Multitasking with neurotensin in the central nervous system

The 13-amino acid peptide neurotensin (NT) was discovered over 30 years ago and has been implicated in a wide variety of neurotransmitter and endocrine functions. This review focuses on four areas where there has been substantial recent progress in understanding NT signaling and several functions of the endogenous peptide. The first area concerns the functional activation of the high-affinity NT receptor, NTR-1, including the delineation of the NT binding pocket and receptor domains involved in functional coupling to intracellular signaling pathways. The development of NT receptor antagonists and the application of genetic and molecular genetic approaches have accelerated progress in understanding NT function in several areas, including the involvement of NT in antipsychotic drug actions, psychostimulant sensitization and the modulation of pain, and these are reviewed in that order. There is now substantial evidence indicating that NT is required for certain antipsychotic drug actions and that the peptide plays a key role in stress-induced analgesia.Received 18 March 2005; received after revision 9 May 2005; accepted 23 May 2005     

Regional brain [Met]-enkephalin in alcohol-preferring and non-alcohol-preferring inbred strains of mice

Summary Scrutiny of the data from these studies reveals that the C58/J alcohol-preferring mice have significantly lower baseline methionine-enkephalin levels in both the corpus striatum and hypothalamus compared to C3H/CHRGL/2 non-alcohol-preferring mice. In other brain regions in these two strains, specifically, pituitary, amygdala, midbrain, and hippocampus, analysis of methionine-enkephalin levels did not show any significant differences. This suggests that the hypothalamus may indeed be a specific locus involved in the regulation of alcohol intake, via the molecular interaction between neuroamines, opioid peptides, as they are influenced by genetics and environment.     

Both thermal and nociceptive afferents influence the unit activity of the neurons in the corpus striatum

Summary Both thermal and nociceptive stimulation in the periphery were shown to influence the neuronal activity recorded in the striatal area. Both the thermal and nociceptive sensitivity of the striatal neurons were closely related.The authors are grateful to the Alexander von Humboldt-Stiftung (Bad Godesberg, Bonn, Federal Republic of Germany) for donations of the necessary equipment for the present study. The research reported here was supported by grants from the National Science Council (Taipei, Taiwan, Republic of China)     

A new area in the brain associated with learning and memory

A new subdivision, named marginal division (MrD)> consisting of spindle-shaped neurons, has been identified at the caudomedial margin of the neostriatum in the brains of the rat, cat, monkey and human. It is distinguishable from the rest of striatum by special neural connections and many intensely expressed neuropeptides and some monoamines in the fibers, terminals and neuronal somata. Three-dimensional reconstruction of the rat brain reveals that the MrD is a flat pan-shaped area between the neostriatum and globus pal-lidus. Chemical lesions of bilateral MrD in rats will result in severely impaired learning and memory functions, as was demonstrated by double blind Y-maze test. The function of MrD has been shown to be associated with learning and memory by functional magnetic resonance imaging (fMRl) technique in human brain in vivo . Functional neuronal connections are observed between the MrD and hippocampus, amygdala, as well as the basal nucleus of Meynert by chemically induced c-Fos immunohistochemical staining. MrD is a newly discovered part and a universal structure in the neostriatum of the mammalian brain. MrD might very possibly play an important role in processes of the learning and memory.     

Neurosteroid enhances glutamate release in rat prelimbic cortex via activation of α1-adrenergic and σ1 receptors

The present paper studied the effect and mechanism of neurosteroid pregnenolone sulfate (PREGS) on spontaneous glutamate release using electrophysiological and biochemical methods combined with a pharmacological approach. The results suggested that PREGS had a selective enhancing effect on spontaneous glutamate release in the prelimbic cortex and the hippocampus but not in the striatum. The effect of PREGS in the prelimbic cortex appeared to be via modulation of ₁-adrenergic and ₁ receptors, but in the hippocampus it might be dependent on ₁ receptors only. The activation of ₁-adrenergic receptors synergized ₁ receptor activation in the prelimbic cortex. Intracellular calcium released from the endoplasmic reticulum, protein kinase C, adenylyl cyclase and protein kinase A played a key role in the effect of PREGS. Intracellular calcium, protein kinase C and adenylyl cyclase might be upstream events in the activation of protein kinase A after PREGS.Received 7 January 2005; received after revision 19 February 2005; accepted 22 February 2005 Available online 29 March 2005     

Evidence for an activating effect of tabernathine on rat brain catechlomine synthesis and elimination

Summary Tabernanthine increased the synthesis and elimination of catecholamines (CA) in the striatum and the rest of the brain, but not in the hypothalamus. These data provide evidence that tabernanthine may activate CA turnover of some brain structures by acting at 2 steps of the metabolic pathway. The results are discussed in relation to a central stimulating action and a hypoxia antagonistic effect of this drug.Acknowledgments. Tabernanthine was generously provided by the Institut de Chimie des Substances Naturelles of the C.N.R.S., Gifsur-Yvette, by B. Poiteau, Dat-Xuong, H. P. Husson, Mme Ch. Kan-Fan and P. Potier.     

琼枝和异枝麒麟菜中硫酸酯基多糖不同提取方法的化学分析比较

采用“直接水提法”以及“KCl分级法”来提取琼枝和异枝麒麟菜中的多糖．分别用蒽酮-硫酸法、间苯二酚法、明胶-BaCl2分光光度法测定多糖样品的总糖质量分数、3,6-内醚半乳糖质量分数、总硫酸基质量分数;用凝胶色谱法测定各多糖样品的相对分子质量分布情况：用GCMS测定麒麟菜硫酸酯基多糖的单糖种类及含量．结果显示采用“直接水提法”以及“KCl分级法”比传统的“碱处理法”产率高,而且硫酸基质量分数也明显增高．两种麒麟菜多糖均为硫酸酯基多糖,大部分都属于k-卡拉胶类．各多糖样品的相对分子质量分布在10^5左右．麒麟菜多糖主要是由半乳糖和3,6-内醚半乳糖组成,此外还含有少量的葡萄糖、木糖、塔罗糖和艾杜糖等,不同方法提取的多糖样品其单糖种类基本一致．     

游泳运动对大鼠纹状体、下丘脑多巴胺的含量及其代谢的影响

目的：探讨游泳运动对大鼠纹状体、下丘脑（DA）内多巴胺的含量及其代谢的影响.方法：选取72只雄性SD大鼠,随机分成6组：安静对照组（A）、一次性力竭游泳运动组（B）、安静＋水环境组（C）、游泳耐力训练组（D）、水环境组（E）、游泳耐力训练后一次性力竭游泳运动组（F）.D组按照耐力训练方案进行负重训练,每周5次,持续7周.所有大鼠一起断头处死,各组交叉进行,迅速取出脑组织（纹状体、下丘脑）进行多巴胺浓度和单胺氧化酶B（MAO-B）活性的测试.结果：一次性力竭运动或游泳训练对下丘脑中DA含量或MAO-B活性的影响无明显影响,而纹状体DA浓度在一次性力竭运动尤其是游泳训练后都明显升高（P〈0.05）,MAO-B也有升高的趋势.结论：一次性力竭运动尤其是游泳耐力训练使DA的浓度和MAO-B活性增加,其合成和分解代谢都增加,提高了DA的转换率,以适应运动的需要,有利于改善脑机能,延缓运动疲劳,是适应运动的表现.     

大鼠脑组织腺苷含量的HPLC分析

用高效液相色谱（ＨＰＬＣ）配紫外检测器，分离测定大鼠脑组织中腺苷含量。经实验确定以甲醇（１０％～６２％）、磷酸缓冲液（９０％～３８％）为流动相梯度洗脱，样品液中腺苷含量在２ｍｇ／Ｌ～１０ｍｇ／Ｌ范围内线性关系良好。加入标准样品的平均回收率为（９６６±２０）％。对６ｍｇ／Ｌ样品１０次重复测定结果的标准偏差为０１４，变异系数为３１％。对大鼠脑组织样品测定结果发现：与３～６月龄成龄鼠比较，１８～２０月龄老龄大鼠大脑皮层、海马、纹状体中腺苷含量分别增加了６６７％、３７２％和２７３％，不同脑区腺苷含量也有明显差异。结果提示不同脑区腺苷含量的随龄增加可作为研究衰老的一项指标；而中枢神经系统中随龄增长腺苷的堆积使Ａｃｈ释放受到抑制可能是出现记忆衰退等常见老年性功能障碍的一个重要原因     

Impaired auditory sensorimotor gating： An animal model of schizophrenia

Establishment of animal models of schizophrenia is critical for both understanding the mechanisms underlying this severe mental disease and developing new antipsychotics. This paper starts from the theoretical root of sensory gating, the 損rotection-of-processing? theory, then thoroughly describes the representative studies over the past decade on the mechanism underlying prepulse inhibition and on those underlying modulation of prepulse inhibition, which is the normal startle suppression caused by the weak stimulus preceding the intense startling stimulus. The main methods for inducing prepulse inhibition deficits in experimental animals include: ⅰ) modulations of neuro- transmission that are closely associated with schizophrenia; ⅱ) focal lesions or pharmacological manipulations of brain structures in the cortico-striato-pallido-pontine circuit; and ⅲ) maternal deprivation or social isolation. Six essential topics for studies in modeling schizophrenia are suggested at the last part of this review.