内毒素、IL-1β对家兔下丘脑神经细胞内游离钙浓度的影响

Intracellular calcium alterations induced by endotoxin and IL-1β in rabbit hypothalamic neurons

目的 :研究内毒素 (ET)性发热家兔下丘脑神经细胞内游离钙 ([Ca2 +]i)浓度变化及ET、白介素- 1β(IL - 1β)对正常家兔离体下丘脑神经细胞 [Ca2 +]i浓度的影响。方法 :采用荧光分光光度法 ,应用钙离子探针 (Fura - 2 /AM) ,检测 [Ca2 +]i浓度。结果 :(1)微量ET(2ng/mL)使正常家兔下丘脑神经细胞内 [Ca2 +]i浓度显著升高 ;ET性发热家兔下丘脑神经细胞 [Ca2 +]i水平也显著高于对照组 ;(2 ) 3种剂量IL - 1β(10 0、5 0 0、10 0 0ng/mL)均未能明显影响下丘脑神经细胞 [Ca2 +]i浓度。结论 :(1)低Ca2 +参与ET性发热体温调节的作用部位 ,可能不是在下丘脑神经细胞内 ;(2 )ET引起下丘脑神经细胞 [Ca2 +]i浓度变化 ,不是通过IL - 1β直接引起。

AIM: To investigate intracellular free calcium ([Ca 2+ ]i ) alterations in hypothalamus of febrile rabbits induced by endotoxin (ET), and compare with the effect of ET and IL-1β on [Ca 2+ ]i in hypothalamic neurocytes from normothermia rabbits. METHOD: The concentration of [Ca 2+ ]i was determined by using spectrofluorometer and fluorescent Ca 2+ probe fura-2 /Am. RESULTS: 1. A minute dose of ET (2 ng/mL) induced a significant rise in [Ca 2+ ]i in hypothalamic neurocytes from normothermia rabbits. The rise in [Ca 2+ ]i in hypothalamic neurocytes from febrile rabbits induced by intravenous injection of ET was also observed. 2. In hypothalamic neurocytes from normotheria rabbits, IL-1β failed to affect [Ca 2+ ]i at concentrations of 100, 500, 1 000 ng/mL, respectively. CONCLUSION:The action site of low concentration of calcium that plays a regulatory role during fever seems unlikely to be in cytosolic compartment of hypothalamic neurons. The change of [Ca 2+ ]i in hypothalamic neurocytes by ET can not be considered the direct effect of IL-1β.