Ethanol Extract of Bupleurum falcatum Improves Functional Recovery by Inhibiting Matrix Metalloproteinases-2 and -9 Activation and Inflammation after Spinal Cord Injury

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that degrade the extracellular matrix and other extracellular proteins. Upregulation of MMPs activity is known to be required for the inflammatory cell infiltration after spinal cord injury (SCI) and most likely contributes to early blood spinal barrier disruption and inflammation, thereby leading to the impairment of functional recovery. Here, we examined the effect of ethanol extract of Bupleurum falcatum (BF) on functional recovery by inhibiting MMP-2 and -9 activation and inflammation after SCI. Rats received a moderate, weight-drop contusion injury to spinal cord were administered orally with BF at a dose of 100 mg/kg for 14 d and functional recovery was measured by Basso-Beattie-Bresnahan locomotor open field behavioral rating test, inclined plane test and foot print analysis. To examine the neuroprotective effect of BF, TUNEL staining and counting were also performed. In addition, the expression and/or activation of MMP-2, MMP-9 and inflammatory mediators such as TNF-alpha, IL-1beta, COX-2, and iNOS were examined by RT-PCR and gelatin zymography using spinal cord tissue from 1 d after injury. Our data showed that BF significantly inhibited the expression and activation of both MMP-2 and MMP-9 after SCI. The mRNA expressions of TNF-alpha, IL-1beta, COX-2, and iNOS were also significantly attenuated by BF. Furthermore, BF reduced apoptotic cell death at 1 d after injury, thereby significantly reduced lesion volume and improved functional recovery. Taken together, these results suggest that BF can be used as a potential therapeutic agent for treating acute spinal injury.

Effect of Fluoxetine on the Induction of Long-term Potentiation in Rat Frontal Cortex

Serotonin (5-hydroxytroptamine, 5-HT) has been shown to affect the induction of long-term potentiation (LTP) in the cortex such as the hippocampus, the visual cortex and the prefrontal cortex. Fluoxetine, as a selective serotonin reuptake inhibitor, is used in the management of a wide variety of psychological diseases. To study the effect of fluoxetine on the induction of LTP, we recorded the field potential in layer II/III of the frontal cortex from 3-wk-old. LTP was induced in horizontal input by theta burst stimulation (TBS). TBS with two-folds intensity of the test stimulation induced LTP, which was blocked by application of D-AP5 (50microM), an NMDA receptor antagonist. Whereas bath application of 5-HT (10microM) inhibited the induction of LTP, treatment with the 5-HT depleting agent, para-chloroamphetamine (PCA, 10microM), for 2hr did not affect the induction of LTP. Bath application of fluoxetine (1, 3, and 10microM) suppressed the induction of LTP in concentration-dependent manner, however, fluoxetine did not inhibit the induction of LTP in 5-HT-depleted slices. These results indicate that fluoxetine may inhibit the induction of LTP by modulating serotonergic mechanism in the rat frontal cortex.