Albumin enhances superoxide production in cultured microglia

✍ Scribed by Qiu-Sheng Si; Yoichi Nakamura; Kiyoshi Kataoka

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 67 KB
• Volume: 21
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/(sici)1098-1136(199712)21:4<413::aid-glia9>3.0.co;2-3

✦ Synopsis

Microglial activation and disruption of blood-brain barrier (BBB) are known to occur and contribute to neuronal damages in cerebral ischemic conditions and in some neurodegenerative diseases. To investigate whether a serum factor leaked out from circulation enhances microglial activation, we examined the effect of normal rat serum on superoxide (O 2 Ϫ ) production by cultured microglia. Microglia cultured from neonatal rat brains were studied on their O 2 Ϫ production induced by the addition of phorbol myristate acetate by a method of acetyl-cytochrome c reduction. The O 2 Ϫ production was significantly increased by the addition of 0.01% rat serum, and the maximal enhancement was observed at about 0.1% rat serum. After the serum was fractionated using a molecular sieve membrane, we observed the enhancing effect only in a greater molecular weight fraction (Ͼ50 kDa). Furthermore, three kinds of bovine serum albumin (BSA) with different purity, and human serum and plasma albumins, also enhanced O 2 Ϫ production to a similar extent to that by rat serum. However, other proteins tested showed no significant effect. The enhancement of O 2 Ϫ production by BSA was observed dose-dependently, and the effect of 50 µg/ml of purified BSA was equivalent to that of 0.1% rat serum, suggesting that albumin itself enhances O 2 Ϫ production by microglia. These results imply that albumin leaked out through impaired BBB may activate microglia and that the potentiation of O 2 Ϫ production by albumin results in the pathogenesis of neuronal damage in cerebral ischemia and some neurodegenerative diseases.