[Effects of chelation therapy with succimer in young rabbits of moderate lead poisoning]

To explore the effect of chelation therapy with succimer (DMSA) in male rabbits of moderate lead poisoning during juvenile stage.

Twenty-four 45-day-old male New Zealand rabbits were randomly divided into three groups (therapy group, TG; positive control group, PG and negative control group, NG, n=8). The TG and PG were orally exposed to lead acetate (5 mg x kg(-1) x d(-1)) for 6 weeks. Rabbits in TG were orally supplied DMSA 1050 mg/m2 in the first week and 700 mg/m2 in the next two weeks, while the other two groups wren't blood and urinary samples of all rabbits were collected per week. The tissues and organs of all rabbits were collected after 12 weeks. The blood lead levels (BLLs) were determined by atomic absorption spectrometer. The urine lead levels and the lead contents of tissue and organ were determined by inductively coupled plasma-mass spectrometry. Histopathology of tissue and organ was observed by light microscope.

Compared with PG, the lead level in the morning urine of TG with DMSA chelating was increased significantly. The level was peaked at (1246.96 +/- 157.91) microg/L on the first day after chelating. While the base line was (40.97 +/- 1.77) microg/L before chelating. Meanwhile, the BLLs were sharply declined from (429.63 +/- 10.82) microg/L to (238.50 +/- 11.82) microg/L. The urine lead levels of TG decreased through the 3-week chelating and 3-week discontinuation. The urine lead levels of these two groups were significantly different (F=2934.35, P<0.01). Compared to each two groups in these three groups, there were significant difference (P<0.01). The authors found the reversion of BLLs in first week after stop chelating. The BLLs of PG presented the slow course of declining in the same time, were (135.50 +/- 7.09) microg/L, very close to the level of TG for (149.88 +/- 11.39) microg/L. Compared with treatment discontinuation for 3 weeks, the urine lead levels and the body weight gain of the therapy group increased more than that of PG, and the BLLs and the lead concentrations in tissues and organs decreased more than that of PG, and histopathology in the liver tissues and testicle tissues were improved.

DMSA chelating for the rodent models of moderate lead poisoning might reduce the BLLs and soft tissue lead contents quickly and effectively, decrease toxic effects of lead in a short period of time, thus alleviate the impairment of lead poisoning on tissues and organs by decreasing lead burden, and bring out improvement on the growth retardation caused by lead poisoning.