COMPARATIVE EFFECTS OF HYPOTHYROIDISM, HYPERTHYROIDISM AND UNDERNUTRITION ON THE PROTEIN AND NUCLEIC ACID CONTENTS OF THE CEREBELLUM IN THE YOUNG RAT

Abstract— The effects of hypothyroidism, hyperthyroidism and undernutrition on the development of the protein and nucleic acid contents of the cerebellum were studied in young rats ranging in age from 6 to 35 days. Foetal and neonatal propylthiouracil treatment caused a delayed cell multiplication in the organ but this delay had disappeared at 35 days. As early as the age of 10 days, the total cerebellar RNA and protein contents in these hypothyroid animals were lower than in the normal animals but the mean cellular contents of RNA and protein were not lowered before the age of 21 days. Slight neonatal hyperthyroidism, induced by the daily injection of a relatively small dose of thyroxine, produced an accelerated cell multiplication during the first postnatal week and afterwards a delay in cell proliferation. In the hyperthyroid animals, the mean cellular protein content, initially higher than normal, tended to be lower at 35 days. At this age, the cell number had nearly returned to normal. Undernutrition directly led to a reduced cell proliferation and the reduced cell number still persisted at 35 days. At first, the cells were on the average larger than normal, but the effect on the mean RNA and protein contents per cell was not persistent in the underfed animals.
This study correlates the degree of neonatal hyperthyroidism with the further development of the cell population of the cerebellum and emphasizes the importance of the events which take place just after birth in the cerebellum submitted to an excess or a deficiency of thyroid hormone. In addition, the results are discussed in relation to data concerning the morphogenetic action of thyroid and of underfeeding on the cerebellum.     

Effect of cholestanol feeding on sterol concentrations in the serum, liver, and cerebellum of mice

In order to elucidate the mechanism of xanthoma formation in cerebrotendinous xanthomatosis, mice were fed for 32 weeks with a diet rich in 5 alpha-cholestan-3 beta-ol (cholestanol) (1%, w/w). The concentrations of sterols in the serum, liver, and cerebellum were determined using high performance liquid chromatography. In the cholestanol-fed mice, the cholestanol concentrations in the serum and liver reached maxima in the first 2 to 4 weeks; the levels were about 30- to 100-fold higher than in the control diet mice. The cholestanol concentrations declined thereafter, finally to 50-60% of the maxima. Cholesterol concentrations were slightly lower in the cholestanol-fed mice throughout the experiments than in the control diet mice. On the other hand, the levels of cholestanol in the cerebellum increased almost linearly in parallel to the feeding time, and no decline was observed. These results suggest that the capacity of the liver to remove or degrade cholestanol was increased by long-term intake of this compound, whereas the cerebellum had no such feed-back regulation. Histological examinations using an electron microscope revealed the enlargement of lysosomal granules in the liver of the cholestanol-fed mice.     

THE DEVELOPMENT OF D-AMINO ACID OXIDASE IN RAT CEREBELLUM

D-Amino acid oxidase (D-amino acid: O₂ oxidoreductase (deaminating), EC 1.4.3.3; D-AAO) activity is biochemically undetected in rat brain stem, cerebellum and forebrain until 14 days after birth. Adult levels are attained by day 30 in the brain stem, and by day 36 in the cerebellum. At adulthood, forebrain D-AAO activity per g wet weight of tissue is less than 2% that of the cerebellum. In contrast to the pattern in the CNS, substantial D-AAO activity is present in both liver and kidney 2 days before birth and adult levels are approached within 2 weeks of birth. Nonetheless, D-AAO activities in rat liver, kidney, brain stem and cerebellum are likely to be due to a single enzyme which has properties very similar to the purified hog D-AAO. The late ontogenesis of D-AAO activity in cerebellum and brain stem relative to that in liver and kidney parallels reported phylogenetic data. Histochemical staining for D-AAO in rat cerebellar cortex is absent until 15 days after birth when activity is first observed in some cells of the external germinal zone and adjacent molecular layer. These cells appear to migrate to a final destination around the Purkinje cell soma and leave processes at the pial surface. By 21 days of age an adult pattern of staining is manifest throughout the cerebellum but it is of weak intensity. The adult pattern includes some staining in the granular layer which seems to be associated with mossy fibers and certain cerebellar glomeruli, and strong staining at the pial surface, in the molecular layer, and in cells surrounding, but not within, the Purkinje cell soma. The data suggest that the biochemical appearance of D-AAO in developing cerebellum derives from two sources: one associated with differentiation of one of the last cell types to form from the external germinal zone, and the other with maturation of mossy fibers and their synapses (cerebellar glomeruli).     

THE EFFECT OF GROWTH AND DEVELOPMENT ON THE PHOSPHOLIPIDS OF THE HUMAN BRAIN

Abstract— The phospholipid content and composition of the different regions of the developing human brain were studied. Brains from 25 fetuses and 9 infants, aged 13 weeks gestation to 26 months, were analysed. The concentration of total lipid-P was highest in the brain stem and lowest in the cerebellum at any age. Compared with the forebrain or brain stem, the cerebellum had a sharp phospholipid growth spurt between 3 months before and 6 months after birth. Before birth, the phospholipid pattern was similar in each part of the brain, with choline phosphoglycerides as the major phospholipid. After birth, the pattern in the brain stem changed further and ethanolamine phosphoglycerides became the dominant phospholipid, while in the other two there was little change. In all parts of the brain the proportion of sphingomyelin increased. The relative proportion of serine and inositol phosphoglycerides remained almost constant throughout the whole period of development. The possible significances of the changes in the phospholipids in neurological development are discussed.     

树突棘素在大鼠小脑中的表达和年龄变化

目的 观察树突棘素在大鼠小脑中的表达及年龄相关性变化。方法 应用免疫组织化学和Western blot方法,显示树突棘素在不同年龄组的大鼠小脑中的表达,并用图像分析系统对阳性免疫反应结果进行定量分析。结果 在中年组大鼠小脑中,树突棘素呈高表达,而在老年组和青年组大鼠小脑组织中表达水平相对较低。在小脑树突棘素的表达以分子层为主,其次表达在颗粒层细胞周围,少量树突棘素在大鼠小脑的蒲肯野细胞也有表达。结论 树突棘素的表达随着年龄的改变而变化;这种变化可能与不同年龄段大鼠小脑组织中突触的可塑性变化有关。     

LIPID DEFICIENCY IN THE CENTRAL NERVOUS SYSTEM OF LANDRACE PIGLETS AFFECTED WITH CONGENITAL TREMOR AIII, A FORM OF CEREBROSPINAL HYPOMYELINOGENESIS

—Congenital tremor, type AIII, is characterized by partial agenesis of the white matter of the CNS affecting mainly the spinal cord. The percentage water content of the fresh cord is consistently higher than normal and other parts of the CNS are sporadically affected. The total lipid content (mg/g fresh tissue) is markedly decreased in the cord but brain stem and cerebellum are less severely deficient; the cerebrum is barely deficient. Total amounts of cholesterol, cerebroside and phospholipid (mmol/part) are significantly reduced predominantly in cerebellum, brain stem and cord. Total DNA and protein contents are decreased to a significant extent only in spinal cord. Broadly similar lipid changes are found in fixed tissues. The data are consistent with sub-normal myelination, associated with a deficiency of oligodendrocytes.     

ACETYLCHOLINESTERASE IN THE FELINE CEREBELLUM

Histochemical procedures for the localisation of AChE have been used on the cerebella of normal and operated cats to investigate the presence of cholinergic pathways. The evidence indicates that some mossy afferent fibres and deep nuclear cells are cholinergic. The presence of AChE in many cells in the granule cell layer suggests that some parallel fibres and association pathways in the cerebellum may also be cholinergic. The relationship of these results to studies on the pharmacology and distribution of choline acetyltransferase in the cerebellum is discussed.     

THE RELATIONSHIP BETWEEN DNA SYNTHESIS AND NUCLEAR PROTEINS IN THE CEREBRUM AND CEREBELLUM OF 8-DAY-OLD RATS

In-8-day-old rats the higher rate of DNA replication in cerebellum than in cerebrum is accompanied by an enhanced synthesis of nuclear proteins. The greatest difference between the incorporation of tritiated leucine into proteins of cerebral and cerebellar cell nuclei occurs in the acid-soluble deoxyribonucleoproteins. However, the specific radioactivity of the acidic deoxyribonucleoproteins is similar in both tissues. The relative content of these proteins and the activity of the RNA polymerase is higher in cerebrum than in cerebellum. The results suggest that in the cerebrum of young rats these proteins are mainly concerned with the regulation of RNA synthesis.     

CEREBELLAR DEVELOPMENT IN THE RAT AFTER EARLY POSTNATAL DAMAGE BY METHYLAZOXY-METHANOL: DNA, RNA AND PROTEIN DURING RECOVERY

—Total cerebellar DNA, RNA, protein and wet weight were determined for normal cerebellum and for cerebellum damaged early in postnatal development by the neurotoxic action of the drug methylazoxymethanol (MAM) acetate. Injections of a 10 mg/kg dose of the drug were given on postnatal days 1, 2, 3 and 4 as a means of inducing a transient insult to the proliferating stem cell population of the external granular layer. Cerebellar DNA and other quantitative measures were reduced to 50 per cent of normal at day 7. Growth in the MAM-treated cerebellum was relatively more rapid than in normals so that the eventual deficit in the adult was 80 per cent of normal. We concluded that early postnatal transient injury of the developing cerebellum is followed by a regenerative phase of repair but that quantitatively significant mitosis in the injured cerebellum ceases normally at about post-natal day 17. The conditions evaluated in this investigation may serve as a model for other types of injury induced by drugs, irradiation, viruses or nutritional factors.     

Endocrine cells share expression of N-CAM with neurones

The expression of the neural cell adhesion molecule, N-CAM, was examined in the anterior lobe of rat hypophysis by immunocytochemistry at light and electron microscope levels. In addition, N-CAM antigenic determinants present in adrenal medulla, anterior hypophysis and PC12 cells were compared by immunoblotting with those found in cerebellum. All secretory cells in the anterior hypophysis were found to be N-CAM positive on their surfaces, but not all of the three polypeptide determinants typical of cerebellum were present in the endocrine tissues or cell line tested. In addition, a new N-CAM determinant of 49 kDa not present in cerebellum was found in adrenal medulla and hypophysis, although it was absent from PC12 cells. The possible implications of these data are discussed.     

SILVER DEPOSITION IN THE CENTRAL NERVOUS SYSTEM AND THE HEMATOENCEPHALIC BARRIER STUDIED WITH THE ELECTRON MICROSCOPE

For the purpose of studying the hematoencephalic barrier as it is concerned with silver circulating in the blood stream, silver nitrate was vitally administered to rats in their drinking water over periods of 6 to 8 months. The cerebrum, cerebellum, medulla, area postrema, and choroid plexus were prepared for light and electron microscopy. Silver deposition was found in the perivascular spaces in the choroid plexus, area postrema, in the medulla surrounding the area postrema, and in minute quantities in the cerebrum, cerebellum, and most of the medulla. Two levels of the hematoencephalic barrier were apparently demonstrated in our investigations. The endothelial linings of the vessels in the cerebrum, cerebellum, and medulla constitute the first threshold of the hematoencephalic barrier (specifically here, blood-brain barrier). The cell membranes adjacent to the perivascular spaces form the second threshold, as follows:—the neuroglial cell membranes in the cerebrum, cerebellum, and medulla (blood-brain barrier); the membranes of the neuroglial cells in the area postrema (blood-brain barrier); and the membranes of the epithelial cells of the choroid plexus (blood-cerebrospinal fluid barrier). This study deals with silver deposition and does not infer that the penetration of ionic silver, if present in the blood stream, would necessarily be limited to the regions described. Bleb-like structures were observed to cover the epithelial cell surfaces in the choroid plexus. They may be cellular projections increasing the cell surface area or they may be secretory droplets.     

NF200在猫小脑中的分布及其老年性变化

目的探讨NF200（神经丝蛋白-200）在猫小脑中的分布及其老年性变化,以及导致相关变化的原因与在小脑功能衰老中的意义。方法利用Nissl染色显示小脑内部结构和神经元,免疫组织化学ABC法标记NF200免疫阳性（NF200-IR）结构。光镜下观察,采集图像,并利用Image-Pro Express5.1图像分析软件对小脑中NF200免疫阳性神经元以及各层免疫阳性反应灰度值进行分析统计。结果NF200免疫阳性神经元主要分布于蒲肯野细胞层和分子层底部,阳性纤维及终末在青年猫和老年猫小脑各层均有分布。与青年猫相比,老年猫蒲肯野细胞层神经元密度及其各层NF200免疫阳性反应强度均显著下降（P〈0.01）;蒲肯野细胞的胞体萎缩,阳性树突分枝明显减少。结论衰老过程中猫小脑NF200含量的下降,导致细胞结构紊乱,轴浆运输能力下降,可能是老年个体小脑功能衰退的重要原因之一。     

安徽大别山分水岭地带植物花粉形态研究

应用光学显微镜和扫描电镜对安徽大别山分水岭鹞落坪自然保护区7月份开花的32科52种3变种植物的花粉形态进行了观察和研究,提供了花粉图谱、植物生长习性和地理分布范围,为地层中的化石花粉鉴定提供标准图谱和相关信息。对该区域植物的生态因子,包括地理位置、分布范围、海拔高度、年降水量、年积温和生境进行归纳总结,确定该区域的花粉形态综合特征与气候和环境之间可能的联系,为地层孢粉研究提供现代孢粉学依据。     

THE FINE STRUCTURE OF THE PURKINJE CELL

This paper describes the fine structure of the Purkinje cell of the rat cerebellum after fixation by perfusion with 1 per cent buffered osmium tetroxide. Structures described include a large Golgi apparatus, abundant Nissl substance, mitochondria, multivesicular bodies, osmiophilic granules, axodendritic and axosomatic synapses, the nucleus, the nucleolus, and the nucleolar body. A new and possibly unique relationship between mitochondria and subsurface cisterns is described. Possible functional correlations are discussed.     

SPECIALIZED MEMBRANE JUNCTIONS BETWEEN NEURONS IN THE VERTEBRATE CEREBELLAR CORTEX

"Gap" junctions, the morphological correlate for low-resistance junctions, are demonstrated between some mossy fiber terminals and granule cell dendrites in some lower vertebrate cerebella (gymnotid and frog). Most of the gap junctions (GJs) seen in the gymnotid-fish cerebellum exhibit an asymmetrical configuration, the electron-opaque cytoplasmic material underlying the junction being more extensive in the dendritic than in the axonal side. In the frog cerebellum, the GJs have a symmetrical distribution of such electron-opaque material. In both species the GJs are encountered at the same synaptic interface as the conventional synaptic zone (CSZ), constituting "mixed synapses" in a morphological sense. The axonal surface covered by CSZs is larger than that covered by GJs. In mammalian cerebellum, GJs are observed only in the molecular layer, between perikarya, dendrites, or perikarya and dendrites of the inhibitory interneurons. These GJs are intermixed with attachment plates and intermediary junctions interpreted as simply adhesive. In the mammalian cerebellum, a new type of junction which resembles the septate junctions (SJs) of invertebrate epithelia is observed between axonal branches forming the tip of the brush of basket fibers around the initial segment of the Purkinje cell axon. It is suggested that such junctions may be modified forms of septate junctions. The physiological implications of the possible existence of high-resistance cross-bridges between basket cell terminals, which may compartmentalize the extracellular space and thus regulate extracellular current flow, must be considered.     

中华绒螯蟹成熟卵形态和超微结构的研究

中华绒螯蟹的成熟卵仅有初级卵膜，无次级和三级卵巢，质膜初期厚而多层，且具皱褶，卵核在卵的发育过程中变化很大，未发见中心粒，内质网和高尔基体均始见于蟹卵发育的初期，皮层颗粒先出现于蟹卵深部，随后移到卵的表层，无滋养细胞，蟹卵由卵泡细胞提供物质，形成卵黄，此外，还可直接从血淋巴内摄取卵黄前身物质。     

雌激素替代治疗对大鼠小脑树突棘素表达的影响

目的研究雌激素替代治疗对大鼠小脑树突棘素表达的影响。方法实验选取SD大鼠制作卵巢切除雌激素替代模型,以免疫组织化学,Western blot观察大鼠小脑中树突棘素的表达及其变化。结果免疫组化检测显示：树突棘素存在于小脑的分子层和颗粒层,蒲氏细胞胞浆中也可见的阳性颗粒。假手术组树突棘素阳性略强于雌激素替代组,但无统计学差异：手术安慰剂组中树突棘素阳性显著弱于其他二组。Western blot结果表明：树突棘素在安慰剂组大鼠小脑中表达最低,与其它二组有显著性差异,假手术组和雌激素替代组中树突棘素的表达量无显明差异。结论雌激素对维持大鼠小脑树突棘素的正常水平具有重要的作用。     

CONTRIBUTION OF THE PENTOSE CYCLE TO THE METABOLISM OF GLUCOSE IN THE ISOLATED, PERFUSED BRAIN OF THE MONKEY

Abstract— Isolated brains from three adult monkeys were perfused for 1 hr with [2-¹⁴C]glucose. Glycogen was isolated from the brain stem, cerebral hemispheres, cerebellum and the hypothalamic area at completion of the perfusions. The distribution of ¹⁴C in carbons of the glucose unit of glycogen was determined and from this the contribution of the pentose cycle to metabolism of glucose was calculated. The data indicate a maximum contribution by the pentose cycle of 5–8 per cent in brain. No significant difference was observed in the various portions of brain. Oxygen consumption was noted to be low in relation to the amount of glucose utilized, as measured in these experiments.     

电刺激蝙蝠小脑对中脑上丘神经元听反应的影响

实验在２３只成年中华鼠耳蝠（Ｍｙｏｌｉｓｃｈｉｎｅｎｓｉｓ）上进行。使用常规电生理学方法,观察了电刺激小脑对上丘神经元听反应的影响。在所观察的１７１个上丘神经元中,有１１６个（占６７．８４％）神经元听反应受到影响,其中７２个（占４２．１１％）表现为抑制效应,４４个（占２５．７３％）为易化效应。刺激小脑对上丘神经听反应的影响是双侧的。抑制或易化程度与电刺激强度、声刺激强度以及声、电刺激间隔有关。结果提示,小脑可以对上丘神经元听反应进行调制,这种调制作用可能是小脑调控回声定位过程中听觉－运动的中枢机制之一。