PI3K negatively regulates the LPS-induced increase in NO production. The specific PI3K inhibitor wortmannin (1 μM) was administered individually 90 mins before LPS treatment (1 μg/ml), or 30 mins before pioglitazone followed by LPS 60 mins later in microglia-enriched culture, and after 48 hrs NO levels were measured. The results show that the LPS-induced NO level was significantly higher than control (p < 0.01), and that pretreatment with pioglitazone inhibits LPS-induced NO (p < 0.01). In contrast, pretreatment with wortmannin enhanced the LPS-induced increase in NO generation (p < 0.05), and this pretreatment prevented the inhibitory effect of pioglitazone on LPS-induced NO generation. Data presented are representative of three independent experiments (n = 3).). (**p < 0.01 vs. control, #p < 0.05 vs. LPS, ##p < 0.01 vs. LPS, &&p < 0.01 vs. Piog plus LPS).