半胱胺酸對鉛中毒小白鼠之影響

Abstract

本實驗在研究含硫胺基酸——半胱胺酸(Cysteine, Cys.)對鉛中毒小白鼠之影響。將剛出生之ICR種系小白鼠用含鉛（醋酸鉛）500 ppm之飲水處理，斷奶前餵給母鼠，斷奶後由幼鼠自行攝取。四週後檢查，小白鼠已有明顯之鉛中毒。第五週起，停止鉛處理，以不同劑量之Cys.(0,25,50,100,400及800毫克/公斤)由腹腔注射處理，每兩週三次。對於鉛中毒小白鼠(PbM)，在第六週，Cys.劑量為800毫克/公斤（用Cys. 800-6表示）時，可使5-胺基-4-酮戊酸脫水?(δ-Aminolevulinic acid dehydratase, ALAD)之活性?升。在Cys.400-6下，血容比(Hematocrit, Hct)也?升。血紅素(Hemoglobin，Hb)在Cys.50-6及Cys.100-8下也有?升現象，但在高劑量(Cys.400-8及Cys.800-8)下，反而降低。對正常小白鼠(OPbM)而言，Hb在Cys.25-6, Cys.50-6及Cys.100-6下，有升高之現象。Hct在Cys.800-6下則有降低之結果。Cys.可抑制OPbM及PbM之血清，肝及腎臟之酸性磷酸酯解?(Acid phosphatase，AcPase)之活性，也可抑制PbM血清及肝臟之鹼性磷酸酯解?(Alkaline phosphatase, AlPase)之活性。但不論OPbM或PbM, Cys.可提高腎臟AlPase之活性。Cys.亦可提高OPbM血清AlPase之活性。 因此，Cys.在適當的劑量及處理時間下，可以改善血液中鉛中毒的一些症狀。但同時也影響血清、肝及腎臟內AlPase及AcPase之活性。

The effect of a sulfur-containing amino acid, cysteine, on lead toxicity was investigated in 4-week-old to 8-week-old ICR strain mice. Neonatal mice were lactated by lead-treated dams receiving normal diet and drinking water containing 500 ppm of lead acetate from the day of parturition. After weanling (about 3 weeks old), the pups were supplied with the same water as their mothers' for one more week. After 4 weeks treatment, the mice were intoxicated obviously, including the decrease in the hematocrit (Hct) and the activity of δ-aminolevulinic acid dehydratase (ALAD) and changes in some other parameters examined. From the 5th week to the 8th week, all the normal and lead-treated mice (OPbM and PbM) were provided with tap water and subjected to i.p. injections of various doses of cysteine (0, 25, 50, 100, 400 and 800 mg/kg of body weight, in 0.2 ml distilled water) three times every two weeks. In PbM, the activity of ALAD and Hct were increased at Cys.800-6 (i.e. the dose of cysteine was 800 mg/kg, in 6-week-old mice) and Cys.400-6 respectively. At Cys.50-6 and Cys.100-8, the hemoglobin (Hb) concentration was raised, but at Cys.400-8 and Cys.800-8, it was decreased. In OPbM, the increase in the Hb concentration was also observed at Cys.25-6, Cys.50-6 and Cys.100-6. Nevertheless, the Hct was decreased at Cys.800-6. Cysteine inhibited the alkaline phosphatase (AlPase) activities of the serum and the liver in PbM, and the acid phosphatase (AcPase) activities of the serum, the liver and the kidney in both OPbM and PbM. Cysteine, however, enhanced the activities of the kidney AlPase in both OPbM and PbM and the activity of the serum AlPase in OPbM. Thus, some of the deleterious effects on hematological changes in lead intoxication might be ameliorated by using proper doses of cysteine for a proper time. However, the activities of AlPase and AcPase of the serum, the liver and the kidney might be affected simultaneously.