Entringer Petter F, Majerowicz David, Gondim Katia C
Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Departamento de Biotecnologia Farmacêutica, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Front Physiol. 2021 Apr 1;12:654565. doi: 10.3389/fphys.2021.654565. eCollection 2021.
Insects are unable to synthesize cholesterol and depend on the presence of sterols in the diet for cell membrane composition and hormone production. Thus, cholesterol absorption, transport, and metabolism are potential targets for vector and pest control strategies. Here, we investigate the dietary cholesterol absorption and tissue distribution in the kissing bug using radiolabeled cholesterol. Both the anterior and posterior midguts absorbed cholesterol from the ingested blood, although the anterior midgut absorbed more. We also observed esterified cholesterol labeling in the epithelium, indicating that midgut cells can metabolize and store cholesterol. Only a small amount of labeled cholesterol was found in the hemolymph, where it was mainly in the free form and associated with lipophorin (Lp). The fat body transiently accumulated cholesterol, showing a labeled cholesterol peak on the fifth day after the blood meal. The ovaries also incorporated cholesterol, but cumulatively. The insects did not absorb almost half of the ingested labeled cholesterol, and radioactivity was present in the feces. After injection of H-cholesterol-labeled Lp into females, a half-life of 5.5 ± 0.7 h in the hemolymph was determined. Both the fat body and ovaries incorporated Lp-associated cholesterol, which was inhibited at low temperature, indicating the participation of active cholesterol transport. These results help describe an unexplored part of lipid metabolism.
昆虫无法合成胆固醇，它们依赖食物中的甾醇来构成细胞膜和产生激素。因此，胆固醇的吸收、运输和代谢是控制病媒和害虫策略的潜在靶点。在此，我们使用放射性标记的胆固醇来研究猎蝽对食物中胆固醇的吸收及在组织中的分布情况。前中肠和后中肠都能从摄入的血液中吸收胆固醇，不过前中肠吸收得更多。我们还在上皮细胞中观察到了酯化胆固醇标记，这表明中肠细胞能够代谢和储存胆固醇。在血淋巴中仅发现少量标记胆固醇，且主要以游离形式存在，并与脂蛋白（Lp）相关。脂肪体短暂积累胆固醇，在吸血后第5天出现标记胆固醇峰值。卵巢也会累积性地摄取胆固醇。昆虫几乎没有吸收近一半摄入的标记胆固醇，粪便中存在放射性。向雌性猎蝽注射H - 胆固醇标记的Lp后，测得其在血淋巴中的半衰期为5.5±0.7小时。脂肪体和卵巢都摄取了与Lp相关的胆固醇，低温会抑制这种摄取，这表明存在活跃的胆固醇运输过程。这些结果有助于描述脂质代谢中一个未被探索的部分。
