HU-211, a nonpsychotropic cannabinoid,improves neurological signs and reduces brain damage after severe forebrain ischemia in rats

The purpose of the present study was to examine the dose-response relationship and the therapeutic time window for the synthetic nonpsychotropic cannabinoid (HU-211) as a neuroprotective agent in transient, severe forebrain ischemia in the rat. Adult Sprague-Dawley rats were subjected to 20 min common carotid artery occlusion (CCAo) 24 h after coagulation of both vertebral arteries. Thirty minutes after the onset of CCAo, rats received an iv injection of HU-211 2, 4, or 8 mg/kg in HPCD (n=12, 18, and 11, respectively), or the appropriate vehicle (n=20). Neurological signs were scored daily for 3 d following ischemia. A significant improvement (p<0.01, Kruskal-Wallis nonparametric test, followed by Mann-Whitney U-test,p<0.05) of neurological deficits by the 4 mg/kg dose of HU-211, was observed 24, 48 and 72 h after insult. On the third day post-CCAo, the rat brain was taken for histopathological evaluation of the CA-1 sector of the hippocampus. Counts of viable neurons in the hippocampal CA1 field showed significantly more live cells in the HU-211 (4 mg/kg) treated animals (P<0.001, ANOVA followed by Duncan’s post-hoc test,p<0.05). The drug was equally effective when given 30 and 60 min after ischemia, but neuroprotection was no longer significant after 3 h. We suggest that HU-211 may be a potential treatment for postischemic brain damage in human beings.     

Cerebroprotective effect of stable nitroxide radicals in closed head injury in the rat

Nitroxide stable radicals are unreactive toward most diamagnetic molecules, but readily undergo one-electron redox reactions with paramagnetic species such as free radicals and transition metals, thus serving as cell permeable antioxidants. The involvement of reactive oxygen species in the pathophysiology of neurotrauma has been well established. The neuroprotective properties of three nitroxides: 2,2,6,6-tetramethylpiperidine-1-N-oxyl (TPO), the hydrophilic analog: TPL, and its reduced form: TPH, were tested in a rat model of closed head injury (CHI). CHI was induced in ether anesthetized rats by a weight drop device and recovery was followed for up to 24 h. The ‘clinical status’ was evaluated according to a ‘Neurological Severity Score’ (NSS), at 1 h and 24 h, the difference between these scores, ΔNSS, reflecting the extent of recovery. Edema was assessed by measurement of water content at 24 h. The integrity of the blood-brain barrier (BBB) was investigated using Evans Blue extravasation. TPL, TPH and TPO facilitated clinical recovery, the latter causing a more pronounced effect (ΔNSS = 7.63 ± 0.26 in treated rats vs 4.94 ± 0.48 in control rats, P < 0.001). TPL was found to significantly reduce edema formation (80.13% ± 0.26 vs 83.65% ± 0.49, P < 0.001) and to ameliorate BBB disruption (P < 0.001). The therapeutic window of TPL was found to be in the range of 4 h after CHI. The mechanisms underlying the nitroxide neuroprotective activity presumably involve: (a) reoxidation of reduced transition metal ions; (b) a selective radical-radical reaction; and (c) catalytic removal of intracellular and extracellular O₂⁻. The results indicate that nitroxides could be used in neuroprotective treatment of CHI.     

Neuroprotective activity of HU-211, a novel NMDA antagonist,in global ischemia in gerbils

HU-211, a nonpsychotropic cannabinoid and a noncompetitive NMDA antagonist, was tested in a global ischemia model in the Mongolian gerbil. Male Mongolian gerbils underwent a 10-min bilateral common carotid artery occlusion. HU-211, administered iv at 4 mg/kg, 30 min postischemia, induced statistically significant neuroprotection of the CA1 subfield of the hippocampus. A dose-response study demonstrated an inverted U curve in which the 4mg/kg dose induced the best neuroprotection in the CA1 subfield of the hippocampus (p<0.05 ANOVA followed by Duncan's post-hoc test). The therapeutic window was then investigated, and in another study, HU-211 4 mg/kg were administered iv at 30, 60, 120, and 180 min postinsult. A statistically significant neuroprotection was detected at 30 and 60 min administration postinsult.     

Blockade ofCa influx through theN-methyl-d-aspartate receptor ion channel by the non-psychoactive cannabinoid HU-211

The effects of the synthetic non-psychoactive cannabinoid(+)-(3S,4S)-7-hydroxy-Δ⁶-tetrahydrocannabinol 1,1-dimethylheptyl (HU-211) on the activity of theN-methyl-d-aspartate (NMDA) receptor/ion channel were examined. HU-211 non-competitively blocks the increase in binding of[³H]N-[1-(2-thienyl)-cyclohexyl]piperidine ([³H]TCP) induced by the polyamines spermine and spermidine or by glutamate and glycine. HU-211 does not, however, affect the direct binding of [³H]glycine and [³H]glutamate to their binding sites on the NMDA receptor, which suggests that the effects of HU-211 are not mediated via the binding sites of glutamate-, glycine- and phencyclidine-like drugs or of polyamines. HU-211 can also block⁴⁵Ca²⁺ uptake through the NMDA-receptor/ion channel in primary cell cultures of rat forebrain. All of the above inhibitory effects of HU-211 on the NMDA-receptor/ion channel activity are stereospecific, since the(−)(3R,4R) enantiomer (HU-210) is ineffective.     

Development of HU-211 as a neuroprotectant for ischemic brain damage

Abstract

HU-211 (Dexanabinol), a putative neuroprotective agent, was evaluated in a number of animal models including closed head injury, optic nerve crush, global ischemia and focal ischemia. In these modelsa single injection of HU-211 given after the insult confers long term functional improvement and significant increase in neuronal survival. Neuroprotective doses of HU-211 were found to be safe in a 14 day toxicological study in two species. In terms of mechanism, the compound behaves as a noncompetitive NMDA antagonist in vitro and in vivo. It blocks NMDA stimulated calcium influx in primary neuronal culture, and head injury related calcium influx in rats. In addition, HU-211 is a potent scavenger of peroxy and hydroxy radicals in vitro and it protects cultured neurons from toxicity of radical generators. Thus, Dexanabinol holds a unique position among putative neuroprotective agents since it combines NMDA blocking activity and free radical scavenging properties in one molecule. These observations support the development of HU-211 as a novel' multiple-action treatment approach for brain damage associated with stroke, cardiac arrest and trauma. [Neurol Res 1995; 17: 275-280]     

神经生长因子对兔局灶性脑缺血再灌注损伤的治疗时间窗及MR影像学评价

目的研究神经生长因子(NGF)对脑缺血再灌注损伤保护作用的有效时间窗,同时利用MR成像技术对其进行评价。方法采用兔大脑中动脉阻断(MCAO)局灶性脑缺血2 h再灌注72 h模型,分别于缺血再灌注0、1、36、h应用微量进样器将NGF立体定向导入梗死灶周,并于再灌注不同时间点应用MR影像学、TTC染色和流式细胞术评价家兔梗死体积、神经功能缺损和凋亡状态。结果缺血再灌注0、13、h组梗死灶周注射NGF后,经MRI检查所测梗死体积分别为(229.9±17.1)(、260.7±24.2)、(314.6±25.3)mm3,与对照组[(468.6±29.7)mm3]比较差异有统计学意义(均P<0.01);缺血再灌注6 h组梗死体积为(441.1±14.8)mm3,与对照组比较差异无统计学意义(P>0.05)。采用TTC染色所测梗死体积与MRI检查结果一致。脑缺血再灌注3 h内注射NGF,其神经功能缺损评分明显降低,凋亡率明显下降;再灌注6 h后注射NGF则无明显作用。结论NGF对兔局灶性脑缺血再灌注损伤的有效时间窗为再灌注损伤3 h内,MR影像学检查可作为定量评价基因疗效的可靠指标。     

Therapeutic time window for the neuroprotective effects of NGF when administered after focal cerebral ischemia

In the present study, we evaluated the neuroprotection time window for nerve growth factor (NGF) after ischemia/reperfusion brain injury in rabbits as related to this anti-apoptosis mechanism. Male New Zealand rabbits were subjected to 2 h of middle cerebral artery occlusion (MCAO), followed by 70 h of reperfusion. NGF was administered after injury to evaluate the time window. Neurological deficits, infarct volume, neural cell apoptosis and expressions of caspase-3 and Bcl-2 were measured. Compared to saline-treated control, NGF treatment at 2, 3 and 5 h after MCAO significantly reduced infarct volume, neural cell apoptosis and expression of caspase-3 (P < 0.01), up-regulated the expression of Bcl-2 and improved functional recovery (P < 0.01). However, treatment at latter time points did not produce significant neuroprotection. Neuroprotection treatment with NGF provides an extended time window of up to 5 h after ischemia/reperfusion brain injury, in part by attenuating the apoptosis.     

Neurological soft signs (NSS) in 200 treatment-naïve cases with schizophrenia: a community-based study in a rural setting

Several studies have reported neurological soft signs (NSS) to be common in individuals with schizophrenia. The majority of these studies are based on clinical samples exposed to neuroleptic treatment. The present study reports on 200 treatment-na?ve and community-identified cases of schizophrenia and 78 healthy individuals from the same area, evaluated using the Neurological Evaluation Scale (NES). The median NES score was 5.0 for cases of schizophrenia and 1.5 for healthy subjects. The impairment rate of NSS in cases with schizophrenia was 65.0% against 50.0% in healthy subjects, and the difference was statistically significant (chi2 = 5.30; df = 1; P < 0.021). NSS abnormality is as common in treatment-na?ve cases as reported in many studies in those on neuroleptic medication. There was no significant relation between the NSS impairment and duration of illness, remission status, positive symptoms, negative symptoms and disorganized symptoms.     

Mild postischemic hypothermia limits cerebral injury following transient focal ischemia in rat neocortex

Intraischemic mild hypothermia has been shown to attenuate cerebral infarction occurring after transient focal ischemia. In contrast, the capacity of mild hypothermia to provide a protective effect when administered postischemically has not been clearly defined for transient focal events such as occur in many types of stroke. The present study addressed this issue by investigating the influence of timing and duration of mild hypothermia on cerebral infarction in a rat model of reversible focal ischemia. Sprague-Dawley rats (n = 45) were subjected to 3 h of focal neocortical ischemia by occluding reversibly one middle cerebral artery and both carotid arteries. Mild hypothermia was established after reperfusion and maintained for brief (1 h) or prolonged (21 h) periods. Animals were sacrificed 24 or 48 h after ischemia. A significant reduction (32%) in the volume of infarction was obtained when hypothermia was established immediately after reperfusion and maintained for a prolonged (21 h) period. In contrast, immediate but brief (1 h) hypothermia did not reduce infarction volume. Delaying hypothermia until 30 min post reperfusion and maintaining it for 21 h reduced infarction volume by 22%; however, this effect did not achieve statistical significance. These findings demonstrate that mild postischemic hypothermia is capable of protecting against cerebral injury following transient focal ischemia but that prolonged hypothermia is required to achieve this effect. These findings are consistent with increasing evidence that the window of therapeutic opportunity after transient focal ischemia is rather brief and that critical mechanisms involved in this form of ischemic injury remain activated over a rather lengthy postischemic interval.     

急进高原轻-中度闭合性颅脑损伤后在不同海拔下伤情变化的观察

目的观察急进高原地区轻-中度闭合性颅脑损伤(mmCHI)急性期转运至不同海拔高度下的伤情变化。 方法平原饲养的健康雄性SD大鼠称基础体质量,模拟海拔6.0 km持续低压、低氧处理24 h后再次称质量,采用气动式撞击装置制作mmCHI模型,观察大鼠致伤后生命体征变化并进行神经功能缺损评分（NSS）,随机分为不同海拔高度组（6.0、4.5、3.0 km）进行观察,并分别对相应海拔高度下大鼠在mmCHI后6、12、24 h的NSS评分、体质量、脑含水量、脑含水量与体质量的比值及颅脑MRI检查。 结果急进高原mmCHI大鼠在致伤后6 h各海拔高度组NSS评分减少值明显低于伤后12、24 h评分减少值（P<0.05）;伤后快速下降至3.0 km组大鼠体质量下降最少,与伤后滞留于6.0 km及下降至4.5 km组比较,差异具有显著统计学意义（P<0.05）;伤后脑含水量各组比较差异无统计学意义;伤后下降至4.5 km大鼠的脑含水量占体质量的百分比最低,与其他2组比较差异具有显著统计学意义（P<0.05）;动态MRI定量检测分析结果显示伤后下降至4.5 km大鼠的胼胝体水肿及脑室扩张程度明显低于其他海拔高度（P<0.05）。 结论极高海拔环境下mmCHI后早期、阶梯式转运至低海拔地区可减轻继发性颅脑损伤。高原颅脑损伤后早期MRI检查可对预后判断及临床诊治有指导意义。     

Sustained attention following mild closed-head injury

Abstract

The sustained-attention performance of patients with mild closed-head injury (CHI) was examined within one month of injury using a high-event rate, digit-discrimination vigilance task with two levels of stimulus degradation (undegraded, highly degraded). Under undegraded stimulus conditions, vigilance performance for mild CHI subjects, uninjured case-matched control subjects, and college students was highly accurate and remained so across the entire task period. When stimuli were presented in degraded fashion, however, all three groups showed a similar decline over time (i.e., vigilance decrement) in hit rates and d' scores. Although mild CHI did not lead to a greater rate of deterioration in vigilance performance in the degraded stimulus condition, it did produce lower overall levels of sensitivity (d') in target detection. These results suggest that, during the first month after mild CHI, vigilance performance is unimpaired under normal task conditions, but may fall short under task conditions that require sustained effortful processing. These findings join a growing body of evidence showing that mild CHI can lead to measurable deficits in cognitive functioning.     

Dl-3-n-butylphthalide promotes synaptic plasticity by activating the Akt/ERK signaling pathway and reduces the blood–brain barrier leakage by inhibiting the HIF-1α/MMP signaling pathway in vascular dementia model mice

Aims

DL-3-n-butylphthalide (NBP) exerts beneficial effects on global cognitive functions, but the underlying molecular mechanisms are still poorly understood. The present study aimed to investigate whether NBP mediates synaptic plasticity and blood–brain barrier (BBB) function, which play a pivotal role in the pathogenesis of vascular dementia (VaD), in a mouse model of bilateral common carotid artery stenosis (BCAS).

Methods

NBP was administered to model mice at a dose of 80 mg/kg by gavage for 28 days after surgery. Cognitive function was evaluated by behavioral tests, and hippocampal synaptic plasticity was evaluated by in vivo electrophysiological recording. Cerebral blood flow (CBF), hippocampal volume, and white matter integrity were measured with laser speckle imaging (LSI) and MRI. In addition, BBB leakage and the expression of proteins related to the Akt/ERK and HIF-1α/MMP signaling pathways were assessed by biochemical assays.

Results

NBP treatment alleviated cognitive impairment, hippocampal atrophy, and synaptic plasticity impairment induced by BCAS. In addition, NBP treatment increased CBF, promoted white matter integrity, and decreased BBB leakage. Regarding the molecular mechanisms, in mice  with BCAS, NBP may activate the Akt/ERK signaling pathway, which upregulates the expression of synapse-associated proteins, and it may also inhibit the HIF-1α/MMP signaling pathway, thereby increasing the expression of tight junction (TJ) proteins.

Conclusion

In conclusion, our results demonstrated the therapeutic effects of NBP in improving cognitive function via a wide range of targets in mice subjected to BCAS.     

Is mild vascular cognitive impairment reversible? Evidence from a study on the effect of carotid endarterectomy

Abstract

Mild vascular cognitive impairment (mVCI) is a broader term that is intended to detect cognitive loss before the development of dementia. The identification of preventable risk factors as well as therapeutic strategies of intervention is still unclear. It has been suggested that carotid endarterectomy (CEA) improves cognitive functions, beyond the well-known preventive effect upon future stroke events. In the present study, we evaluated the beneficial effect of CEA in restoring mVCI. Among a large sample of subjects, who underwent CEA for severe carotid stenosis, two groups were identified according to the absence (CON) or the presence of cognitive impairment (mVCI). A multidimensional neuropsychological and behavioural assessment was performed in the week prior, and at a 3-month follow-up after CEA. The incidence of mVCI in this sample was 38%. Seventy-eight patients completed the follow-up (48 CON, 30 mVCI). Both groups showed a clinical improvement after CEA, although the effect was significantly higher in the mVCI group in regard to verbal memory (short story, p < 0.05), and attention (digit span, p < 0.05) scores. At follow-up, 60% of mVCI subjects were classified as having normal cognitive functions. Index of disease severity and peripheral arterial disease were found to be the predictors of improvement. These findings support that mVCI represents a heterogeneous, in some cases reversible condition. CEA might be considered a therapeutic option to treat and prevent cognitive decline in mVCI patients.     

Augmentation of the development of behavioral tolerance to cannabinoid administration through pavlovian conditioning

This investigation examined the effects, in female rats, of a Pavlovian conditioning paradigm on the development of tolerance to hypolocomotion induced by the cannabinoid agonist HU-210. Rats were administered HU-210 and placebo in either an associative or a nonassociative fashion. The results indicated that rats in the associative paradigm developed tolerance significantly faster than those in the nonassociative group (p < 0.03). Subsequently, once tolerance had developed, the associative group of rats was administered HU-210 and placebo in the opposite environments. There were no differences found in locomotion between the CS+ and CS- environments following administration of HU-210. However, when the placebo was administered in the CS+ environment, there was a trend towards increased activity levels (p = 0.06), suggesting withdrawal-like behavior. These findings indicate that the underlying physiological mechanisms of tolerance development in the cannabinoid system are hastened by conditioning, but that these physiological alterations are not contingent upon the associative parameters used for drug administration.     

Neuroprotective effect of immunosuppressant FK506 in transient focal ischemia in rats: Therapeutic time window for FK506 in transient focal ischemia

Abstract

Tacrolimus (FK506), an immunosuppressant currently used in clinic, is known to have neuroprotective properties. However, effects in focal ischemia are shown only in a endothelin induced middle cerebral artery (MCA) occlusion model or with filament technique at a relatively high dose. We have previously shown that FK506 had significant protective effects at a low dose of 0.3mg kg^-1 when administered immediately after ischemia. In this study, we explored the therapeutic time window of FK506 at this low dose, in a transient focal ischemia model using filament technique. Male Sprague-Dawley rats were subjected to 2 h MCA occlusion and subsequent reperfusion. They received FK506 or vehicle (0.3 mg kg^-1) i.v. at 30, 60 or 120 min after induction of ischemia, and were decapitated 24 h after ischemia. FK506 injected at 30 and 60 min significantly reduced cortical infarction volume (FK506 vs. vehicle; 30 min: 95 ± 33 mm³ vs. 170 ± 62 mm³, p < 0.05; 60 min: 93 ± 45 mm³, vs. 168 ± 35 mm³, p < 0.05, respectively). FK506 was ineffective when given at 120 min after ischemia. FK506 had no effect on edema formation, nor on the infarct volume in striatum. The therapeutic time window for this low dose of FK506 given i.v. is between 60 and 120 min in this model. [Neurol Res 2001; 23: 755-760]     

Extended therapeutic window and functional recovery after intraarterial administration of neuregulin-1 after focal ischemic stroke.

We have previously shown that neuregulin-1 (NRG-1) protects neurons from ischemic brain injury if administered before focal stroke. Here, we examined the therapeutic window and functional recovery after NRG-1 treatment in rats subjected to 90 mins of middle cerebral artery occlusion (MCAO) and 24 h of reperfusion. Neuregulin-1 (2.5 ng/kg bolus, 1.25 ng/kg/min infusion) reduced infarct volume by 89.2%+/-41.9% (mean+/-s.d.; n=8; P<0.01) if administered immediately after the onset of reperfusion. Neuroprotection was also evident if NRG-1 was administered 4 h (66.4%+/-52.6%; n=7; P<0.01) and 12 h (57.0%+/-20.8%; n=8; P<0.01) after reperfusion. Neuregulin-1 administration also resulted in a significant improvement of functional neurologic outcome compared with vehicle-treated animals (32.1%+/-5.7%; n=9; P<0.01). The neuroprotective effect of the single administration of NRG-1 was seen as long as 2 weeks after treatment. Neurons labeled with the neurodegeneration marker dye Fluoro-JadeB were observed after MCAO in the cortex, but the numbers were significantly reduced after NRG-1 treatment. These results indicate that NRG-1 is a potent neuroprotective compound with an extended therapeutic window that has practical therapeutic potential in treating individuals after ischemic brain injury.     

Neurological soft signs (NSS) in 200 treatment-naïve cases with schizophrenia: a community-based study in a rural setting

Several studies have reported neurological soft signs (NSS) to be common in individuals with schizophrenia. The majority of these studies are based on clinical samples exposed to neuroleptic treatment. The present study reports on 200 treatment-naïve and community-identified cases of schizophrenia and 78 healthy individuals from the same area, evaluated using the Neurological Evaluation Scale (NES). The median NES score was 5.0 for cases of schizophrenia and 1.5 for healthy subjects. The impairment rate of NSS in cases with schizophrenia was 65.0% against 50.0% in healthy subjects, and the difference was statistically significant ( &#104 2 = 5.30; df = 1; P < 0.021). NSS abnormality is as common in treatment-naïve cases as reported in many studies in those on neuroleptic medication. There was no significant relation between the NSS impairment and duration of illness, remission status, positive symptoms, negative symptoms and disorganized symptoms.     

Screening,rubella vaccination,and childhood hearing impairment in Taiwan

Childhood hearing impairment (CHI) is a major developmental disability, but data at the national level are limited, especially those on the changes in the prevalence over time. In Taiwan, the government began to certify disabled residents for providing various services in 1980 and maintains a registry of certified cases, which provides a rare opportunity for studying the trends of CHI prevalence. Using the registry data, we estimated the prevalence of CHI by age and severity and explored factors affecting its changes over time. From 2000 to 2011, the registered cases under 17 years old ranged from 3427 to 4075. The overall prevalence increased from 2000 to 2006, but then decreased till 2011. While the prevalence of mild CHI increased over the years, such a pattern was not observed in moderate or severe CHI. In general, the overall prevalence increased over the years in the age groups <3 years, 3–5 years, and 6–11 years (p < 0.01), and the largest increase was observed in the age group <3 years, particularly after the promotion of screening by the government in 2003. The decrease after 2006 was mainly attributable to decreases in the age groups 12–14 (with a decreasing trend from 2001, p < 0.01) and 15–17 years (with a decreasing trend from 2004, p < 0.01). The timing was related to the implementation of a nationwide rubella vaccination program. Similar decreases had been observed in countries with rubella vaccination programs.     

The synthetic cannabinoid HU-210 attenuates neural damage in diabetic mice and hyperglycemic pheochromocytoma PC12 cells

Diabetic neuropathy (DN) is a common complication of diabetes mellitus resulting in cognitive dysfunction and synaptic plasticity impairment. Hyperglycemia plays a critical role in the development and progression of DN, through a number of mechanisms including increased oxidative stress. Cannabinoids are a diverse family of compounds which can act as antioxidative agents and exhibit neuroprotective properties. We investigated the effect of the synthetic cannabinoid HU-210 on brain function of streptozotocin (STZ)-induced diabetic mice. These animals exhibit hyperglycemia, increased cerebral oxidative stress and impaired brain function. HU-210, through a receptor independent pathway, alleviates the oxidative damage and cognitive impairment without affecting glycemic control. To study the neuroprotective mechanism(s) involved, we cultured PC12 cells under hyperglycemic conditions. Hyperglycemia enhanced oxidative stress and cellular injuries were all counteracted by HU-210-in a dose dependent manner. These results suggest cannabinoids might have a therapeutic role in the management of the neurological complications of diabetes.     

神经生长因子的脑保护作用与Caspase-3表达的相关性

目的 研究神经生长因子(NGF)的脑保护时间窗与半胱天冬酶-3(Caspase-3)表达的相关性.方法 采用兔局灶性脑缺血再灌注损伤模型,分别于再灌注后0h、1h、3h和6h将NGF立体定向导入梗死灶周,再灌注72h观察神经功能、梗死体积、灶周凋亡率和Caspase-3表达.结果 再灌注0h、1h和3 h灶周给予NGF,梗死体积分别较对照组下降50.1%、42.5%和35.2%,相应的灶周凋亡率及Caspase-3表达明显下降,神经功能恢复较好,用药越早越明显;再灌注6h给药,则无明显作用.相关分析显示梗死体积变化与Caspase-3表达具有明显相关性(P＜0.05).结论 NGF脑保护治疗时间窗与Caspase-3表达相关,抑制Caspase-3表达可能是NGF介导神经保护作用的机制之一.