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Berberine Inhibits the Release of Glutamate in Nerve Terminals from Rat Cerebral Cortex.

Lin TY, Lin YW, Lu CW, Huang SK, Wang SJ - PLoS ONE (2013)

Bottom Line: The inhibitory effect of berberine on glutamate release was associated with a reduction in the depolarization-induced increase in cytosolic free Ca(2+) concentration.Moreover, the inhibitory effect of berberine on evoked glutamate release was prevented in nerve terminals from mice lacking synapsin I.Together, these results indicated that berberine inhibits glutamate release from rats cortical synaptosomes, through the suppression of presynaptic Cav2.1 channels and ERK/synapsin I signaling cascade.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan ; Department of Mechanical Engineering, Yuan Ze University, New Taipei, Taiwan.

ABSTRACT
Berberine, an isoquinoline plant alkaloid, protects neurons against neurotoxicity. An excessive release of glutamate is considered to be one of the molecular mechanisms of neuronal damage in several neurological diseases. In this study, we investigated whether berberine could affect endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes) and explored the possible mechanism. Berberine inhibited the release of glutamate evoked by the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by the chelating extracellular Ca(2+) ions and the vesicular transporter inhibitor bafilomycin A1, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Inhibition of glutamate release by berberine was not due to it decreasing synaptosomal excitability, because berberine did not alter 4-AP-mediated depolarization. The inhibitory effect of berberine on glutamate release was associated with a reduction in the depolarization-induced increase in cytosolic free Ca(2+) concentration. Involvement of the Cav2.1 (P/Q-type) channels in the berberine action was confirmed by blockade of the berberine-mediated inhibition of glutamate release by the Cav2.1 (P/Q-type) channel blocker ω-agatoxin IVA. In addition, the inhibitory effect of berberine on evoked glutamate release was prevented by the mitogen-activated/extracellular signal-regulated kinase kinase (MEK) inhibitors. Berberine decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synapsin I, the main presynaptic target of ERK; this decrease was also blocked by the MEK inhibition. Moreover, the inhibitory effect of berberine on evoked glutamate release was prevented in nerve terminals from mice lacking synapsin I. Together, these results indicated that berberine inhibits glutamate release from rats cortical synaptosomes, through the suppression of presynaptic Cav2.1 channels and ERK/synapsin I signaling cascade. This finding may provide further understanding of the mode of berberine action in the brain and highlights the therapeutic potential of this compound in the treatment of a wide range of neurological disorders.

No MeSH data available.


Related in: MedlinePlus

Berberine inhibits 4-AP-induced glutamate release from rat cerebrocortical nerve terminals; this effect is due to a decrease in vesicular exocytosis.Glutamate release (+Ca2+; A) and Ca2+-independent glutamate release (-Ca2+; C) was measured under control conditions or in the presence of 10 µM berberine added 10 min prior to the addition of 4-AP. Ca2+-independent release was assayed by omitting CaCl2 and adding 300 µM EGTA 10 min prior to depolarization. B: Dose-response curves of decrease in 4-AP-evoked glutamate release in the presence of berberine. D: Glutamate release was evoked by 1 mM 4-AP in the absence and presence of 10 µM berberine and absence and presence of 10 µM DL-TBOA, or 0.1 µM bafilomycin A1. DL-TBOA or bafilomycin A1 was added 20 min before depolarization, while berberine was added 10 min before depolarization. Results are mean ± SEM of 5–6 independent experiments. ***, P<0.001 versus control group; #, P<0.05 versus DL-TBOA-treated group.
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pone-0067215-g001: Berberine inhibits 4-AP-induced glutamate release from rat cerebrocortical nerve terminals; this effect is due to a decrease in vesicular exocytosis.Glutamate release (+Ca2+; A) and Ca2+-independent glutamate release (-Ca2+; C) was measured under control conditions or in the presence of 10 µM berberine added 10 min prior to the addition of 4-AP. Ca2+-independent release was assayed by omitting CaCl2 and adding 300 µM EGTA 10 min prior to depolarization. B: Dose-response curves of decrease in 4-AP-evoked glutamate release in the presence of berberine. D: Glutamate release was evoked by 1 mM 4-AP in the absence and presence of 10 µM berberine and absence and presence of 10 µM DL-TBOA, or 0.1 µM bafilomycin A1. DL-TBOA or bafilomycin A1 was added 20 min before depolarization, while berberine was added 10 min before depolarization. Results are mean ± SEM of 5–6 independent experiments. ***, P<0.001 versus control group; #, P<0.05 versus DL-TBOA-treated group.

Mentions: 4-AP (1mM) evoked glutamate release of 7.3±0.1nmol/mg/5min from cerebral cortex synaptosomes in the presence of 1.2mM CaCl2 (Figure 1A). Preincubation with berberine (10 µM) before 4-AP addition inhibited glutamate release to 3.9±0.2nmol/mg/5min (P<0.001), without altering the basal release of glutamate (Figure 1A). The IC50 value for berberine inhibition of 4-AP-evoked glutamate release, derived from a log dose-response curve (Figure 1B), was 20 µM. Given the robust repression of evoked glutamate release seen with 10 µM berberine, this concentration was used in subsequent experiments to evaluate the mechanisms that underlie the ability of berberine to reduce glutamate release.


Berberine Inhibits the Release of Glutamate in Nerve Terminals from Rat Cerebral Cortex.

Lin TY, Lin YW, Lu CW, Huang SK, Wang SJ - PLoS ONE (2013)

Berberine inhibits 4-AP-induced glutamate release from rat cerebrocortical nerve terminals; this effect is due to a decrease in vesicular exocytosis.Glutamate release (+Ca2+; A) and Ca2+-independent glutamate release (-Ca2+; C) was measured under control conditions or in the presence of 10 µM berberine added 10 min prior to the addition of 4-AP. Ca2+-independent release was assayed by omitting CaCl2 and adding 300 µM EGTA 10 min prior to depolarization. B: Dose-response curves of decrease in 4-AP-evoked glutamate release in the presence of berberine. D: Glutamate release was evoked by 1 mM 4-AP in the absence and presence of 10 µM berberine and absence and presence of 10 µM DL-TBOA, or 0.1 µM bafilomycin A1. DL-TBOA or bafilomycin A1 was added 20 min before depolarization, while berberine was added 10 min before depolarization. Results are mean ± SEM of 5–6 independent experiments. ***, P<0.001 versus control group; #, P<0.05 versus DL-TBOA-treated group.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3686739&req=5

pone-0067215-g001: Berberine inhibits 4-AP-induced glutamate release from rat cerebrocortical nerve terminals; this effect is due to a decrease in vesicular exocytosis.Glutamate release (+Ca2+; A) and Ca2+-independent glutamate release (-Ca2+; C) was measured under control conditions or in the presence of 10 µM berberine added 10 min prior to the addition of 4-AP. Ca2+-independent release was assayed by omitting CaCl2 and adding 300 µM EGTA 10 min prior to depolarization. B: Dose-response curves of decrease in 4-AP-evoked glutamate release in the presence of berberine. D: Glutamate release was evoked by 1 mM 4-AP in the absence and presence of 10 µM berberine and absence and presence of 10 µM DL-TBOA, or 0.1 µM bafilomycin A1. DL-TBOA or bafilomycin A1 was added 20 min before depolarization, while berberine was added 10 min before depolarization. Results are mean ± SEM of 5–6 independent experiments. ***, P<0.001 versus control group; #, P<0.05 versus DL-TBOA-treated group.
Mentions: 4-AP (1mM) evoked glutamate release of 7.3±0.1nmol/mg/5min from cerebral cortex synaptosomes in the presence of 1.2mM CaCl2 (Figure 1A). Preincubation with berberine (10 µM) before 4-AP addition inhibited glutamate release to 3.9±0.2nmol/mg/5min (P<0.001), without altering the basal release of glutamate (Figure 1A). The IC50 value for berberine inhibition of 4-AP-evoked glutamate release, derived from a log dose-response curve (Figure 1B), was 20 µM. Given the robust repression of evoked glutamate release seen with 10 µM berberine, this concentration was used in subsequent experiments to evaluate the mechanisms that underlie the ability of berberine to reduce glutamate release.

Bottom Line: The inhibitory effect of berberine on glutamate release was associated with a reduction in the depolarization-induced increase in cytosolic free Ca(2+) concentration.Moreover, the inhibitory effect of berberine on evoked glutamate release was prevented in nerve terminals from mice lacking synapsin I.Together, these results indicated that berberine inhibits glutamate release from rats cortical synaptosomes, through the suppression of presynaptic Cav2.1 channels and ERK/synapsin I signaling cascade.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan ; Department of Mechanical Engineering, Yuan Ze University, New Taipei, Taiwan.

ABSTRACT
Berberine, an isoquinoline plant alkaloid, protects neurons against neurotoxicity. An excessive release of glutamate is considered to be one of the molecular mechanisms of neuronal damage in several neurological diseases. In this study, we investigated whether berberine could affect endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes) and explored the possible mechanism. Berberine inhibited the release of glutamate evoked by the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by the chelating extracellular Ca(2+) ions and the vesicular transporter inhibitor bafilomycin A1, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Inhibition of glutamate release by berberine was not due to it decreasing synaptosomal excitability, because berberine did not alter 4-AP-mediated depolarization. The inhibitory effect of berberine on glutamate release was associated with a reduction in the depolarization-induced increase in cytosolic free Ca(2+) concentration. Involvement of the Cav2.1 (P/Q-type) channels in the berberine action was confirmed by blockade of the berberine-mediated inhibition of glutamate release by the Cav2.1 (P/Q-type) channel blocker ω-agatoxin IVA. In addition, the inhibitory effect of berberine on evoked glutamate release was prevented by the mitogen-activated/extracellular signal-regulated kinase kinase (MEK) inhibitors. Berberine decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synapsin I, the main presynaptic target of ERK; this decrease was also blocked by the MEK inhibition. Moreover, the inhibitory effect of berberine on evoked glutamate release was prevented in nerve terminals from mice lacking synapsin I. Together, these results indicated that berberine inhibits glutamate release from rats cortical synaptosomes, through the suppression of presynaptic Cav2.1 channels and ERK/synapsin I signaling cascade. This finding may provide further understanding of the mode of berberine action in the brain and highlights the therapeutic potential of this compound in the treatment of a wide range of neurological disorders.

No MeSH data available.


Related in: MedlinePlus