体外观察一氧化氮对约氏疟原虫雄配子形成的影响

目的 体外观察一氧化氮（NO）对疟原虫雄配子形成的影响。 方法 约氏疟原虫感染DBA/2小鼠，制备薄血膜吉氏（Giemsa）染色观察小鼠原虫血症和配子体血症水平。并通过Griess反应检测脾细胞产生的NO水平。感染第4天，实验组小鼠注射不同剂量的一氧化氮发生剂（NOC5），对照组小鼠注射NOC5前体物质，分别采集其注射前、注射后30 min和60 min的尾静脉血；感染第6天，实验组小鼠注射一氧化氮合酶抑制剂（L-NMMA），对照组小鼠分别注射D-NMMA和PBS，分别采集其注射前、注射后4 h和8 h的尾静脉血。体外培养采集的血液，观察雄配子形成。 结果 感染后第4天和第6天，小鼠脾细胞合成NO水平分别为16.5 mmol/L和30.4 mmol/L，而雄配子形成数分别为11.33和0.66；感染第4 天小鼠注射1 mg NOC5 后30 min和60 min的雄配子形成数分别为5.33和2.66，显著低于其对照组（P＜0.01）；感染第6 天小鼠注射L-NMMA后8 h的雄配子形成数为1.83，显著高于其对照组（P＜0.01）。 结论 NO可直接抑制疟原虫雄配子形成，是导致疟疾自然传播阻断现象发生的主要效应分子。

In vitro Observation on Effect of Nitric Oxide on Exflagellation of Plasmodium yoelii

Objective To observe the effect of nitric oxide (NO) on exflagellation of malaria parasite. Methods The level of parasitemia and gametocytemia in DBA/2 mice infected with Plasmodium yoelii 17XL was measured by scanning Giemsa-stained blood smears, and the NO level in culture supernatant of splenocytes was checked using Griess reaction. The mice were injected with different doses of NO donor (NOC5) on day 4 post-infection, and control mice were injected with NOC5 precursor. On day 6 post-infection, mice were injected with NOS inhibitor (L-NMMA), and control mice were injected with D-NMMA and PBS, respectively. Blood samples were collected from tail vein of mice before injection, 30 and 60 min after being injected with NOC5 and NOC5 precursor, 4 and 8 h after being injected with L-NMMA, D-NMMA, and PBS respectively. Exflagellation number of gametocytes in blood culture was counted under microscope. Results The NO level in culture supernatant of splenocytes from mice on day 4 and 6 post-infection was 16.5 mmol/L and 30.4 mmol/L, and exflagellation number was 11.33 and 0.66, respectively. The number of exflagellation in parasitized erythrocytes, obtained from mice on day 4 post-infection, was 5.33 and 2.66, respectively, 30 and 60 min after injection of 1 mg NO donor (NOC5), significantly lower than that of the control (P<0.01). The number of exflagellation in parasitized erythrocytes derived from mice on day 6 post-infection was 1.83, 8 h after the injection of NOS inhibitor (L-NMMA), which was significantly higher than that of the control (P<0.01). Conclusion NO is a major effector molecule resulting in natural transmission-blocking of malaria parasite by directly inhibiting exflagellation of male gametocytes.