Cholinergic involvement and synaptic dynamin 1 expression in Yokukansan-mediated improvement of spatial memory in a rat model of early Alzheimer's disease.

The aim of this study was to investigate the effect of Yokukansan (YKS) on the impairment of spatial memory and cholinergic involvement in a rat model of early-phase Alzheimer's disease (AD). In this model, rats underwent four-vessel transient cerebral ischemia and then were treated with beta amyloid oligomers injected intracerebroventricularly once daily for 7 days. These animals showed memory impairment in an eight-arm radial maze task without histological evidence of apoptosis but with a decrease in expression of hippocampal dynamin 1, an important factor in synaptic vesicle endocytosis. Oral administration of YKS for 2 weeks significantly increased the number of correct choices and decreased the number of error choices in the eight-arm radial maze task (P < 0.05). Moreover, YKS significantly increased high K⁺-evoked potentiation of acetylcholine (ACh) release (P < 0.05) and significantly increased the expression of dynamin 1 (P < 0.01) in the hippocampus. The ameliorative effect of YKS on spatial memory impairment in our rat model of early-phase AD may be mediated in part by an increase in ACh release and modulation of dynamin 1 expression, leading to improved synaptic function. Future studies will determine whether YKS is similarly useful in the treatment of memory defects in patients diagnosed with early-stage AD.

Hypothalamic 2-arachidonoylglycerol regulates multistage process of high-fat diet preferences.

BACKGROUND: In this study, we examined alterations in the hypothalamic reward system related to high-fat diet (HFD) preferences. We previously reported that hypothalamic 2-arachidonoylglycerol (2-AG) and glial fibrillary acid protein (GFAP) were increased after conditioning to the rewarding properties of a HFD. Here, we hypothesized that increased 2-AG influences the hypothalamic reward system. METHODS: The conditioned place preference test (CPP test) was used to evaluate HFD preferences. Hypothalamic 2-AG was quantified by gas chromatography-mass spectrometry. The expression of GFAP was examined by immunostaining and western blotting. RESULTS: Consumption of a HFD over either 3 or 7 days increased HFD preferences and transiently increased hypothalamic 2-AG levels. HFD consumption over 14 days similarly increased HFD preferences but elicited a long-lasting increase in hypothalamic 2-AG and GFAP levels. The cannabinoid 1 receptor antagonist O-2050 reduced preferences for HFDs after 3, 7, or 14 days of HFD consumption and reduced expression of GFAP after 14 days of HFD consumption. The astrocyte metabolic inhibitor Fluorocitrate blocked HFD preferences after 14 days of HFD consumption. CONCLUSIONS: High levels of 2-AG appear to induce HFD preferences, and activate hypothalamic astrocytes via the cannabinoid system. We propose that there may be two distinct stages in the development of HFD preferences. The induction stage involves a transient increase in 2-AG, whereas the maintenance stage involves a long lasting increase in 2-AG levels and activation of astrocytes. Accordingly, hypothalamic 2-AG may influence the development of HFD preferences.

Yokukansan enhances pentobarbital-induced sleep in socially isolated mice: possible involvement of GABA(A)-benzodiazepine receptor complex.

In the present study, we investigated the effect of the Kampo medicine Yokukansan (YKS) on pentobarbital-induced sleep in group-housed and socially isolated mice. Socially isolated mice showed shorter sleeping time than the group-housed mice. YKS (300 mg/kg, p.o.) prolonged the pentobarbital-induced sleeping time in socially isolated mice without affecting pentobarbital sleep in group-housed mice. The prolongation of sleeping time by YKS was reversed by bicuculline (3 mg/kg, i.p.) and flumazenil (3 mg/kg, i.p.), but not WAY100635. These findings suggest that the GABA(A)-benzodiazepine receptor complex, but not 5-HT(1A) receptors, is involved in the reversal effect of YKS on the decrease of pentobarbital sleep by social isolation.

Yokukansan Enhances Pentobarbital-Induced Sleep in Socially Isolated Mice: Possible Involvement of GABA(A) - Benzodiazepine Receptor Complex.

In the present study, we investigated the effect of the Kampo medicine Yokukansan (YKS) on pentobarbital-induced sleep in group-housed and socially isolated mice. Socially isolated mice showed shorter sleeping time than the group-housed mice. YKS (300 mg/kg, p.o.) prolonged the pentobarbital-induced sleeping time in socially isolated mice without affecting pentobarbital sleep in group-housed mice. The prolongation of sleeping time by YKS was reversed by bicuculline (3 mg/kg, i.p.) and flumazenil (3 mg/kg, i.p.), but not WAY100635. These findings suggest that the GABA(A) - benzodiazepine receptor complex, but not 5-HT(1A) receptors, is involved in the reversal effect of YKS on the decrease of pentobarbital sleep by social isolation.

Increment of hypothalamic 2-arachidonoylglycerol induces the preference for a high-fat diet via activation of cannabinoid 1 receptors.

The aim of the present study is to examine the relationship between preference for HFD and 2-arachidonoylglycerol (2-AG), endogenous cannabinoid. The 3-day HFD intake induced preference for HFD, which was suppressed by CB1 antagonist, O-2050. Moreover, hypothalamic 2-AG was increased after 3-day HFD intake. Our results show that preference for HFD is induced by activation of CB1 receptors via an increment of 2-AG in hypothalamus.

Effects of yokukansan on anxiety-like behavior in a rat model of cerebrovascular dementia.

Behavioral and psychological symptoms of dementia (BPSD) are commonly seen in patients with dementia. Current pharmacological approaches to treatment are inadequate, despite the availability of serotonergic agents to ameliorate anxiety, one of the symptoms of BPSD. The herbal medicine yokukansan has been demonstrated to improve BPSD in a randomized, single-blinded, placebo-controlled study. However, the mechanisms of the anxiolytic effect of yokukansan have not been clarified. There are also no reports on the anxiolytic effect of yokukansan in cerebrovascular ischemia models. In this study, we examined whether rats subjected to repeated cerebral ischemia exhibited anxiety-like behavior in a plus-maze task, a light/dark box test and an open-field task. We then investigated the effect of yokukansan on anxiety-like behavior in ischemic rats. Repeated ischemia was induced by the four-vessel occlusion method in which a 10-min ischemic episode was repeated once after 60 min. Yokukansan was orally administered once a day for 14 days from 7 days before ischemia induction. The last administration was performed 1 h before the behavioral experiments. The ischemic rats showed anxiety-like behavior in all three tasks, suggesting that this rat may be a good model for anxiety in cerebrovascular dementia. Yokukansan exhibited anxiolytic effects on the anxiety-like behavior in rats subjected to repeated cerebral ischemia, and exerted antagonistic effects on the wet-dog shakes induced by 1-(2,5-dimethoxy-4-indophenyl)-2-amino propane, a serotonin receptor (5-HT(2A)) agonist. This study revealed that yokukansan shows anxiolytic effects not only in normal animals but also in cerebrovascular model rats.

The cannabinoid 1-receptor silent antagonist O-2050 attenuates preference for high-fat diet and activated astrocytes in mice.

Endocannabinoids have been shown to activate reward-related feeding and to promote astrocytic differentiation. We investigated whether high-fat diet (HFD) intake produced a preference for HFD via an endocannabinoid-dependent mechanism. In the conditioned place preference test, the 2-week HFD-intake group showed preference for HFD and had increased expression of a marker for reactive astrocytes, glial fibrillary acid protein (GFAP), in the hypothalamus. The cannabinoid CB(1)-receptor antagonist O-2050 reduced the preference for HFD and expression of GFAP in the hypothalamus. These results suggested that HFD intake led to the development of a preference for HFD via astrocytic CB(1) receptors in the hypothalamus.

Ameliorating effects of Kangen-karyu on neuronal damage in rats subjected to repeated cerebral ischemia.

We previously reported that 21-day (14-day pre-ischemic and 7-day post-ischemic) treatment with Kangen-karyu (KGKR) improved spatial memory impairment and hippocampal neuronal death induced by repeated cerebral ischemia (2 x 10-min, 1-h interval) in rats. In the present study, we examined the effect of single and 14-day pre-ischemic KGKR treatment on neuronal damage in the same repeated cerebral ischemia model. Additionally, to determine the mechanisms of neuroprotection by KGKR at glutamatergic neurons, we examined the effects of KGKR on glutamate release induced by repeated cerebral ischemia in vivo, and on cell damage induced by both glutamate and kainate in primary cultured hippocampal neurons in vitro. The 14-day pre-ischemic KGKR (300 mg/kg, oral administration (p.o.)) treatment reduced neuronal damage and astrocyte expression induced by repeated cerebral ischemia. No effect was observed after single pre-ischemic KGKR treatment. Both single and 14-day KGKR treatment decreased glutamate release in the hippocampal CA1 region in intact rats; however, neither pre-ischemic KGKR treatment altered glutamate release during cerebral ischemia. In vitro, KGKR (100-1000 microg/mL) dose-dependently suppressed hippocampal neuronal damage induced by both glutamate (100 microM) and kainate (1 mM). These data suggest neuroprotection with KGKR requires continuous pre-ischemic treatment, and that the mechanisms of protection may be involved in inhibiting the glutamatergic receptors of the post-synaptic neurons.