冻干甲型肝炎-腮腺炎联合疫苗猴体安全性及免疫原性研究试验

为了观察冻干甲型肝炎-腮腺炎联合疫苗免疫恒河猴后的安全性及免疫原性,用静脉注射和丘脑注射的方式接种疫苗,观察恒河猴的临床症状、体征、生化、免疫学反应以及脑和肝组织的病理变化。结果未见临床症状和体征的异常改变,ALT正常,抗-HAV、抗流行性腮腺炎病毒的抗体在观察期内持续阳性,脑组织和肝组织无病毒性肝炎和腮腺炎病毒引起的病理性改变。因此该冻干甲型肝炎堋;腺炎联合疫苗抗原问无干扰,具有良好的安全性及免疫原性。     

Neurobiology of Stress-Induced Reproductive Dysfunction in Female Macaques

It is now well accepted that stress can precipitate mental and physical illness. However, it is becoming clear that given the same stress, some individuals are very vulnerable and will succumb to illness while others are more resilient and cope effectively, rather than becoming ill. This difference between individuals is called stress sensitivity. Stress sensitivity of an individual appears to be influenced by genetically inherited factors, early life (even prenatal) stress, and by the presence or absence of factors that provide protection from stress. In comparison to other stress-related diseases, the concept of sensitivity versus resilience to stress-induced reproductive dysfunction has received relatively little attention. The studies presented herein were undertaken to begin to identify stable characteristics and the neural underpinnings of individuals with sensitivity to stress-induced reproductive dysfunction. Female cynomolgus macaques with normal menstrual cycles either stop ovulating (stress sensitive) or to continue to ovulate (stress resilient) upon exposure to a combined metabolic and psychosocial stress. However, even in the absence of stress, the stress-sensitive animals have lower secretion of the ovarian steroids, estrogen and progesterone, have higher heart rates, have lower serotonin function, have fewer serotonin neurons and lower expression of pivotal serotonin-related genes, have lower expression of 5HT2A and 2C genes in the hypothalamus, have higher gene expression of GAD67 and CRH in the hypothalamus, and have reduced gonadotropin-releasing hormone transport to the anterior pituitary. Altogether, the results suggest that the neurobiology of reproductive circuits in stress-sensitive individuals is compromised. We speculate that with the application of stress, the dysfunction of these neural systems becomes exacerbated and reproductive function ceases.     

Comparative proteome analysis of thalamus in MK-801-treated rats

Two-dimensional gel-electrophoresis in combination with mass spectrometry is a powerful approach to compare protein expression in brain tissues. Using this proteomic approach, and based on the hypothesis that schizophrenia involves hypoglutamergic brain function, alterations in protein levels in the thalamus of rats treated with the N-methyl-D-aspartate (NMDA) receptor antagonist [+]-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]-cycloheptene-5,10-iminehydrogenmaleate (MK-801), as compared to saline-treated animals, were assessed in an unbiased fashion. The rats were divided into two groups; group 1 (short-term treated) and group 2 (long-term treated). In group 1, the levels of seven proteins were increased and four proteins reduced. In group 2, the levels of six proteins were reduced. Several of the altered proteins (heat shock proteins 60 and 72, albumin, dihydropyrimidinase related protein-2, aldolase c, and malate dehydrogenase) have previously been connected to schizophrenia. Alterations of other proteins (dihydrolipoamide acetyltransferase component of pyruvate dehydrogenase complex E2, guanine deaminase, alpha-enolase, aconitase, ATP-synthase and alpha-internexin), have not, to the best of our knowledge, earlier been implicated in schizophrenia pathology. Our results show the high potential of using proteomic methods for the validation of animal models of schizophrenia and to identify new proteins involved in the pathophysiological mechanisms of schizophrenia.     

Carotid ligation alters cholecystokinin-8 (CCK-8) immunoreactivity in gerbil brains

The unilateral or bilateral carotid arteries were ligated in gerbils used as a model of cerebral ischemia. The effect of different times of bilateral ischemia on the content of CCK-8 in fore regions of gerbil brain and the effect of 30 min of unilateral ischemia on the content of CCK-8 of the same regions in gerbils with or without neurological signs were observed. Our results show that the content of CCK-8 of cortex, basal ganglia, thalamus and hypothalamus decreased significantly. But, in brain stem it remained basically unchanged no matter whether the ischemia was unilateral or bilateral. This suggests that there is a close relationship between CCK-8 and cerebral ischemia, and raises the possibility that CCK-8 may be involved in cerebral ischemia through a yet unclear mechanism.     

Neuronal Nicotinic Receptors in Dementia with Lewy Bodies and Schizophrenia

Neuronal nicotinic receptors have been implicated in schizophrenia on the basis of the high incidence of tobacco smoking in patients, abnormalities in cytisine and alpha-bungarotoxin (alphaBGT) binding in the hippocampus, and linkage between auditory P50 deficits and the region of chromosome 15 coding the alpha7 subunit. In another disease associated with psychosis, dementia with Lewy bodies (DLB), in which visual hallucinations predominate, reductions in nicotine binding have been identified in various cortical and subcortical regions. We investigated both alphaBGT and nicotine binding autoradiographically in different thalamic nuclei in autopsy brain tissue from patients with schizophrenia and DLB. AlphaBGT binding in the reticular nucleus was moderately reduced (25%) in schizophrenia and more extensively reduced (50%) in DLB. There were no significant alterations in nicotine binding in schizophrenia, and in DLB, a trend towards moderate reductions in most nuclei reached significance in the lateral dorsal nucleus. It is concluded that widespread abnormalities of thalamic nicotine are not implicated in schizophrenia or DLB, but that reticular alphaBGT binding may be involved to a lesser and greater extent in the pathophysiology or psychopathology of both disorders.     

Developmental susceptibility of neurons to transient tetrahydrobiopterin insufficiency and antenatal hypoxia–ischemia in fetal rabbits

Tetrahydrobiopterin (BH₄) is important for normal brain development as congenital BH₄ deficiencies manifest movement disorders at various childhood ages. BH₄ transitions from very low levels in fetal brains to higher “adult” levels postnatally, with the highest levels in the thalamus. Maternal supplementation with the BH₄ precursor sepiapterin reduces postnatal motor deficits and perinatal deaths after 40-min fetal hypoxia–ischemia (HI) at 70% gestation, suggesting that brain BH₄ is important in improving function after HI. We tested the hypothesis that the intrinsically low concentrations of BH₄ made fetal neurons vulnerable to added insults. Brains were obtained from naïve fetal rabbits or after 40-min HI, at 70% (E22) and 92% gestation (E29). Neuronal cultures were prepared from basal ganglia, cortex, and thalamus, regions with different intrinsic levels of BH₄. Cultures were grown with or without added BH₄ for 48 h. Cell survival and mitochondrial function were determined by flow cytometry. At E22, thalamic cells had the lowest survival rate in a BH₄-free milieu, in both control and HI groups, whereas BH₄ supplementation ex vivo increased neuronal survival only in HI cells. Neuronal survival was similar in all regions without BH₄ at E29. BH₄ supplementation increased cell survival and cells with intact mitochondrial membrane potential, from basal ganglia and cortex, but not thalamus. After E29 HI, however, the benefit of BH₄ was limited to cortical neurons. We conclude that BH₄ is important for fetal neuronal survival after HI especially in the premature thalamus. Supplementation of BH₄ has a greater benefit at an earlier gestational age.     

Thiamine-like fibers in the monkey brain: an immunocytochemical study

The distribution of thiamine-immunoreactive structures was studied in the brain of the monkey using an indirect immunoperoxidase technique. Fibers containing thiamine, but no thiamine-immunoreactive cell bodies, were found. The highest density of fibers containing thiamine was observed in the pulvinar nucleus and in the region extending from the pulvinar nucleus to the caudate nucleus. In the mesencephalon, immunoreactive fibers containing thiamine were only found at rostral level close to the medial lemniscus (at the mesencephalic-diencephalic junction). In the thalamus, the distribution of thiamine-immunoreactive structures was more widespread. Thus, immunoreactive fibers were found in nuclei close to the midline (centrum medianum/parafascicular complex), in the ventrolateral thalamus (medial geniculate nucleus, inferior pulvinar nucleus), and in the dorsolateral thalamus (lateral posterior nucleus, pulvinar nucleus). Finally, in the anterior commissure and in the cerebral cortex a low density immunoreactive fibers was visualized. Thus, in the brainstem, no immunoreactive structures were visualized in the medulla oblongata, pons, or in the medial-caudal mesencephalon, and no immunoreactive fibers were observed in the cerebellum, hypothalamus and in the basal ganglia. The present report describes the first visualization and the morphological characteristics (thick, smooth and short, medium or long in length) of the thiamine-immunoreactive fibers in the primate central nervous system using an antiserum directed against this vitamin. The distribution of thiamine-immunoreactive structures in the monkey brain suggests that this vitamin could be involved in several physiological mechanisms.     

Some factors affecting the PTA staining of synaptic junctions

Summary An analysis has been made of the staining properties of phosphotungstic acid (PTA) on non-osmicated, glutaraldehyde fixed brain tissue, with regard to differences arising from the commercial source of the PTA, its water content, methanol as opposed to ethanol dehydration, and perfusion as contrasted with immersion fixation. The quality of the micrographs varied depending on the source of the PTA, the principal component of the synaptic junctions to be affected being the cleft material. Variation in the water content of the PTA solution was also reflected in the appearance of the cleft material, tissues stained with high hydration PTA resulting in cleft material with considerably less electronopacity than the corresponding dense projections and postsynaptic thickening. Low hydration PTA produced the typical picture of cleft densities. Methanol dehydration was unsuccessful in this series of experiments, while immersion and perfusion fixation yielded comparable results.Synaptic junctions from cerebral cortex, cerebellar cortex, thalamus, hippocampus and spinal cord of the rat were examined. In addition to the typical paramembranous densities, subjunctional bodies are present in cerebellar and hippocampal junctions, and subsynaptic profiles in some spinal cord ones. The spinal cord junctions are characterized by a prominent synaptic plate and by a postsynaptic thickening which in places appears to be separated from the underlying postsynaptic membrane.This work was supported in part by a grant from the Australian Research Grants Committee. I would like to thank Mr. R.F. Brearley for his excellent technical assistance, and Mr. D. Stuart and Mrs. Z. Gobby for their help with the photography.     

Axonal conduction properties of antidromically identified neurons in rat barrel cortex

Physiological studies of the rodent somatosensory cortex have consistently described considerable heterogeneity in receptive field properties of neurons outside of layer IV, particularly those in layers V and VI. One such approach for distinguishing among different local circuits in these layers may be to identify the projection target of neurons whose axon collaterals contribute to the local network. In vivo, this can be accomplished using antidromic stimulation methods. Using this approach, the axonal conduction properties of cortical efferent neurons are described. Four projection sites were activated using electrical stimulation: (1) vibrissal motor cortex, (2) ventrobasal thalamus (VB), (3) posteromedial thalamic nucleus (POm), and (4) cerebral peduncle. Extracellular recordings were obtained from a total of 169 units in 21 animals. Results demonstrate a close correspondence between the laminar location of the antidromically identified neurons and their anatomically known layer of origin. Axonal properties were most distinct for corticofugal axons projecting through the crus cerebri. Corticothalamic axons projecting to either VB or POm were more similar to each other in terms of laminar location and conduction properties, but could be distinguished using focal electrical stimulation. It is concluded that, once stimulation parameters are adjusted for the small volume of the rat brain, the use of antidromic techniques may be an effective strategy to differentiate among projection neurons comprising different local circuits in supra- and infragranular circuits.