本研究旨在探讨雷帕霉素复合物1(TORC1)信号通路在种鸽作物乳合成中的调控作用。3组哺乳期种鸽(n=30对/组)分别注射雷帕霉素(RAPA,雷帕霉素复合物靶标的特异性抑制剂),剂量为0(媒介物,control),0.6,或1.2mg/kg体重(BW)/天,通过翼静脉持续7天。在整个实验期间,分别记录了种鸽的平均每日采食量(ADFI)和BW以及幼鸽的BW。繁殖的鸽子被处死以收集它们的作物组织,农作物牛奶,和血清在实验的第八天。结果表明,0.6和1.2mg/kgBWRAPA注射液均不影响种鸽的BW损失和ADFI(P>0.05)。在1.2mg/kgBW雷帕霉素注射组中,作物厚度和作物相对重量显着降低(P<0.05)。同时,RAPA(特别是在1.2mg/kgBW时)降低了粗蛋白,αs1-酪蛋白,αs2-酪蛋白,β-酪蛋白,和氨基酸含量(Asp,Thr,Ser,Glu,Gly,阿拉,Cys,Val,Met,Ile,Leu,Tyr,Lys,他的,Arg,和Pro)的农作物奶(P<0.05)和白蛋白的浓度,总蛋白质,种鸽血清中的尿酸(P<0.05)。此外,通过0.6或1.2mg/kgBW/天的RAPA注射,种鸽作物组织中TORC1通路相关蛋白(TORC1,S6K1,S6,4EBP1和eIF4E)的表达下调(P<0.05)。因此,幼仔的平均日增重(ADG)下降,死亡率明显增加(P<0.05)。一起,结果表明,RAPA降低了种鸽作物乳汁中的蛋白质和氨基酸水平,阻碍了雏鸽的生长,表明TORC1在培育鸽子的作物乳合成中的关键作用。
This study was conducted to explore the regulatory role of the target of rapamycin complex 1 (TORC1) signaling pathway in crop milk synthesis in breeding pigeons (Columba livia). Three groups of breeding pigeons in the lactation period (n = 30 pairs/group) were respectively injected with rapamycin (RAPA, a specific inhibitor of the target of rapamycin complex) at doses of 0 (vehicle, control), 0.6, or 1.2 mg/kg body weight (BW)/day via the wing vein for 7 days. The average daily feed intake (ADFI) and BW of the breeding pigeons and the BW of young squabs were respectively recorded throughout the experimental period. The breeding pigeons were sacrificed to collect their crop tissues, crop milk, and serum on the eighth day of the experiment. The results showed that neither 0.6 nor 1.2 mg/kg BW RAPA injection affected BW loss or ADFI in breeding pigeons (P > 0.05), while crop thickness and crop relative weight were significantly decreased (P < 0.05) in the 1.2 mg/kg BW rapamycin-injected group. Simultaneously, RAPA (especially at 1.2 mg/kg BW) decreased the crude protein, αs1-casein, αs2-casein, β-casein, and amino acid contents (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Tyr, Lys, His, Arg, and Pro) of crop milk (P < 0.05) and the concentrations of albumin, total protein, and uric acid in the serum of breeding pigeons (P < 0.05). Additionally, the expression of TORC1 pathway-related proteins (TORC1, S6K1, S6, 4EBP1, and eIF4E) was downregulated in the crop tissues of breeding pigeons by 0.6 or 1.2 mg/kg BW/day RAPA injection (P < 0.05). Accordingly, the average daily gain (ADG) of young squabs declined, and the mortality rate increased significantly (P < 0.05). Together, the results showed that RAPA reduced protein and amino acid levels in the crop milk of breeding pigeons and retarded young squab growth, suggesting a crucial role of TORC1 in crop milk synthesis in breeding pigeons.