Regulation of β‐nerve growth factor expression by inflammatory mediators in hippocampal cultures

Substances which regulate expression of nerve growth factor (NGF) were examined in embryonic rat: hippocampal cultures containing both neurons and glial cells. Both cell types expressed NGF mRNA when cultivated in vitro. Lipopolysaccharide, an activator of macrophages, elicited a significant increase in NGF mRNA. Interleukin‐1β evoked a similar increase in NGF mRNA which was accompanied by a rise in NGF protein. The II‐1‐induced increase was partially blocked by indomethacin, suggesting that prostaglandins might mediate this effect. Treatment of the cultures directly with prostaglandin E 2 resulted in elevated levels of both NGF mRNA and protein. Thus, agents which promote inflammatory activity appear to increase NGF expression. Moreover, a suppressor of inflammation, dexamethasone, decreased NGF expression. Our observations indicate that a variety of immunomodulators regulate NGF expression in the hippocampus.