Cingulate cortex response to electrical stimulation of the mediodorsal thalamic nucleus

Electrical stimulation of the lateral, parvocellular part of the mediodorsal thalamic nucleus of the rabbit was found to evoke field potentials and drive single cells in the anterior cingulate cortex. Furthermore, the laminar distribution of the field responses and the population of effected cells were dependent on the frequency of the stimulation. Excitatory current sinks were produced in layers I and III (primary layers of mediodorsal input) only when the stimulus frequency was in the theta range (6 to 8 Hz); the majority of cells were reliably driven only by stimulation within this range. Lower-frequency stimulation, e.g., 0.5 Hz, produced a current sink in layer V. Cells that were driven at low frequencies might be antidromically activated. The study suggests that modulation of mediodorsal outflow in the theta range may be necessary for effective information transfer to the cortex.     

血小板激活因子拮抗剂WEB2086对小鼠腹腔巨噬细胞释放肿瘤坏死因子的影响(英文)

小鼠ip3%TG 4天后取其腹腔巨噬细胞,血小板激活因子拮抗剂WEB 2086对LPS诱导的巨噬细胞释放肿瘤坏死因子(TNF)有显著的抑制作用。时效研究表明,TNF的产生和WEB 2086的抑制作用从LPS刺激后4 h开始,持续到22 h,在16 h时达到高峰。本文还首次采用一种用放线菌素D和NaF处理的L-929细胞测定TNF的新方法,此法与另外3种生物测定方法进行比较的结果显示此法具有更敏感、方便的特点。     

Dopamine action in the nucleus accumbens

The action of dopamine was studied in the nucleus accumbens of acutely prepared rabbits. Dopamine was applied iontophoretically to those cells and cell populations that responded in a monosynaptic excitatory manner to ipsilateral fimbrial stimulation. This strategy was adopted to isolate the effects of dopamine on postsynaptic receptors thus avoiding the bias resulting from activation of presynaptic dopamine receptors on dopaminergic afferents. Dopamine was found to have a suppressive effect on the excitatory (N) component of the field response and on driven extracellular unitary discharges. The specificity of dopamine's effect with receptors was indicated by the facts that fluphenazine effectively antagonized dopamine's effect, whereas bicuculline did not. The effect of dopamine was dependent on the rate of fimbrial stimulation. Dopamine has a marked suppressive effect on the fimbria-induced response at 0.5 Hz of stimulation but not at 6.0 Hz. This frequency specificity could not be linked directly to a cyclic adenosine 3',5'-cyclic monophosphate (cyclic AMP) mechanism because the iontophoresis cyclic AMP and dibutyryl cyclic AMP had suppressive effects at both 0.5 and 6.0 Hz rates of stimulation. It is suggested that dopamine acts in the nucleus accumbens to increase the "signal-to-noise" ratio. This might be a form of "contrast enhancement" of an incoming hippocampal message.     

商陆多糖Ⅰ联合白细胞介素2对小鼠脾细胞杀瘤活性的影响

商陆多糖Ⅰ（ＰＡＰ－Ｉ），０．３～３μｇ·ｍｌ－１和小鼠脾细胞培养３～５ｄ可显著增强其杀伤Ｐ８１５肿瘤细胞活性及ＩＬ－２（２５０～５００ＩＵ·ｍｌ－１）诱导的ＬＡＫ细胞活性，最适浓度为１μｇ·ｍｌ－１。ＰＡＰ－Ｉ及ＩＬ－２和脾细胞培养的上清液对Ｐ８１５肿瘤细胞无细胞毒作用，但能增强脾细胞及ＬＡＫ细胞杀瘤活性。ＰＡＰ－Ｉ，５，１０及５０ｍｇ·ｋｇ－１，ｉｐ可增强脾细胞杀伤Ｐ８１５和Ｌ９２９细胞的活性及ＩＬ－２诱导的ＬＡＫ细胞活性。     

赛庚啶对大鼠心肌细胞膜［~3H］－d－cis－硫氮卓酮结合部位的影响

苯并噻嗪类钙通道阻滞剂［３Ｈ］－ｄ－ｃｉｓ－硫氮酮能以一种特异和可饱和的方式与离体大鼠心肌细胞膜结合，其ＫＤ值和Ｂｍａｘ分别为８４ｎｍｏｌ·Ｌ－１和０．２７９ｐｍｏｌ·ｍｇｐｒｏｔｅｉｎ－１。非标记的硫氮酮和赛庚啶均能完全抑制这种结合，其Ｋｉ值分别为１０２ｎｍｏｌＬ－１和５．５ｕｍｏｌ·Ｌ－１。上述结果证实在大鼠心肌细胞膜上也存有［３Ｈ］－硫氮酮受体，同时还提示赛马庚啶对心肌细胞膜的钙通道阻滞作用可能与作用于心肌细胞膜［３Ｈ］硫氮酮受体有关。