Houttuyniae Herba Attenuates Kainic Acid-Induced Neurotoxicity via Calcium Response Modulation in the Mouse Hippocampus.

Epilepsy is a complex neurological disorder characterized by the repeated occurrence of electrical activity known as seizures. This activity induces increased intracellular calcium, which ultimately leads to neuronal damage. Houttuyniae Herba, the aerial part of Houttuynia cordata, has various pharmacological effects and is widely used as a traditional herb. In the present study, we evaluated the protective effects of Houttuyniae Herba water extract on kainic acid-induced neurotoxicity. Kainic acid directly acts on calcium release, resulting in seizure behavior, neuronal damage, and cognitive impairment. In a rat primary hippocampal culture system, Houttuyniae Herba water extract significantly protected neuronal cells from kainic acid toxicity. In a seizure model where mice received intracerebellar kainic acid injections, Houttuyniae Herba water extract treatment resulted in a lower seizure stage score, ameliorated cognitive impairment, protected neuronal cells against kainic acid-induced toxicity, and suppressed neuronal degeneration in the hippocampus. In addition, Houttuyniae Herba water extract regulated increases in the intracellular calcium level, its related downstream pathways (reactive oxygen species production and mitochondrial dysfunction), and calcium/calmodulin complex kinase type II immunoreactivity in the mouse hippocampus, which resulted from calcium influx stimulation induced by kainic acid. These results demonstrate the neuroprotective effects of Houttuyniae Herba water extract through inhibition of calcium generation in a kainic acid-induced epileptic model.

The effects of a standardized Acanthopanax koreanum extract on stress-induced behavioral alterations in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: The roots and stem bark of Acanthopanax koreanum Nakai (Araliaceae), a well-known herbal medicine in Jeju Island, Korea, has been used as a tonic agent in treating stress-related states. Despite its popular application, the anti-anxiety or anti-depressive action of Acanthopanax koreanum is not yet known. AIM OF THE STUDY: This study aimed to determine the effects of Acanthopanax koreanum on stress-induced behavioral alterations such as anxiety and depression. MATERIALS AND METHODS: Mice in the acute stress group were exposed to immobilization stress for 2h followed by electric foot shocks (0.5 mA in 1 s duration with a 10 s inter-shock interval) for 2 min, while sub-chronically stressed mice were exposed to these stresses for 2 weeks, once per day. 70% ethanolic extract of Acanthopanax koreanum (EEAK) (25, 50, 100, or 200 mg/kg) was administered once or sub-chronically (for 2 weeks) 1h prior to stress induction. Anxiety- or depression-like behavioral changes were evaluated using the elevated plus-maze (EPM) test and the forced swimming test (FST) a day after the final stress induction. Corticosterone levels and spleen weight were measured after conducting all the behavioral assays. The numbers of BrdU- or DCX-immunopositive cells in the hippocampal region of sub-chronically stressed mice were measured 2 days after EEAK treatment. RESULTS: The percentage of time spent in the open arms was decreased in both the acutely and chronically stressed mice. In the FST, the immobility time was increased by only chronic stress, but not by acute stress. Acute or sub-chronic administration of EEAK significantly prevented the anxiety- or depression-like behavioral changes caused by stress. EEAK also attenuated stress-induced decrease and increase of spleen weight and corticosterone levels, respectively. Furthermore, the sub-chronic administration of EEAK (100 or 200 mg/kg, for 2 weeks) increased the number of BrdU-, doublecortin-, and neuropeptide Y-positive cells in the hippocampal region of the sub-chronically stressed mice. CONCLUSION: EEAK attenuated the behavioral and biochemical changes in acute or sub-chronic stressed mice. These results suggest the therapeutic potential of Acanthopanax koreanum for the treatment of stress-related neuropsychiatric disorders including anxiety disorders or major depressive disorder.

The ameliorating effects of 5,7-dihydroxy-6-methoxy-2(4-phenoxyphenyl)-4H-chromene-4-one, an oroxylin A derivative, against memory impairment and sensorimotor gating deficit in mice.

We previously reported that oroxylin A, a γ-aminobutyric acid A (GABAA) receptor antagonist, ameliorates drugs-induced memory impairments. We synthesized several oroxylin A derivatives in efforts to find a substance that has pro-cognitive effects as well as improves sensorimotor gating. The aim of the present study is to investigate the effect of a novel oroxylin A derivative, 5,7-dihydroxy-6-methoxy-2(4-phenoxyphenyl)-4H-chromene-4-one (DMPC), on pharmacological models of schizophrenia, which exhibit memory impairment and sensorimotor gating deficit. Memory impairment was induced by scopolamine, a muscarinic receptor antagonist, or MK-801, an N-methyl-D-aspartate receptor antagonist. Sensorimotor gating deficits were induced by MK-801 and measured by prepulse inhibition (PPI) of the acoustic startle response task. DMPC treatment (20 mg/kg) significantly attenuated scopolamine- or MK-801-induced memory impairment and it even enhanced cognitive performance of normal animals. Furthermore, DMPC significantly ameliorated MK-801-induced PPI deficits in the acoustic startle response task. In an in vitro study, DMPC (20 µM) inhibited intracellular Cl(-) influx induced by muscimol, a selective GABAA receptor agonist. These results suggest that DMPC would be a potential candidate for alleviating cognitive dysfunction and sensorimotor gating deficits in schizophrenia, and that its effects may be mediated, in part, via blockade of the GABAergic neurotransmitter system.