Taurine Counteracts the Suppressive Effect of Lipopolysaccharide on Neurogenesis in the Hippocampus of Rats
Neurogenesis has been generally accepted to happen in the subventricular zone lining the lateral ventricular and subgranular zone (SGZ) in the hippocampus of adult mammalian brain. Recent studies have reported that inflammatory stimuli, such as injection of lipopolysaccharide (LPS), impair neurogenesis in the SGZ. Taurine, a sulfur-containing β-amino acid, is a major free intracellular amino acid in many tissues of mammals and having various supplementary effects on the mammalian body functions including the brain. Recently, it has been also reported that taurine levels in the brain significantly increase under stressful conditions. The present study was aimed to evaluate the possible beneficial effects of taurine on the neurogenesis in the SGZ under the condition of acute inflammatory stimuli by LPS. Adult male rats were intraperitoneally injected with taurine once a day for 39 days. Twenty-four hours before the animals were sacrificed on the last day of taurine treatment, LPS was injected simultaneously with bromodeoxyuridine (BrdU). Immunohistochemistry for BrdU, Ki67, and Iba-1 in the brain was performed, and serum levels of TNF-α and IL-1β 2 h after LPS injection were determined. The results showed that LPS significantly decreased the number of immunoreactive cells for both BrdU and Ki67 in the SGZ, while increased that for Iba-1, all of which were restored by taurine administration. Meanwhile, the serum concentrations of TNF-α and IL-1β were significantly increased, which were significantly attenuated by taurine administration. These results suggest that taurine effectively maintains neurogenesis in the SGZ under the acute infectious condition by attenuating the increase of microgliosis in the hippocampus as well as proinflammatory cytokines in the peripheral circulation.
KeywordsDentate Gyrus Newborn Neuron Subgranular Zone Taurine Level Adult Mammalian Brain
Central nervous system
Tumor necrosis factor-α
This work was supported in part by the project of JSPS Fellowship for Researcher in JAPAN (2010 long term) to GW and a Grant-in-Aid for Scientific Research (23228004) from the JSPS to MN.
- Chung DW, Yoo KY, Hwang IK, Kim DW, Chung JY, Lee CH, Choi JH, Choi SY, Youn HY, Lee IS, Won MH (2010) Systemic administration of lipopolysaccharide induces cyclooxygenase-2 immunoreactivity in endothelium and increases microglia in the mouse hippocampus. Cell Mol Neurobiol 30:531–541PubMedCrossRefGoogle Scholar
- Gailard PJ, Voorwinden LH, Nielsen JL, Ivanov A, Atsumi R, Engman H, Ringborn C, de Boer AG, Breimer DD (2001) Establishment and functional characterization of an in vitro model of the blood-brain barrier, comprising a co-culture of brain capillary endothelial cells and astrocytes. Eur J Pharm Sci 12:215–222CrossRefGoogle Scholar
- Kuboyama N, Sato Y, Saito T, Abiko Y (2007) Stimulation of TNF-α, IL-1β and IL-6 levels in rat serum by actinobacillus actinomycetemcomitans LPS challenge. Med Biol 151:21–26Google Scholar
- Ramon y Cajal S (1913) Degeneration and regeneration of the nervous system. Oxford Univ. Press, LondonGoogle Scholar