经鼻滴入海人藻酸引起C57BL/6小鼠嗅球和海马区神经元的退行性病变

目的 应用海人藻酸(KA)在C57BL／6小鼠建立神经退行性病变动物模型并观察其对嗅球神经元的影响。方法 经鼻滴人KA应用尼氏和嗜银染色观察海马及嗅球的病理变化，免疫组化检测Cyclooxygenase2(COX-2)的表达。结果 经鼻滴入KA成功地在C57BL／6小鼠建立了神经退行性病变动物模型，KA通过嗅神经引起双侧嗅球和海马损伤，其病变程度与小鼠体重和滴入KA剂量有关，同时KA引起了脑内明显的胶质细胞增生和炎症因子COX-2在嗅球部的表达。结论 经鼻滴入KA能够引起嗅球和海马的损伤。     

Systemic overexpression of the alpha 1B-adrenergic receptor in mice: an animal model of epilepsy

PURPOSE: A lack of selective alpha1-adrenergic receptor (alpha1-ARs) agonists and antagonists has made it difficult to clarify the precise function of these receptors in the CNS. We recently generated transgenic mice that overexpress either wild-type or a constitutively active mutant alpha 1B-AR in tissues that normally express the receptor. Both wild-type and mutant mice showed an age-progressive neurodegeneration with locomotor impairment and probable stress-induced motor events, which can be partially reversed by alpha 1-AR antagonists. We hypothesized that the wild-type and mutant mice may exhibit spontaneous epileptogenicity as compared with normal (nontransgenic) mice. METHODS: Normal, wild-type, and mutant mice were studied. Twenty mice (1 year old) underwent prolonged video-EEG monitoring over a 4-week period. Raw EEG data were blindly analyzed by visual inspection for the presence of interictal and ictal epileptic activities. RESULTS: During the acute postoperative period (< or = 3 days), both wild-type (26.1 +/- 8.07 spikes/day) and mutant mice (116.87 +/- 55.13) exhibited more frequent interictal spikes than did normal mice (2.17 +/- 0.75; p value, <0.05), but all three groups showed EEG and clinical seizures. During the later monitoring periods (>3 days), wild-type and mutant mice showed more frequent interictal spikes (15.44 +/- 4.07; p < 0.01; and 6.05 +/- 2.46; p < 0.05, respectively) as compared with normal mice (0.41 +/- 0.41), but only mutant mice had spontaneous clinical seizures (means +/- SEM). CONCLUSIONS: The selective overexpression of the alpha 1B-AR is associated with increased in vivo spontaneous interictal epileptogenicity and EEG/behavioral seizures. These results suggest a possible role (direct or indirect) for the alpha 1B-ARs in the development and expression of epileptogenicity.     

Dysregulation of dopamine signaling in the dorsal striatum inhibits feeding

Dopamine signaling is an important component of many goal-directed behaviors, such as feeding. Acute disruption of dopamine signaling using pharmacological agents tends to inhibit normal feeding behaviors in rodents. Likewise, genetically engineered dopamine-deficient (DD) mice are unable to initiate sufficient feeding and will starve by approximately 3 weeks of age if untreated. Adequate feeding by DD mice can be achieved by daily administration of L-3,4-dihydroxyphenylalanine (L-dopa), a precursor of dopamine, which can be taken up by dopaminergic neurons, converted to dopamine, and released in a regulated manner. In contrast, adequate feeding cannot be restored with apomorphine (APO), a mixed agonist that activates D1 and D2 receptors. Viral restoration of dopamine production in neurons that project to the dorsal striatum also restores feeding in DD mice. Administration of amphetamine (AMPH) or nomifensine (NOM), drugs which increase synaptic dopamine concentration, inhibits food intake in virally rescued DD mice (vrDD) as in control animals. These results indicate that the dysregulation of dopamine signaling in the dorsal striatum is sufficient to induce hypophagia and suggest that regulated release of dopamine in that brain region is essential for normal feeding and, probably, many other goal-directed behaviors.     

Redefining the Koizumi model of mouse cerebral ischemia: A comparative longitudinal study of cerebral and retinal ischemia in the Koizumi and Longa middle cerebral artery occlusion models

Cerebral and retinal ischemia share similar pathogenesis and epidemiology, each carrying both acute and prolonged risk of the other and often co-occurring. The most used preclinical stroke models, the Koizumi and Longa middle cerebral artery occlusion (MCAO) methods, have reported retinal damage with great variability, leaving the disruption of retinal blood supply via MCAO poorly investigated, even providing conflicting assumptions on the origin of the ophthalmic artery in rodents. The aim of our study was to use longitudinal in vivo magnetic resonance assessment of cerebral and retinal vascular perfusion after the ischemic injury to clarify whether and how the Koizumi and Longa methods induce retinal ischemia and how they differ in terms of cerebral and retinal lesion evolution. We provided anatomical evidence of the origin of the ophthalmic artery in mice from the pterygopalatine artery. Following the Koizumi surgery, retinal responses to ischemia overlapped with those in the brain, resulting in permanent damage. In contrast, the Longa method produced only extensive cerebral lesions, with greater tissue loss than in the Koizumi method. Additionally, our data suggests the Koizumi method should be redefined as a model of ischemia with chronic hypoperfusion rather than of ischemia and reperfusion.     

High frequency stimulation of the subthalamic nucleus impacts adult neurogenesis in a rat model of Parkinson's disease

APP.V717I and Tau.P301L transgenic mice develop Alzheimer's disease pathology comprising important aspects of human disease including increased levels of amyloid peptides, cognitive and motor impairment, amyloid plaques and neurofibrillary tangles. The combined model, APP.V717I × Tau.P301L bigenic mice (biAT mice) exhibit aggravated amyloid and tau pathology with severe cognitive and behavioral defects. In the present study, we investigated early changes in synaptic function in the CA1 and CA3 regions of acute hippocampal slices of young APP.V717I, Tau.P301L and biAT transgenic animals. We have used planar multi-electrode arrays (MEA) and improved methods for simultaneous multi-site recordings from two hippocampal sub-regions. In the CA1 region, long-term potentiation (LTP) was severely impaired in all transgenic animals when compared with age-matched wild-type controls, while basal synaptic transmission and paired-pulse facilitation were minimally affected. In the CA3 region, LTP was normal in Tau.P301L and APP.V717I but clearly impaired in biAT mice. Surprisingly, frequency facilitation in CA3 was significantly enhanced in Tau.P301L mice, while not affected in APP.V717I mice and depressed in biAT mice. The findings demonstrate important synaptic changes that differ considerably in the hippocampal sub-regions already at young age, well before the typical amyloid or tau pathology is evident.     

Immunohistochemical study on the distribution of Bcl-2 and Bax in the central nervous system of the transgenic mice expressing a human Cu/Zn SOD mutation

In the present study, we performed immunohistochemical studies to investigate the changes of Bcl-2 and Bax in the central nervous system of the transgenic mice expressing a human Cu/Zn SOD mutation. In contrast to the controls, a high density of Bcl-2-IR astrocytes were detected all around the gray matter of the spinal cord of the mutant transgenic mice. Bcl-2-IR astrocytes were also detected in the cerebellum and brainstem of transgenic mice. Specific immunoreactivity for Bax was seen in the spinal cord and brainstem of transgenic mice. Immunostaining for Bax was identified only in neurons and not in glial cells. Our present study demonstrated the distribution of Bcl-2 and Bax in detail using immunohistochemical methods through the central nervous system of the transgenic mice, for the first time.     

Highly active antiretroviral therapy of cognitive dysfunction and neuronal abnormalities in SCID mice with HIV encephalitis

Our objective was to determine if highly active antiretroviral therapy (HAART), previously shown to ameliorate several pathological features of HIV encephalitis (HIVE) in a SCID mouse model, would also reduce additional established pathological features of HIV: cognitive dysfunction, TNF-α, production, and reduced MAP-2 expression. SCID mice with HIVE and control mice inoculated with uninfected monocytes were administered HAART or saline. The HIV pathological features evaluated included astrogliosis, viral load, neuronal apoptosis, MAP-2 expression, mouse TNF-α mRNA production and learning acquisition and retention. HAART reduced the HIV-induced viral load, and the astro- and microgliosis as previously observed; this effect was extended to HIV-induced increases in TNF-α mRNA production. In contrast, although HIV produced the cognitive deficits previously observed and also decreased MAP-2 expression in the area surrounding the injected HIV-infected human monocytes, HAART did not attenuate these effects. Interestingly, there was no neuronal apoptosis evident at the time point reflecting the above pathology. The results of this study combined with previous reports indicate that HAART reduces TNF-α mRNA, viral load and astrogliosis; however, HAART does not improve HIV-induced cognitive dysfunction or MAP-2 decreases. These results suggest that viral load, astrogliosis, TNF- α and apoptosis are not prominent in the pathogenesis of early functional deficits related to decreased MAP-2 expression or cognitive dysfunction in HIVE in SCID mice.     

The Hyperglycaemic Activity of Some Catecholamines and the Effect of α- and β-Adrenergic Blocking Compounds in the Mouse

In order to classify the receptors involved in the hyperglycaemic response to catecholamines in the mouse, the relative potency of noradrenaline, adrenaline and isoprenaline in the induction of hyperglycaemia has been tested by giving increasing doses from 10 μg/kg to 1 mg/kg of one of the amines intraperitoneally. Following catecholamine administration the maximal concentration of glucose in the blood occurred between 10 and 30 min. and amounted to about 300 mg%. The relative potency was: adrenaline > noradrenaline while isoprenaline was inactive. The antagonistic effect on adrenaline induced hyperglycaemia of the α-adrenergic blocking compounds: phenoxybenzamine HCl (dibenzyline®) and phentolamine (regitin®) and the β-adrenergic blocking compounds: 1-(isopropylamino)-3-(o-phenoxyphenoxy)-2-propanol (Ph QA 33) and propranolol were tested by giving 1 and 10 mg/kg intraperitoneally 30 min. before the administration of adrenaline. Only phentolamine at the highest dose level was capable of preventing the hyperglycaemic response to adrenaline. Phenoxybenzamine, Ph QA 33 and propranolol proved to be inactive. It is concluded that the mechanism of adrenaline induced hyperglycaemia in mice cannot be explained simply by an α- and/or β-receptor activation.     

Icariin decreases neuro-pathogenesis and improves learning and memory functions in Tg2576 mice

Alzheimer′s disease(AD) is one of the most common neurodegenerative diseases,showing progressive memory and cognitive deficits.The predominant neuropathological features of AD are extracellular senile plaques(SP) composed by over expression of amyloid beta protein(Aβ),hyperphosphorylation of Tau protein forming the neurofibrillary tangles(NFTs) and neuronal loss in the specific brain subregions.However,the cause of dementia of AD are still not known,the neurotoxicity of over expressed Aβ coming from the proteolysis of amyloid precursor protein(APP) may play a important role.Aβ neurotoxicity has been widely reported in vitro and in vivo,including the impairment of long term potentiation(LTP),disruption of synaptic plasticity.Aβ also triggered neuron inflammation,and disturbed neurogenesis.caused neuronal oxidative damage and apoptosis,eventually resulted in memory loss At this moment,there are no effective pharmacologic interventions that could halt the progression of AD.Current pharmacotherapies,such as acetylcholinesterase inhibitors including donepezil,rivastigmine and galantamine,and a NMDA antagonist,memantine,improve symptoms but do not block the disease progression.New strategies to slow and/or reverse the pathogenesis of patients with AD are greatly needed.Traditional Chinese Medicine such as icariin may provide an unique opportunity for seeking more safe and effective therapies for AD.In this study we were examine the protective effect of icariin on Tg2576 mice,a well established animal model of AD.Our results demonstrated that chronic treatment of Tg2576 mice with icariin from age of 8 to 11 months,could improve the memory function of Tg2576 mice.In addition,icariin decreased the APP,Aβ levels,and amyloid plaque number in Tg2576 mouse brain.Finally,icariin promoted cell proliferation and differentiation into neuron in the dentate gyrus(DG) of hippocampus in aged Tg2576 mouse.Neurogenesis following icariin administration may due to the decrease of Aβ levels and phosphodiesterase type 5(PDE5),amelioration of the Aβ neurotoxicity,and increase of brain-derived neurotrophic factor(BDNF) expression in mouse brain.In summary,aged Tg2576 mice deministrated neuropathogenesis and cognitive deficits in thebrain,.Chronic treatment of icariin in Tg2576 mice significantly decreased the neuropathogenesis and improved cognitive function.Icariin stimulates neurogenesis in aged Tg2576 mice displayed further neuro-protection in aged brain.Our results provide solid evidence in support that icariin could be a potential compound for AD therapy.     

SRC-1基因在小鼠神经干细胞分化过程中的变化

目的观察类固醇受体辅助活化因子-1(SRC-1)基因在小鼠神经干细胞(NSCs)体外培养分化过程中表达的变化。方法用机械分离和酶消化法从1~3 d小鼠大脑皮质获取NSCs原代细胞,体外培养获神经球,传代并消化,经血清诱导神经球细胞分化。形态学、细胞免疫荧光实验观察神经球形态、Nestin表达鉴定NSCs;抗体分别标记神经元、星形胶质细胞,检测细胞分化d 3、9的细胞类型。RT-qPCR和免疫印迹法检测细胞分化d 0、3、9 SRC-1基因mRNA和蛋白的表达。结果新生小鼠大脑皮质获取的细胞,体外培养能扩增形成神经球,Nestin阳性表达。NSCs分化d 3主要为神经元,d 9主要为星形胶质细胞。与NSCs分化d 0相比,SRC-1表达在分化d 3明显升高,在分化d 9明显降低。 结论 成功分离并获取新生小鼠皮质NSCs。在NSCs分化中,SRC-1表达量有明显变化,分布依次为神经元>NSCs>星形胶质细胞。