Preventive effect of chotosan, a Kampo medicine, on transient ischemia-induced learning deficit is mediated by stimulation of muscarinic M1 but not nicotinic receptor

Properties, Pharmacology, and Pharmacokinetics of Active Indole and Oxindole Alkaloids in Uncaria Hook

Uncaria Hook (UH) is a dry stem with hook of Ucaria plant and is contained in Traditional Japanese and Chinese medicine such as yokukansan, yokukansankachimpihange, chotosan, Gouteng-Baitouweng, and Tianma-Gouteng Yin. UH contains active indole and oxindole alkaloids and has the therapeutic effects on ailments of the cardiovascular and central nervous systems. The recent advances of analytical technology led to reports of detailed pharmacokinetics of UH alkaloids. These observations of pharmacokinetics are extremely important for understanding the treatment’s pharmacological activity, efficacy, and safety. This review describes properties, pharmacology, and the recently accumulated pharmacokinetic findings of UH alkaloids, and discusses challenges and future prospects. UH contains major indole and oxindole alkaloids such as corynoxeine, isocorynoxeine, rhynchophylline, isorhynchophylline, hirsuteine, hirsutine, and geissoschizine methyl ether (GM). These alkaloids exert neuroprotective effects against Alzheimer’s disease, Parkinson’s disease, and depression, and the mechanisms of these effects include anti-oxidant, anti-inflammatory, and neuromodulatory activities. Among the UH alkaloids, GM exhibits comparatively potent pharmacological activity (e.g., agonist activity at 5-HT_1A receptors). UH alkaloids are absorbed into the blood circulation and rapidly eliminated when orally administered. UH alkaloids are predominantly metabolized by Cytochrome P450 (CYP) and converted into various metabolites, including oxidized and demethylated forms. Regarding GM metabolism by CYPs, a gender-dependent difference is observed in rats but not in humans. Several alkaloids are detected in the brain after passing through the blood–brain barrier in rats upon orally administered. GM is uniformly distributed in the brain and binds to various channels and receptors such as the 5-HT receptor. By reviewing the pharmacokinetics of UH alkaloids, challenges were found, such as differences in pharmacokinetics between pure drug and crude drug products administration, food-influenced absorption, metabolite excretion profile, and intestinal tissue metabolism of UH alkaloids. This review will provide readers with a better understanding of the pharmacokinetics of UH alkaloids and their future challenges, and will be helpful for further research on UH alkaloids and crude drug products containing UH.

Cognitive Dysfunction in a Mouse Model of Cerebral Ischemia Influences Salivary Metabolomics

Vascular dementia, caused by cerebrovascular disease, is associated with cognitive impairment and reduced hippocampal metabolite levels. Specifically, cognitive impairment can be induced by decreased hippocampal brain-derived neurotrophic factor (BDNF) expression. The development of low or non-invasive biomarkers to characterize these diseases is an urgent task. Disturbance of metabolic pathways has been frequently observed in cognitive impairment, and salivary molecules also showed the potentials to reflect cognitive impairment. Therefore, we evaluated salivary metabolic profiles associated with altered hippocampal BDNF expression levels in a cerebral ischemia mouse model using metabolomic analyses. The effect of tacrine (a cholinesterase inhibitor) administration was also examined. The arteries of ICR mice were occluded with aneurysm clips to generate the cerebral ischemia model. Learning and memory performance was assessed using the elevated plus maze (EPM) test. Hippocampal and blood BDNF levels were quantified using an enzyme-linked immunosorbent assay. Glutamate decarboxylase 1 (GAD1) mRNA expression, is associated with cognitive impairment, was quantified by a real-time polymerase chain reaction. The EPM test revealed impaired spatial working memory in the cerebral ischemia mouse model; tacrine administration ameliorated this memory impairment. Cerebral ischemia suppressed GAD1 expression by decreasing hippocampal BDNF expression. In total, seven salivary metabolites, such as trimethylamine N-oxide and putrescine, were changed by cognitive impairment and tacrine administration. Our data suggest that salivary metabolite patterns were associated with cognitive function.

Choto-san versus placebo for patients with dementia: systematic review and meta-analysis

BACKGROUND

Choto-san is a traditional medicine used for hypertension and headaches in Japan and China. Some studies have shown its effectiveness in the treatment of dementia. The present review aimed to assess the effectiveness and acceptability of Choto-san in the treatment of adults with cognitive impairment.

METHODS

We included randomized controlled trials comparing Choto-san with placebo for patients with dementia or mild cognitive impairment.

RESULTS

Three randomized controlled trials evaluating 219 participants were included. Two were studies on vascular dementia, and the other was on Alzheimer's dementia. There was no difference between Choto-san and placebo in terms of short-term dichotomous judgement of improvement, but Choto-san was more effective than placebo in terms of short-term improvement of cognitive function as measured by continuous outcomes. Also, dropouts judged it to be acceptable. However, the results were imprecise and/or heterogeneous. The number of participants included in the analysis was small (n = 199 in the primary analysis) and sometimes inconsistent, as indicated by the large I ² (72% in the primary analysis).

CONCLUSION

Low-quality evidence was suggestive of Choto-san's efficacy for vascular dementia, but the present results may be overestimated. Studies with a larger sample size and conducted over longer periods should be performed. Regardless, Choto-san can be one of the choices for the treatment of vascular dementia as it is well tolerated.

Sigma 1 receptor activation regulates brain-derived neurotrophic factor through NR2A-CaMKIV-TORC1 pathway to rescue the impairment of learning and memory induced by brain ischaemia/reperfusion

RATIONALE

Sigma-1 receptor (Sig-1R) agonists showed anti-amnesic properties in Alzheimer's disease models and anti-inflammatory properties in cerebrum ischaemia models. The agonist of Sig-1R was reported to up-regulate brain-derived neurotrophic factor (BDNF) levels in the hippocampus of mice. Here, we investigate whether the activation of Sig-1R attenuates the learning and memory impairment induced by ischaemia/reperfusion and how it affects the expression of BDNF.

OBJECTIVES

Bilateral common carotid artery occlusion (BCCAO) was induced for 20 min in C57BL/6 mice.

MATERIALS AND METHODS

Sig-1R agonist, PRE084, sigma 1/2 non-selective agonist, DTG, Sig-1R antagonist and BD1047 were injected once daily throughout the experiment. Behavioural tests were performed from day 8. On day 22 after BCCAO, mice were sacrificed for biochemical analysis.

RESULTS

PRE084 and DTG ameliorated learning and memory impairments in the Y maze, novel object recognition, and water maze tasks and prevented the decline of synaptic proteins and BDNF expression in the hippocampus of BCCAO mice. Furthermore, PRE084 and DTG up-regulated the level of NMDA receptor 2A (NR2A), calcium/calmodulin-dependent protein kinase type IV (CaMKIV) and CREB-specific co-activator transducer of regulated CREB activity 1 (TORC1). Additionally, the effects of PRE084 and DTG were antagonised by the co-administration of BD1047.

CONCLUSIONS

Sig-1R activation showed an attenuation in the ischaemia/reperfusion model and the activation of Sig-1R increased the expression of BDNF, possibly through the NR2A-CaMKIV-TORC1 pathway, and Sig-1R agonists might function as neuroprotectant agents in vascular dementia.

Ameliorative effects of yokukansan on behavioral deficits in a gerbil model of global cerebral ischemia

The aim of this study was to investigate the neuroprotective effects of yokukansan, a traditional Kampo medicine, on the behavioral dysfunction induced by cerebral ischemia/reperfusion injury in gerbils. Gerbils were treated with yokukasan by oral gavage for 30 days, once per day, until the day before induction of ischemia, which was induced by occluding the bilateral common carotid artery for 5 min. The effects of yokukansan (50, 100 and 300 mg/kg) were examined by measuring neuronal damage and behavioral deficits (locomotor activity, 8-arm radial maze task). The anti-inflammatory and anti-oxidant properties of yokukansan were also examined. Administration of yokukansan at 300 mg/kg significantly reduced hippocampal neuronal death after brain ischemia, inhibited the ischemia-induced inflammatory response and DNA oxidative damage. Yokukansan also reduced ischemia-induced locomotor hyperactivity and improved memory impairment. These findings suggest that yokukansan can inhibit the inflammatory response, oxidative damage and subsequent neuronal death induced by cerebral ischemia/reperfusion injury, and also can contribute to improvement in neurological deficits following such injury.

Kampo formulations, chotosan, and yokukansan, for dementia therapy: existing clinical and preclinical evidence

Cognitive deficits and behavioral and psychological symptoms of dementia (BPSD) are typical features of patients with dementia such as Alzheimer's disease (AD), vascular dementia (VD), and other forms of senile dementia. Clinical evidence has demonstrated the potential usefulness of chotosan (CTS) and yokukansan (YKS), traditional herbal formulations called Kampo medicines, in the treatment of cognitive disturbance and BPSD in dementia patients, although the indications targeted by CTS and YKS in Kampo medicine differ. The availability of CTS and YKS for treating dementia patients is supported by preclinical studies using animal models of dementia that include cognitive/emotional deficits caused by aging and diabetes, dementia risk factors. These studies have led not only to the concept of a neuronal basis for the CTS- and YKS-induced amelioration of cognitive function and emotional/psychiatric symptom-related behavior in animal models, but also to a proposal that ingredient(s) of Uncariae Uncis cum Ramulus, a medicinal herb included in CTS and YKS, may play an important role in the actions of these formulae in dementia patients. Further studies are needed to clarify the active ingredients of these formulae and their target endogenous molecules implicated in the anti-dementia drug-like actions.

Diabetes-induced central cholinergic neuronal loss and cognitive deficit are attenuated by tacrine and a Chinese herbal prescription, kangen-karyu: elucidation in type 2 diabetes db/db mice

We investigated the effect of kangen-karyu (KK), a Chinese herbal prescription, on cognitive deficits and central cholinergic systems of type 2 diabetic db/db mice. Seven-week-old db/db (Y-db/db) mice received daily administration of test drugs during an experimental period of 12 weeks. At 18 weeks of age (O-db/db), the animals underwent the water maze test. Compared with age-matched control strain mice (O-m/m), vehicle-treated O-db/db mice showed impaired learning and memory performance. KK (100 - 200 mg/kg per day) and the reference drug tacrine (THA: 2.5 mg/kg per day) ameliorated the performance of O-db/db mice without affecting their serum glucose level. O-db/db mice had lower levels of brain-derived neurotrophic factor (BDNF) mRNA and its protein in the brain than O-m/m mice. Expression levels of central cholinergic marker proteins in the hippocampus and the number of cholinergic cells in the medial septum and basal forebrain were also significantly lower in O-db/db than in O-m/m mice, whereas no significant differences in the expression levels of these factors and the cell number were found between Y-m/m and Y-db/db mice. KK and THA treatment significantly reversed the down-regulated levels of cholinergic markers, choline acetyltransferase-positive cell number, and BDNF expression in db/db mice. These findings suggest that KK as well as THA prevents diabetes-induced cognitive deficits by attenuating dysfunction of central cholinergic systems.

Chronic brain hypoperfusion causes early glial activation and neuronal death, and subsequent long-term memory impairment

Reduction of cerebral blood flow is an important risk factor for dementia states and other brain dysfunctions. In present study, the effects of permanent occlusion of common carotid arteries (2VO), a well established experimental model of brain ischemia, on memory function were investigated, as assessed by reference and working spatial memory protocols and the object recognition task; cell damage to the hippocampus, as measured through changes in immunoreactivity for GFAP and the neuronal marker NeuN was also studied. The working hypothesis is that metabolic impairment following hypoperfusion will affect neuron and glial function and result in functional damage. Adult male Wistar rats were submitted to the modified 2VO method, with the right common carotid artery being occluded first and the left one week later, and tested seven days, three and six months after the ischemic event. A significant cognitive deficit was found in both reference and working spatial memory, as well as in the object recognition task, three and six months after surgery. Neuronal death and reactive astrogliosis were already present at 7 days and continued for up to 3 months after the occlusion; interestingly, there was no significant reduction in hippocampal volume. Present data suggests that cognitive impairment caused by brain hypoperfusion is long - lasting and persists beyond the time point of recovery from glial activation and neuronal loss.

Chotosan (Diaoteng San)-induced improvement of cognitive deficits in senescence-accelerated mouse (SAMP8) involves the amelioration of angiogenic/neurotrophic factors and neuroplasticity systems in the brain

Background

Chotosan (CTS, Diaoteng San), a Kampo medicine (ie Chinese medicine) formula, is reportedly effective in the treatment of patients with cerebral ischemic insults. This study aims to evaluate the therapeutic potential of CTS in cognitive deficits and investigates the effects and molecular mechanism(s) of CTS on learning and memory deficits and emotional abnormality in an animal aging model, namely 20-week-old senescence-accelerated prone mice (SAMP8), with and without a transient ischemic insult (T2VO).

Methods

Age-matched senescence-resistant inbred strain mice (SAMR1) were used as control. SAMP8 received T2VO (T2VO-SAMP8) or sham operation (sham-SAMP8) at day 0. These SAMP8 groups were administered CTS (750 mg/kg, p.o.) or water daily for three weeks from day 3.

Results

Compared with the control group, both sham-SAMP8 and T2VO-SAMP8 groups exhibited cognitive deficits in the object discrimination and water maze tests and emotional abnormality in the elevated plus maze test. T2VO significantly exacerbated spatial cognitive deficits of SAMP8 elucidated by the water maze test. CTS administration ameliorated the cognitive deficits and emotional abnormality of sham- and T2VO-SAMP8 groups. Western blotting and immunohistochemical studies revealed a marked decrease in the levels of phosphorylated forms of neuroplasticity-related proteins, N-methyl-D-aspartate receptor 1 (NMDAR1), Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), cyclic AMP responsive element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in the frontal cortices of sham-SAMP8 and T2VO-SAMP8. Moreover, these animal groups showed significantly reduced levels of vasculogenesis/angiogenesis factors, vascular endothelial growth factor (VEGF), VEGF receptor type 2 (VEGFR2), platelet-derived growth factor-A (PDGF-A) and PDGF receptor α (PDGFRα). CTS treatment reversed the expression levels of these factors down-regulated in the brains of sham- and T2VO-SAMP8.

Conclusion

Recovery of impaired neuroplasticity system and VEGF/PDGF systems may play a role in the ameliorative effects of CTS on cognitive dysfunction caused by aging and ischemic insult.

Ameliorative effects of yokukansan on learning and memory deficits in olfactory bulbectomized mice

AIM OF THE STUDY

Yokukansan (YKS) is a Japanese traditional herbal medicine and has been used for the treatment of the behavioral and psychological symptoms of dementia (BPSD). The present study aimed to clarify the effects of YKS on learning and memory impairments, and its mechanisms of action in olfactory bulbectomized (OBX) mice, one of the animal models of Alzheimer's disease (AD).

MATERIALS AND METHODS

OBX or sham-operated ddY mice were treated with YKS or donepezil (DPZ), a reference drug, and their cognitive performances were tested by the modified Y-maze test, novel object recognition test, and fear conditioning test to elucidate the spatial working memory, non-spatial short-term memory, and long-term memory, respectively. After completing the behavioral experiments, the expression level of cholinergic marker proteins and the activity of acetylcholinesterase (AChE) in the brain were analyzed by western blotting and Ellman's method, respectively.

RESULTS

OBX caused spatial working memory and non-spatial working memory impairments that were reversed by YKS and also by DPZ; however, YKS failed to affect the long-term memory deficits. Amelioration of the spatial working memory by YKS was reversible by scopolamine, a muscarinic receptor antagonist. YKS treatment reversed OBX-induced down-regulation of choline acetyltransferase and muscarinic muscarinic M₁ receptor expression without affecting muscarinic M₃ receptor expression or AChE activity.

CONCLUSION

These results demonstrate that YKS improves short-term memory deficit caused by OBX and that the effect is at least partly mediated by muscarinic receptor stimulation and the normalization of central cholinergic systems. The present findings also suggest that YKS has a therapeutic effect not only on BPSD, but also on memory impairment of AD.

Ameliorative effect of traditional Japanese medicine yokukansan on age-related impairments of working memory and reversal learning in rats

Aging is thought to impair prefrontal cortical (PFC) structure-sensitive cognitive functions and flexibility, such as working memory and reversal learning. A traditional Japanese medicine, yokukansan (YKS), is frequently used to treat age-related neurodegenerative disorders such as Alzheimer's disease in Japan, but its pharmacological properties have not been elucidated. The present study was designed to examine whether YKS improves age-related cognitive deficits using aged rats. YKS was administered to 21-month-old rats for 3 months. The ability to learn initially a reward rule for a T-maze discrimination task (initial learning) was examined in young control (4-month-old), aged control (24-month-old) and YKS-treated aged (24-month-old) rats. Subsequently, working memory and reversal learning were examined in delayed alternation and reversal discrimination T-maze tasks, respectively. Locomotor activity was also measured in new environments. Although performance accuracy in the initial learning procedure did not differ among any experimental groups, accuracy in the delayed alternation task was significantly decreased in aged rats compared to young rats. Aged rats also showed significant decreases in accuracy in the reversal discrimination task. YKS treatment significantly ameliorated the age-related decreases in accuracy in the delayed alternation and reversal discrimination tasks. The ameliorative effects of YKS on impaired delayed alternation performance were reduced by intracranial infusions of a dopamine D1 receptor antagonist, SCH 23390, into the prelimbic cortical region of the PFC, and the YKS effects on impaired reversal learning were done by the infusions into the orbitofrontal cortex (OFC). Locomotor activity did not change in any experimental group. Thus, YKS ameliorated age-related impairments of working memory and reversal learning, which might be mediated by a dopaminergic mechanism in the PFC structure. These investigations provide information important for the treatment of brain dysfunctions in the elderly people.

The modified 2VO ischemia protocol causes cognitive impairment similar to that induced by the standard method, but with a better survival rate

Permanent bilateral occlusion of the common carotid arteries (2VO) in the rat has been established as a valid experimental model to investigate the effects of chronic cerebral hypoperfusion on cognitive function and neurodegenerative processes. Our aim was to compare the cognitive and morphological outcomes following the standard 2VO procedure, in which there is concomitant artery ligation, with those of a modified protocol, with a 1-week interval between artery occlusions to avoid an abrupt reduction of cerebral blood flow, as assessed by animal performance in the water maze and damage extension to the hippocampus and striatum. Male Wistar rats (N = 47) aged 3 months were subjected to chronic hypoperfusion by permanent bilateral ligation of the common carotid arteries using either the standard or the modified protocol, with the right carotid being the first to be occluded. Three months after the surgical procedure, rat performance in the water maze was assessed to investigate long-term effects on spatial learning and memory and their brains were processed in order to estimate hippocampal volume and striatal area. Both groups of hypoperfused rats showed deficits in reference (F(₈,₁₇₂) = 7.0951, P < 0.00001) and working spatial memory [2nd (F(₂,₄₄) = 7.6884, P < 0.001), 3rd (F(₂,₄₄) = 21.481, P < 0.00001) and 4th trials (F(₂,₄₄) = 28.620, P < 0.0001)]; however, no evidence of tissue atrophy was found in the brain structures studied. Despite similar behavioral and morphological outcomes, the rats submitted to the modified protocol showed a significant increase in survival rate, during the 3 months of the experiment (P < 0.02).

Ameliorative effects of yokukansan, a traditional Japanese medicine, on learning and non-cognitive disturbances in the Tg2576 mouse model of Alzheimer's disease

AIM OF THIS STUDY

Aim of the present study is to clarify the effects of yokukansan (TJ-54) on learning and non-cognitive disturbances in the Tg2576 mouse expressing the human form of the APP695SWE (APP-Tg mice), which is considered to be an animal model of Alzheimer's disease.

MATERIALS AND METHODS

Powdered diets containing 0.5 and 1.0% TJ-54 were given to the mice for 10 months (from 5 to 15 months old). The Morris water-maze test, elevated plus-maze test, and open-field test were performed for evaluation of learning and non-cognitive disturbances.

RESULTS

Treatment with 1.0% TJ-54 for 5 months shortened the time it took for APP-Tg positive (+) mice to reach the platform in the Morris water-maze test. In the elevated plus-maze test, treatment with 1.0% TJ-54 for 2 months significantly reduced the increased number of entries and the time spent in open arms observed in APP-Tg(+) mice. In an open-field test, treatment of 1.0% TJ-54 for 9 months significantly suppressed the increase in locomotion observed in APP-Tg(+) mice.

CONCLUSION

These results suggest the possibility that TJ-54 ameliorates learning deficits and non-cognitive defects including a decrease in the anxiety (or disinhibition) and an increase in locomotor activity (hyperactivity) observed in APP-Tg(+) mice.

Chotosan enhances macrophage colony-stimulating factor mRNA expression in the ischemic rat brain and C6Bu-1 glioma cells

Macrophage colony stimulating factor (M-CSF) is a cytokine which has been recently reported to have a neuroprotective effect on ischemic rat brain. In this study, we investigated the effect of chotosan, an oriental medicine, which has been clinically demonstrated to be effective for the treatment of vascular dementia, on M-CSF gene expression in rats with permanent occlusion of bilateral common carotid arteries (P2VO) in vivo and in a C6Bu-1 glioma cell line in vitro. The expression level of M-CSF mRNA in the cerebral cortices of P2VO rats was significantly higher than that in the cerebral cortices of sham-operated animals. Repeated treatment of P2VO rats with chotosan (75 mg/kg per day) for 4 d after P2VO significantly increased the expression level of M-CSF mRNA in the cortex but it had no effect on the expression of beta-actin, granulocyte colony stimulating factor (G-CSF), granulocyte/macrophage colony stimulating factor (GM-CSF) mRNAs. Moreover, the present in vitro studies revealed that chotosan treatment (10-100 mug/ml) of C6Bu-1 glioma cells dose-dependently enhanced M-CSF mRNA expression without affecting the expression of G-CSF, GM-CSF, and inducible nitric oxide synthase mRNAs. The effect of chotosan was reversed by Ro 31-8220 (1 muM), a selective protein kinase C (PKC) inhibitor, but not by H-89 (10 muM), a selective protein kinase A (PKA) inhibitor. These findings suggest that the upregulatory effect of chotosan on M-CSF mRNA expression involves PKC and may play an important role in the anti-vascular dementia action of this formula.

The seed extract of Cassia obtusifolia ameliorates learning and memory impairments induced by scopolamine or transient cerebral hypoperfusion in mice

In the present study, we assessed the effect of the ethanolic extract of the seeds of Cassia obtusifolia (COE) on the learning and memory impairments induced by scopolamine or transient bilateral common carotid artery occlusion (2VO). In a study of the cholinergic dysfunction induced by scopolamine, single COE (25, 50, or 100 mg/kg, p.o.) administration significantly attenuated scopolamine-induced cognitive impairments as determined by the passive avoidance and Y-maze tasks (P<0.05) and also reduced escape-latency on the Morris water maze task (P<0.05). In the 2VO study, COE (50 mg/kg, p.o.) significantly reversed 2VO-induced cognitive impairments in mice by the passive avoidance and the Y-maze tasks (P<0.05). Moreover, COE (50 mg/kg, p.o.) also reduced escape-latency and prolonged swimming time in the target quadrant during a probe trial of the Morris water maze task (P<0.05). In an in vitro study, COE was found to inhibit acetylcholinesterase activity in a dose-dependent manner (IC(50) value: 81.6 microg/ml). Furthermore, COE also inhibited acetylcholinesterase activity in an ex vivo study. These results suggest that COE attenuates memory impairment induced by scopolamine or 2VO and that these effects are mediated by enhancing the cholinergic nervous system via acetylcholinesterase inhibition.

Chotosan, a kampo formula, ameliorates chronic cerebral hypoperfusion-induced deficits in object recognition behaviors and central cholinergic systems in mice

We previously demonstrated that the Kampo formula chotosan (CTS) ameliorated spatial cognitive impairment via central cholinergic systems in a chronic cerebral hypoperfusion (P2VO) mouse model. In this study, the object discrimination tasks were used to determine if the ameliorative effects of CTS on P2VO-induced cognitive deficits are a characteristic pharmacological profile of this formula, with the aim of clarifying the mechanisms by which CTS enhances central cholinergic function in P2VO mice. The cholinesterase inhibitor tacrine (THA) and Kampo formula saikokeishito (SKT) were used as controls. P2VO impaired object discrimination performance in the object recognition, location, and context tests. Daily administration of CTS (750 mg/kg, p.o.) and THA (2.5 mg/kg, i.p.) improved the object discrimination deficits, whereas SKT (750 mg/kg, p.o.) did not. In ex vivo assays, tacrine but not CTS or SKT inhibited cortical cholinesterase activity. P2VO reduced the mRNA expression of m(3) and m(5) muscarinic receptors and choline acetyltransferase but not that of other muscarinic receptor subtypes in the cerebral cortex. Daily administration of CTS and THA but not SKT reversed these expression changes. These results suggest that CTS and THA improve P2VO-induced cognitive impairment by normalizing the deficit of central cholinergic systems and that the beneficial effect on P2VO-induced cognitive deficits is a distinctive pharmacological characteristic of CTS.