黃芩抽出物對脂多醣體所誘發的腎絲球腎炎的療效研究

Study of the extracts of Scutellaria baicalensis on lipopolysaccharide-induced glomerulonephritis

姚竹凌(Chu-Ling Yao)

指導教授 ： 邱慧芬 ； 周志中

高雄醫學大學/醫學院/醫學研究所/碩士(2006年)

摘要

敗血性休克（septic shock）在臨床上是一個很嚴重的疾病，其死亡率高達50%以上。有文獻報告指出敗血性休克在腎臟組織中腎絲球損傷（glomerular injury）造成腎絲球（glomeruli）與腎小管（tubulointerstitium）有較多的發炎細胞的浸潤（infiltration）。在動物實驗中研究顯示注射低劑量的脂多醣（lipopolysaccharide, LPS）也會造成實驗性的腎絲球腎炎（glomerulonehritis）的症狀。
中藥黃芩（Scutellaria baicalensis）已知具有抗發炎、解熱、抗病毒、抗癌、抗氧化、清除自由基、抗凝血、抗過敏等藥理作用。先前在離體（in vitro）實驗中，已證明黃芩的主成分之一黃芩素（baicalen）在RAW264.7巨噬細胞對LPS所活化誘發型一氧化氮合成酶（inducible nitric oxide synthesis, iNOS）、第二型環氧化酶（cyclooxygenases-2, COX-2）和細胞激素（cytokine）的表現皆有明顯抑制。而黃芩抽出物對LPS所誘發的腎絲球腎炎的作用至今尚無相關研究報告。
因此，本實驗之主要目的就是評估黃芩的水萃液對於LPS誘發小鼠腎絲球腎炎動物模式的療效。首先，我們以腹腔每日注射LPS（4.8mg/kg/day）連續2週以誘發C57鼠產生腎絲球腎炎。之後，我們每日口服給予黃芩（150 mg/kg/day）2週以評估其療效及可能作用機轉。
結果顯示，黃芩治療組與未投與黃芩治療組相比較發現黃芩治療組腎絲球肥大和腎間質細胞的浸潤明顯改善。此外黃芩治療組明顯減少尿素氮（serum blood urea nitrogen）、肌酸酐值（creatinine）、尿蛋白、脊髓過氧化酵素（myeloperoxidase）的活性（嗜中性白血球在發炎組織的聚集和增加指標）、尿液與血液亞硝酸鹽/硝酸鹽（nitrite/nitrate）的含量、血清前列腺素E2（prostaglandin E2）、尿液中的8異前列腺素F2?恁]8-iso-prostaglandin F2a（其為脂質過氧化物的特殊指標）。而黃芩治療組明顯增加細胞激素介白素-10（Interleukin-10, IL-10）使得抗發炎訊息增強，另外黃芩治療組明顯降低腎臟組織iNOS、COX-2的蛋白質表現。
總結，本實驗證明投予黃芩的水萃液能有效的改善LPS所誘發腎絲球腎炎鼠的腎功能及腎組織的病理變化，其作用機轉可能包括（1）抑制NO / iNOS和PGE2 / COX-2的路徑（2）抑制腎炎組織中嗜中性白血球浸潤（3）抑制自由基過度的生成（4）增加抗發炎性細胞激素IL-10。期望經由這些研究結果，能提供黃芩在未來臨床應用在治療腎絲球腎炎方向提供有價值的訊息。

關鍵字

黃芩 ； 脂多醣 ； 腎絲球腎炎 ； 一氧化氮

並列摘要

Septic shock is an important clinical issue. The mortality is over 50%. Previous reports proposed that septic shock leads to the infiltration of inflammatory cells in glomeruli and the tubulointerstitium of the kidney. However, are not entirely clear. Studies have also shown that this greatly enhances the severity of glomerular injury in small doses of lipopolysaccharide (LPS)-induced of experimental glomerulonehritis.
Scutellaria baicalensis (SB), is widely used in the traditional Chinese herbal medicine for its anti-inflammatory, anti-pyretic, anti-HIV, anti-tumor, antioxidant, free radical scavenging, anti-platelet aggregation and anti-hypersensitivity effects. Our previous in vitro study demonstrated that baicalen, one of flavonid compounds, isolated from SB could inhibit expression of inducible nitric oxide synthesis (iNOS), cyclooxygenases-2 (COX-2) and cytokine in LPS-induced mouse marcrophage (RAW 264.7 cell line).
Thus, the aim of this study was to investigate whether the extracts of SB have beneficial effect in LPS-induced GN and further evaluate the possible mechanisms involved. First, we evaluate the effect on GN induced by intraperitoneally (i.p.) administration of LPS (4.8mg/kg/day) for 2 weeks in C57BL/6J mice. Then, the water extract of SB (150 mg/kg/day, p.o.) was administrated for 2 weeks in LPS-induced glomrerulnephritis mice.

Our results showed that SB alleviated glomerular and mesangial cell proliferation of the histological examination in LPS-treated mice. Similarly, SB reduced the serum blood urea nitrogen, creatinine, urine protein, the nitrite/nitrate level in urine and serum, serum prostaglandin E2 level, urine 8-iso-PGF2a (the peroxidation of membrane lipids by free radicals and reactive oxygen species), renal myeloperoxidase (MPO) (neutrophil infiltration marker) activity, and renal iNOS; COX-2 expression in LPS-induced mice. Furthermore, SB also significantly increased Interleukin-10 (IL-10), that is a cytokine with anti-inflammatory.
In conclusion, the results indicated that the water extract of SB significantly alleviated renal function and histological examination. The possible mechanisms may be associated with (1) decreased NO/iNOS; PGE2/COX-2 pathway (2) decreased neutrophil infiltration (3) reduced free radicals formation (4) improved anti-inflammatory cytokines formation including IL-10 ?nin LPS-injected mice. Hopefully, the Scutellaria baicalensis may be an effective therapeutic intervention for anti- glomerulonehritis.

並列關鍵字

Scutellaria baicalensis ； lipopolysaccharide ； glomrerulonephritis ； nitric oxide.

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