Functional activity of rat brainstem neurons regenerating axons along peripheral nerve grafts

To investigate activation and discharge patterns of central nervous system neurons that regenerate lengthy axons along peripheral nerve grafts we inserted a 4 cm long autologous segment of sciatic nerve into the dorsolateral medulla oblongata of adult rats. Two to 6 months after grafting, the distribution of the cells of origin of the regenerating axons in many nuclei of the brainstem was documented by retrograde horseradish peroxidase labelling from the cut end of the grafts. Functional properties of neurons regenerating axons into the grafts were studied by recording from single regenerated fibers teased from the grafts. Conduction velocities of graft fibers ranged from < 1m/s to 25m/s (30°C). Spontaneous centrifugal impulse traffic in the grafts included units firing in bursts synchronously with the respiratory cycle. Activity in other units was either elicited or inhibited by natural or electrical stimulation of the periphery. Most units recorded in the grafts were neither spontaneously active nor responsive to stimulation of primary afferents. We conclude that: (1) there are central nervous system neurons projecting into the grafts that respond to both excitatory and inhibitory transsynaptic influences; (2) at least some of the spontaneous and induced activity recorded from axons in the grafts resembles that known for normal nerve cells in the regions of the brainstem from which axonal growth arises; and (3) it is possible that many central neurons regenerating axons into peripheral nerve grafts have significantly reduced or altered synaptic inputs.     

RP-HPLC同时测定淡竹叶中4种黄酮苷的含量

目的：建立RP-HPLC同时测定不同产地、不同采收期淡竹叶中荭草苷、异荭草苷、牡荆苷、异牡荆苷的含量。方法：采用高效液相色谱法，Waters XBridge C₁₈色谱柱(4.6 mm×250 mm，5 μm)，以甲醇-0.05%冰醋酸(35∶65)为流动相洗脱，流速1.0 mL·min^-1，检测波长340 nm，柱温25 ℃。结果：4种成分均达到基线分离，线性关系良好。方法的平均回收率及RSD分别为荭草苷103.2%，2.1%；异荭草苷101.6%，2.7%；牡荆苷98.4%，2.3%；异牡荆苷99.2%，1.8%。结论：本研究所建立的HPLC方法操作简便、结果准确可靠，为该类药材的入药及资源利用提供了依据。     

淡竹叶化学成分与药理作用研究进展

目的：总结中药淡竹叶化学成分、药理作用的研究进展。方法：查阅并归纳有关淡竹叶化学成分、药理作用的文献并进行分析总结。结果：从淡竹叶中分离出黄酮类化合物、三萜类化合物、挥发性成分、酚酸类以及多糖、氨基酸和微量元素。淡竹叶具有抑菌、抗氧化、保肝、收缩血管、抗病毒、降血脂、心肌保护作用。结论：淡竹叶有多种药理作用,在临床及食品方面均有广泛应用,应将其化学成分与生物活性研究结合起来,更好地开发利用淡竹叶资源。     

Expression of brain-derived neurotrophic factor and TrkB receptor in the sudden infant death syndrome brainstem

This study compared the expression of BDNF (proBDNF and rhBDNF forms) and its receptor TrkB, in the medulla of sudden infant death syndrome (SIDS) infants and infants who died from known causes (non-SIDS). This study also evaluated these markers in association with SIDS clinical risk factors including, sleep position, cigarette smoke exposure and gender. Brainstem tissue was immunohistochemically stained and quantitative analyses were made for eight nuclei of the caudal and rostral medulla. Compared to non-SIDS, SIDS infants had lower rhBDNF in the caudal nucleus of the solitary tract and higher TrkB in the caudal dorsal motor nucleus of the vagus. Within the SIDS cohort, prone sleep position was associated with lower rhBDNF in the caudal arcuate nucleus, and cigarette smoke exposure was associated with lower rhBDNF and TrkB in the inferior olivary nucleus. Abnormal expression of BDNF and TrkB suggests that neuroprotective functions of the BDNF/TrkB system may be reduced in respiratory-related nuclei of SIDS infants.     

Neurogenesis of subpopulations of rat lumbar dorsal root ganglion neurons including neurons projecting to the dorsal column nuclei

The time of birth of subpopulations of dorsal root ganglion (DRG) neurons was studied with immunohistochemistry for 5-bromodeoxyuridine (BrdU). Pregnant rats were injected with BrdU i.p. to label the neurons on one of the embryonic days (E) E11-E16. When they were adults, the rats were given injections of Fluoro-Gold (FG) into the gracile nucleus to identify DRG neurons projecting to this structure. Following a 5 day survival period, the animals were perfused with aldehyde fixative. Sections from the L3-L5 DRGs were processed for BrdU immunohistochemistry followed by either immunostaining for the antineurofilament antibody RT97, as marker of the light neuronal subpopulation, or histochemical staining for the B4 isolectin from Griffonia simplicifolia I, as marker of the small dark subpopulation. The results indicated that the DRG neurons were generated between E12 and E16. The RT97⁺ neurons were generated on E12–E15, with a peak at E13. FG⁺ neurons, the majority of which were RT97⁺, were also generated on E12–E15. The B4⁺ neurons were generated on E13–E16, with a peak around E14. The overall pattern of neurogenesis of the DRG neurons showed that the RT97⁺ neurons were produced prior to the B4⁺ neurons. These findings are in agreement with earlier observations that the large DRG neurons are generated earlier than the small dark neurons. Our findings also suggest the existence of a third neuronal subpopulation that might be produced at the latest period of DRG neurogenesis at E15–E16. © 1996 Wiley-Liss, Inc.     

基于分子印迹技术分离淡竹叶中异荭草苷的研究＊

目的 利用分子印迹技术，建立一种制备异荭草苷分子印迹聚合物的方法，并将其用于中药淡竹叶中异荭草苷的分离研究。方法 本研究以异荭草苷为模板分子，2-乙烯基吡啶为功能单体，乙二醇二甲基丙烯酸酯为交联剂，通过沉淀聚合法制备印迹聚合物，对聚合物表面形态进行表征，研究聚合物的吸附与分离性能。结果 制备所得印迹聚合物对异荭草苷具有吸附能力和一定的分离能力，最大吸附量可达2.5 μmol·g^-1。结论 分子印迹聚合物可用于淡竹叶中异荭草苷的分离。     

淡竹叶茶的研究进展

淡竹叶在我国具有悠久的药用历史，近年来还被广泛的添加到各类食品中。淡竹叶的茎叶中主要含有黄酮类、挥发油类、酚酸类及少量萜类化合物，具有利尿、抗菌、抗氧化、抗炎、解热镇痛等活性，相关机制的研究也较为丰富。以淡竹叶等为原材料制成的凉茶在我国东南沿海地区已有悠久的饮用历史，在内陆省份也广受好评，具有较大的市场。对目前淡竹叶及其茶饮的相关报道进行综述，以期对后续淡竹叶茶的开发利用提供参考。