Hasiah A H, Elsheikh H A, Abdullah A S, Khairi H M, Rajion M A
Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
Vet J. 2000 Nov;160(3):267-72. doi: 10.1053/tvjl.2000.0498.
The effect of phenobarbitone against signal grass (Brachiaria decumbens) toxicity was studied in 26 male crossbred sheep. Grazing on signal grass significantly decreased the concentration of cytochrome P-450 and the activity of drug metabolizing enzymes, viz. aminopyrine-N-demethylase, aniline-4-hydroxylase, UDP- glucuronyltransferase and glutathione-S-transferase in liver and kidneys of affected sheep.Oral administration of phenobarbitone (30 mg/kg body weight) for five consecutive days before grazing on B. decumbens pasture, and thereafter, for three consecutive days every two weeks, resulted in significant increases in hepatic and renal activities of drug-metabolizing enzymes. The induction of drug metabolizing activity in sheep grazing on signal grass group was found to be lower than in animals given phenobarbitone alone. Induction by phenobarbitone provided a degree of protection against the toxic effects of B. decumbens as indicated by the delay in the appearance of signs of toxicity. Furthermore, these were much milder compared to those in the sheep not treated with phenobarbitone. The present study suggests that phenobarbitone-type cytochrome P-450 isoenzyme-induction may increase resistance against signal grass (B. decumbens) toxicity in sheep.
在26只雄性杂交绵羊中研究了苯巴比妥对臂形草（俯仰臂形草）毒性的影响。采食臂形草显著降低了受影响绵羊肝脏和肾脏中细胞色素P-450的浓度以及药物代谢酶的活性，即氨基比林-N-脱甲基酶、苯胺-4-羟化酶、UDP-葡糖醛酸基转移酶和谷胱甘肽-S-转移酶。在采食俯仰臂形草牧场之前连续五天口服苯巴比妥（30毫克/千克体重），此后每两周连续三天给药，导致肝脏和肾脏中药物代谢酶的活性显著增加。发现采食臂形草组绵羊的药物代谢活性诱导低于单独给予苯巴比妥的动物。苯巴比妥诱导提供了一定程度的保护，防止俯仰臂形草的毒性作用，这表现为毒性迹象出现的延迟。此外，与未用苯巴比妥治疗的绵羊相比，这些毒性迹象要轻得多。本研究表明，苯巴比妥型细胞色素P-450同工酶诱导可能会增加绵羊对臂形草（俯仰臂形草）毒性的抵抗力。
