大鼠蓝斑内注入谷氨酸钠的心血管效应及其中枢机制

本工作在乌拉坦麻醉、箭毒化、人工呼吸的大鼠观察到:(1)将 L-谷氨酸钠(Glu)微量注入蓝斑(LC)引起血压升高,心率无明显变化;注入 LC 邻近区引起血压降低、心率减慢。(2)在下丘脑的室旁核尾侧断脑可衰减 LC 加压效应,而室旁核头侧断脑对 LC 加压反应无明显影响,双侧延髓头端腹外侧区(RVL)内分别注射酚妥拉明、心得安、阿托品均使兴奋 LC 引起的加压效应衰减;提示蓝斑加压效应由室旁核和 RVL(及其内的α-、β-肾上腺素能受体,M-胆碱能受体)介导。     

Chloride channels in the nuclear membrane

Summary Chloride-selective ion channels were measured from isolated rat liver nuclei. Single ion channel currents were recorded in both nuclear-attached and in excised patches in the insideout configuration of the patch-clamp technique. Two types of chloride conductance were defined, a large conductance (150 pS;i _Cl.N ) channel with complex kinetics and multiple substates, and a second smaller conductance (58 pS;I _Cl.n ) channel sensitive to block by ATP. The channels were inhibited by pharmacological agents known to block chloride channels and were insensitive to internal and external changes in calcium and magnesium. Presumably the channels reside in the external membrane of the nuclear double membrane and may mediate charge balance in the release and uptake of calcium from the perinuclear space.     

Staining of Nuclei in Fungi by Ethidium Bromide

Ethidium bromide, (0.1% solution in ethanol-water, 1:3, v/v) was used to stain nuclei in mycelia and spores of different fungi. Nuclei looked bright brick red under green excitation. This method is very efficient, specific, reproducible and cost-effective.     

Effects of osmotic shock on the ultrastructure of cell nuclei in euryhaline and stenohaline crustaceans

Changes in cell ultrastructure in relation to volume regulation following application of osmotic challenges have been but poorly documented up to now. In a previous study, we demonstrated that large and immediate changes in the organization of nuclear chromatin occur in mammalian cells under such conditions. Similar chromatin modifications are shown in the present study in the cells of the stenohaline crab Maia verrucosa. They are not seen in the cells of the euryhaline species tested, hyperosmoregulating (Eriocheir sinensis) or osmoconforming (Cancer pagurus). Nor are they seen in cells of Portunus puber, another stenohaline species. These results are discussed in the context of the disrupting effects that inorganic ions have on macromolecular structures and of the protection which may be conferred by organic osmolytes used by various crustacean species.     

Characterization of Extracellular Histamine in the Striatum and Bed Nucleus of the Stria Terminalis of the Rat: An In Vivo Microdialysis Study

The intracerebral microdialysis technique, coupled with a sensitive radioenzymatic assay, was employed to study histamine release in the striatum and in the bed nucleus of the stria terminalis (BNST) in conscious, freely moving rats. In these brain regions, extracellular histamine concentrations decreased by 20% when calcium was omitted from the perfusion solution. Extracellular histamine was insensitive to the addition of tetrodotoxin to the perfusion medium. In striatum, extracellular histamine concentrations declined in an apparent biexponential manner after the administration of alpha-fluoromethylhistidine, an inhibitor of histamine synthesis. The half-lives for the disappearance of histamine were 32 min and 7.7 h, indicating the presence of at least two histamine pools. Histidine loading resulted in a nearly twofold increase in histamine outflow in striatum. In the BNST, yohimbine increased the extracellular histamine content by 50%, suggesting that histamine release is subject to alpha 2-adrenergic regulation in vivo. The extent to which histamine detected in cerebral microdialysis samples is of neurogenic origin remains to be established.     

单胺类受体阻断剂和纳洛酮对家兔脊髓下行性抑制作用的影响

实验在27只麻痹的清醒家兔上进行。用玻璃微电极记录丘脑束旁核单位对腓总神经伤害性刺激发生的痛敏放电情况。这种痛敏放电活动均能无例外地被模拟的下行性抑制、即用弱电流刺激分离的脊髓背侧1/2外周端所抑制。在27个单位中,静注α-肾上腺能受体阻断剂酚妥拉明后,有16个单位的脊髓刺激的抑制效应被明显削弱,11个单位的脊髓刺激效应基本无变化。在5个酚妥拉明有效的单位,待药物作用消失之后,其脊髓刺激效应均能被纳洛酮所阻断。在5个脊髓刺激效应不受酚妥拉明影响的单位,静注5-羟色胺受体阻断剂賽庚啶后,有4个单位的脊髓刺激效应被明显削弱;而另外一个单位的脊髓刺激效应依然存在。以上实验结果提示,经由脊髓背侧下行、在脊髓水平对痛信号进行调制的下行通路可能主要包括两类纤维系统,一类以去甲肾上腺素(通过α受体发挥作用)和内源性吗啡样物质为递质或/和调制物,另一类则以-5羟色胺为递质。这两类纤维可能分别影响不同的脊髓背角上行投射神经元。     

尾核内注入GABA、Picrotoxin对家兔食物性运动条件反射的影响

于家兔尾核头部分别注入γ-氨基丁酸(GABA)3mg/5μl、GABA 转氨酶的抑制剂氨氧乙酸(AOAA)10μg/5μl 及 GABA 受体阻断剂印防已毒素(Picrotoxin)0.5μg/5μl 后,可暂时抑制食物性条件反射的出现,但一般运动、摄食等机能无明显障碍。作为对照,在尾核头部注入生理盐水或士的宁不影响条件反射的出现,注射 Picrotoxin 等于内囊区及海马也不影响条件反射活动。实验结果表明,尾核头部 GABA 能突触传递与实现条件反射活动有关。     

Thermosensitivity of the preoptic region and the spinal cord in the golden hamster

1. 1.|The effects of thermal stimulation of the preoptic region (POAH) and the spinal cord on non-shivering thermogenesis (NST) and shivering were studied in euthermic golden hamsters.

2. 2.|Shivering intensity is suppressed by heating the POAH but is independent of spinal cord temperature. Therefore, NST in the interscapular brown adipose tissue does not suppress shivering.

3. 3.|NST is inhibited by heating of the POAH as well as of spinal cord. It is discussed that the control of NST by two different central thermosensitive areas is significant for thermoregulation during exercise.

γ-Aminobutyric Acid Can Both Inhibit and Facilitate Dopamine Release in the Caudate Nucleus of the Rabbit

Abstract: Slices from rabbit caudate nucleus were preincubated with [³II]dopamine and then superfused and stimulated electrically. y -Aminobutyric acid IW4 and moYL increased both the basal and the stimulation-evoked overflow of tritium. The effects were not changed by picrotoxin and were only slightly reduced by bicuculline. In the presence of nipecotate mol/L, y-aminobutyric acid decreased rather than enhanced the basal and the evoked overflow. The inhibition persisted in the presence of bicuculline. Muscimol did not affect, whereas baclofen decreased, the evoked overflow of tritium. Similar results were obtained with synaptosomes that were stimulated by 30 mmoVL K'. The results indicate that y -aminobutyric acid can both facilitate and depress the release of dopamine. Facilitation occurs after entry of y -aminobutyric acid into the dopaminergic terminal axons, whereas inhibition is probably mediated by a receptor site located in the membrane of these terminals.     

Two possible actions for circulating angiotensin II in the control of vasopressin release

The supraoptic-hypophyseal tract is a primary system for the synthesis and release of vasopressin. Angiotensin II (AII) has been shown to release vasopressin when injected into the cerebral ventricles (IVT). However, intravenous (IV) AII injections have not produced consistent results. The present studies were conducted to examine the effects of AII delivered by either route on the unit activity of supraoptic nucleus (SON) magnocellular neurons. Rats were prepared with intracranial cannulas to insure delivery of drugs to the left lateral ventricle and with polyethylene catheters in the left jugular vein, femoral vein, and femoral artery for systemic injections and arterial pressure recordings. A ventral approach permitted recording from the SON without violating the ventricular-SON partition. Magnocellular neurons were electrophysiologically identified. In the majority of identified cells, IVT AII increased activity. In others pressor doses of AII IV inhibited firing while blood pressure was elevated. After sino-aortic denervation, AII IV excited SON neurons. Based on latency, and the fact that lesioning the anteroventral third ventricle blocked the action of AII IVT, the results indicate that AII IVT acts on a periventricular site to influence SON magnocellular neurons. Furthermore, systemic AII may have two effects on SON neurons: a central excitatory action, and an inhibition due to a baroreceptor reflex.