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Regulation of beta-nerve growth factor expression by inflammatory mediators in hippocampal cultures
W J Friedman1, L Lärkfors, C Ayer-LeLievre
1Department of Medical Chemistry II, Karolinska Institute, Stockholm, Sweden.
Abstract:
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-1 beta evoked a similar increase in NGF mRNA which was accompanied by a rise in NGF protein. The Il-1-induced increase was partially blocked by indomethacin, suggesting that prostaglandins might mediate this effect. Treatment of the cultures directly with prostaglandin E2 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.
Insights
Inflammatory agents like Interleukin-1 beta increase nerve growth factor (NGF) expression in rat hippocampal cultures. Dexamethasone, an anti-inflammatory drug, reduces NGF levels, indicating immune system regulation of NGF.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Nerve growth factor (NGF) is crucial for neuronal survival and function.
- The regulation of NGF expression in the hippocampus, particularly by immune factors, is not fully understood.
Purpose of the Study:
- To investigate the role of immunomodulators in regulating nerve growth factor (NGF) expression in embryonic rat hippocampal cultures.
- To determine if inflammatory mediators influence NGF mRNA and protein levels.
Main Methods:
- Primary cultures of embryonic rat hippocampal neurons and glial cells were utilized.
- NGF mRNA and protein levels were quantified following treatment with various substances.
- Substances included lipopolysaccharide, Interleukin-1 beta, indomethacin, prostaglandin E2, and dexamethasone.
Main Results:
- Both neurons and glial cells expressed NGF mRNA in vitro.
- Lipopolysaccharide and Interleukin-1 beta significantly increased NGF mRNA levels.
- Interleukin-1 beta also elevated NGF protein levels, an effect partially mediated by prostaglandins.
- Prostaglandin E2 directly increased NGF mRNA and protein, while dexamethasone decreased NGF expression.
Conclusions:
- Immune system modulators, including inflammatory agents, play a significant role in regulating NGF expression in the hippocampus.
- Prostaglandins may mediate the effects of Interleukin-1 beta on NGF.
- These findings highlight a link between inflammation and neurotrophic factor regulation.