老年学习记忆减退大鼠齿状回突触的定量研究

据老年大鼠在Ｍｏｒｒｉｓ水迷宫中的行为表现，将其分为老年学习记忆减退和学习记忆正常两部分，采用透射电镜观察、拍片，对齿状回中分子层触的数量和大小进行体视学定量分析。     

Multiple forms of glycoproteins in the secretory product of the bovine subcommissural organ--an ancient glial structure

The glial subcommissural organ (SCO) is a conserved structure of the vertebrate brain that secretes a glycoprotein-rich product into both the extracellular matrix and the cerebrospinal fluid of the third ventricle that forms Reissner's fibre (RF). In order to identify specific secretory proteins of the subcommissural organ, a panel of antigen- and epitope-specific monoclonal antibodies was raised against bovine RF to study the distribution of epitopes in Western blots of bovine RF. Six groups of epitopes that were specific for SCO secretion were distinguished on the basis of their phylogenetic conservation and their different grades of resistance against chemical denaturation. The monoclonal antibody aRFME 4 recognised a carbohydrate-containing epitope that was strongly conserved in vertebrates and unique for SCO secretion. All epitopes showed essentially the same distribution pattern over 15 bovine RF glycoprotein fractions of different molecular masses in immunoblots indicating that the different RF fractions are closely related. They may represent multiple forms of SCO spondin.     

大鼠中缝大核突触囊泡在电针后的变化及其图象分析

应用透射电镜和图象分析方法,对电针后大鼠中缝大核突触前终扣内突触囊泡的数量以及突触前终扣内容物的量的变化进行了研究。结果表明:电针后,中缝大核突触前终扣内圆形清亮囊泡和颗粒囊泡的数量明显减少,突触囊泡聚集并向突触活性带集中。图象分析结果:电针后,突触前终扣内容物的量较对照组明显减少,而且内容物分布不均匀并在突触膜附近集中。本实验为针刺镇痛的理论研究提供了形态学依据。     

Reduction of FK-506 requirements by combination with polyethylene glycol superoxide dismutase in orthotopic rat liver transplantation

Reperfusion after ischemia results in endothelial cell injury and Kupffer cell activation. Inflammatory cytokines thus released can induce major histocompatibility complex antigens and increase the immunogenecity of the graft. An orthotopic rat liver allotransplant model was used to test the hypothesis that prevention of reperfusion injury by infusion of polyethylene glycol superoxide dismutase (PEG-SOD) would result in long-term allograft survival in the presence of subthreshold immunosuppressive dosages. ACI rats were used as donors, and Lewis strain rats as recipients. Orthotopic liver transplantation was initially performed to identify a subthreshold dose of the immunosuppressant FK-506, which would be unable to extend survival longer than control untreated rats with this strain combination. After testing three intramuscular FK-506 doses of 0.04, 0.08, and 0.16 mg/kg, it was observed that an FK-506 dose of 0.04 mg/kg/day for 14 days was unable to extend survival longer than in untreated recipients. This dose of FK-506 was used in combination with PEG-SOD at doses of 1000, 3000, 10,000, or 30,000 units. Recipient animals were treated intravenously with PEG-SOD as a loading dose to facilitate tissue penetration on day 1, and beginning on the day of transplantation, every 2 days for the duration of the study. Results of histologic studies and mean survival time were compared in untreated recipients and in rats treated with PEG-SOD plus 0.04 mg/kg/day FK-506. Mean survival time was increased significantly in these animals (p < 0.007) to 40.6 ± 25.6 days as compared with either untreated rats (10.0 ± 2.7 days) or rats treated with 0.04 mg/kg FK-506 alone (13.7 ± 4.2 days). Histologic examination demonstrated a significant reduction in the cellular infiltrate in rats treated with PEG-SOD plus FK-506, as compared with recipients treated with either agent alone or left untreated. Our results therefore suggest a potential approach to reducing immunosuppression in transplantation. (J ALLERGY CLIN IMMUNOL 1995;95:1276-81.)     

Immunoreactive somatostatin-28(1-12) is increased in Huntington's disease

Somatostatin-28(1-12) concentrations were measured in Huntington's disease (HD) postmortem tissue using a specific radioimmunoassay. Concentrations of immunoreactive somatostatin-28(1-12) were significantly increased in the caudate and putamen but were unchanged in cortical areas A9 and A17. Since somatostatin-28(1-12) terminates with the amino acids Arg-Glu-OH, we examined whether this dodecapeptide compound might exert a neurotoxic effect. Injections of somatostatin-28(1-12) into rat striatum showed no evidence of histologic damage.     

Development of pump electrogenesis in hypokalaemic rat muscle

In hypokalaemic rats maintained on a potassium deficient diets for 10–50 days, the isolated Na-loaded and K-depleted (Na-rich) muscle fibers showed the membrane potential less than –115 mV in fresh muscles of normal rats in K⁺-free Krebs solution. Upon adding 5 mM K⁺ to the K⁺-free medium bathing the soleus muscles, the measured potentials of Na-rich muscles always exceeded the membrane potentials of fresh muscles in 5 mM K⁺. The hyperpolarization was dependent on the amount of intracellular Na⁺ concentration ([Na]_i) accumulated during the potassium deficiency. The electrogenic Na-pump was activated by an increase of [Na]_i of less than 5 mM. Further increases in [Na]_i resulted in increases in membrane potential which appeared to approach a limit at [Na]_i levels higher than 65 mM.     

Validation and advantages of FAWSETS perfusion measurements in skeletal muscle

This work discusses the strengths, limitations and validity of a novel arterial spin labeling technique when used specifically to measure perfusion in limb skeletal muscle. The technique, flow-driven arterial water stimulation with elimination of tissue signal (FAWSETS), offers several advantages over existing arterial spin labeling techniques. The primary goal of this study was to determine the perfusion signal response to changes in net hind limb flow that were independently verifiable. The range of perfusate flow was relevant to skeletal muscle during mild to moderate exercise. Localized, single voxel measurements were acquired from a 5 mm-thick slice in the isolated perfused rat hind limb at variable net flow rates. The results show that the perfusion signal is linearly proportional to net hind limb flow with a correlation coefficient of 0.974 (p = 0.0013). FAWSETS is especially well suited for studies of skeletal muscle perfusion, where it eliminates the need to compensate for magnetization transfer and arterial transit time effects. A conceptual discussion of the basic principles underlying these advantages is presented.     

Cellular and subcellular localization of the small G protein RhoA in the human and rat embryonic and adult kidney

Rho proteins, a subgroup of the Ras GTPase superfamily, control many cellular processes and morphogenetic events by acting as signaling molecules in the transduction pathways of various receptors. Among the "Rho-dependent" receptors are the extracellular matrix- and growth factor-binding sites; these are particularly involved in the modulation of renal development since they control the epithelial-mesenchymal interactions that drive kidney organogenesis. The present study has addressed the immunohistochemical localization of RhoA in developing and adult kidneys of rats and humans because: a) Rho proteins are known to have a morphogenetic role, b) data in the literature on expression of Rho GTPases during mammalian histogenesis and organogenesis are scarce, and c) their involvement in the transduction pathways of receptors is implicated in kidney development. In particular, RhoA peptide was found to be localized in the mesonephric duct and vesicles in both rats and humans; metanephric anlagen were mainly stained in ampullar-derived cells. Periglomerular tubules of fetal and adult kidneys as well as collecting ducts of adult kidneys showed intense staining. Therefore, the present study provides new information on the distribution patterns of RhoA during early stages of mammalian kidney development suggesting that this signaling molecule may take part in epithelial-mesenchymal induction processes that control kidney organogenesis. RhoA expression in adult structures may be linked with renewal of renal epithelial cells and the maintenance of their morphology and polarity.     

Neuraminidase- and benzalkonium chloride-dependent inhibition of basic peptide-induced rat mast cell secretion

Two types of inhibition of basic peptide-induced rat mast cell secretion are reported. Pretreatment of rat peritoneal mast cells with Vibrio comma neuraminidase, an enzyme which cleaves sialic acid from oligosaccharides, led to inhibition of 5-hydroxytryptamine release induced by the basic peptides polylysine, corticotropin_1–24 and a decapeptide sequence of human IgE. Inhibition was similarly observed when mast cells were challenged in the presence of the cationic cell membrane-active substance benzalkonium chloride. It is postulated that both of these experimental procedures inhibit basic peptide-induced secretion by depletion of cell surface negative charge. Sialic acid itself does not act as a specific receptor for basic peptides, since a molar excess of sialic acid in free solution failed to inhibit secretion by binding to basic peptides in the fluid phase.     

Estrogen stimulates neuronal plasticity in the deafferented hypothalamic arcuate nucleus in aged female rats

The hypothalamic arcuate nucleus (ARCN) was examined ultrastructurally 3 weeks after the complete deafferentation of the medial basal hypothalamus (MBH) with the island isolation technique in ovariectomized aged female rats (720-930 days of age). The mean numbers of axodendritic and axosomatic synapses in the ARCN decreased to about one-third of those in the intact controls. However, the treatment with estradiol benzoate (2 micrograms/day) during the 3 weeks following the day of brain surgery brought about a marked increase in the numbers of these synapses. The data suggest that the ARCN neurons of aged female rats still retain plasticity to react to deafferentation under influences of estrogen.