and optic tectum of tilapia brain. However, no changes in adropin-a mRNA levels were observed in the postprandial and fasting state. Intraperitoneal injection of tilapia adropin-b was shown to increase food consumption, but adropin-a did not affect feeding. Co-treatment of the fish with adropin-b and neuropeptide Y (NPY) had no additive effects on appetite. The appetite stimulatory effects of adropin-b appeared to be mediated by upregulating the orexigenic Npy, Orexin, and Proapelin gene expression, paralleled by inhibition of the mRNA levels of anorexigenic proopiomelanocortin (Pomc) and cocaine-amphetamine-regulated transcript (Cart) in vivo and in vitro. These observations suggested that adropin-b participated in appetite control and gene regulation of central orexigenic and anorexigenic factors in a fish model.

Adropin 已被证明参与调节小鼠的食物摄入。然而，adropin 在摄食调节中的机制仍然很大程度上未知。我们使用罗非鱼Oreochromis niloticus鉴定并表征了一种新形式的 adropin（指定为 adropin-b），编码 68 个氨基酸的前体。尽管 adropin-b 与其罗非鱼旁系同源物（指定为 adropin-a）共享低氨基酸同一性，但同线性分析证明罗非鱼 adropin 与其人类对应物直系同源。adropin-b的转录物在各种组织中普遍表达，在嗅球中表达水平最高。adropin-b减少餐后 1 小时观察到嗅球、下丘脑和视顶盖中的mRNA 水平，而禁食 7 天会诱导罗非鱼大脑的嗅球、下丘脑和视顶盖中的adropin-b mRNA 水平增加。然而，在餐后和空腹状态下没有观察到adropin-a mRNA 水平的变化。腹腔注射罗非鱼 adropin-b 显示增加食物消耗，但 adropin-a 不影响进食。用 adropin-b 和神经肽 Y (NPY) 共同处理鱼对食欲没有附加影响。adropin-b 的食欲刺激作用似乎是通过上调促食欲Npy、Orexin和Proapelin介导的基因表达，同时在体内和体外抑制厌食症原阿片黑素皮质素 ( Pomc ) 和可卡因-苯丙胺调节的转录物 ( Cart )的 mRNA 水平。这些观察结果表明，adropin-b 参与了鱼类模型中中枢促食欲和促食欲因素的食欲控制和基因调控。