Immunocytochemical distribution of met-enkephalin-Arg6-Gly7-Leu8 in the rat lower brainstem

The distribution of methionine-enkephalin-Arg6-Gly7-Leu8, a unique peptide derived from proenkephalin A in the rat brainstem, was studied immunocytochemically by using a highly specific antiserum to this octapeptide sequence. Immunoreactive perikarya with various shapes and sizes were detected in many regions of the rat brainstem. Dense accumulation of immunoreactive perikarya and fibers was seen in the nuclei associated with special sensory and visceral functions, such as the interpeduncular nucleus, the parabrachial nucleus, the nucleus of the solitary tract, and the nucleus of the spinal tract of the trigeminal nerve. Clusters of methionine-enkephalin-Arg6-Gly7-Leu8-like immunoreactive perikarya and fibers were observed in certain areas considered to play a role in nociception and analgesia, such as the central gray of the midbrain central gray and the raphe magnus nucleus. Some methionine-enkephalin-Arg6-Gly7-Leu8-like immunoreactive perikarya were distributed in the lateral reticular nucleus, the nucleus of the solitary tract, and the raphe magnus nucleus, where monoaminergic neurons were also detected. In addition to the previously reported enkephalinergic cells, we found many methionine-enkephalin-Arg6-Gly7-Leu8 containing neurons; the rostral and caudal linear nucleus of raphe, the median raphe nucleus, entire length of the raphe magnus nucleus, the medial longitudinal fasciculus, the cuneate nucleus, the external cuneate nucleus, the gracile nucleus, and the area postrema. The wide distribution of this octapeptide-like immunoreactivity reflected neurons expressing the preproenkephalin A gene distributed more widely than previously reported and that innervated many regions.     

The nigral projection to predorsal bundle cells in the superior colliculus of the rat.

Predorsal bundle cells give rise to the major efferent pathway from the superior colliculus to the premotor centers of the brainstem and spinal cord responsible for initiating orienting movements. The activity of predorsal bundle cells is profoundly influenced by an inhibitory pathway from substantia nigra pars reticulata that uses gamma aminobutyric acid (GABA) as a neurotransmitter. The present study examines the morphological basis for this influence of substantia nigra on predorsal bundle cells in the rat. In the first experiments, the laminar distributions of the nigrotectal tract terminals and the predorsal bundle cells were compared. The predorsal bundle cells were labeled by the retrograde axonal transport of horseradish peroxidase from either the decussation of the predorsal bundle or the cervical spinal cord, while the terminations of the pathway from substantia nigra pars reticulata were labeled by anterograde axonal transport from the substantia nigra. Either horseradish peroxidase, wheat germ agglutinin conjugated to horseradish peroxidase, or Phaseolus vulgaris leucoagglutinin were used as anterograde tracers. The results showed that the distributions of both the predorsal bundle cells and the nigrotectal terminals are restricted almost entirely to the intermediate grey layer and that they overlap extensively. Predorsal bundle cells varied in size. Within the areas of maximum overlap, the majority, regardless of size, was closely apposed by nigrotectal terminals. In a second series of experiments, the synaptic contacts between nigrotectal terminals and the tectospinal component of the predorsal bundle were examined in tissue in which both the terminals and the tectospinal cells were labeled for electron microscopy. In the final experiments, the distribution and fine structure of the nigrotectal terminals were compared to those of terminals that had been labeled immunocytochemically with an antibody to glutamic acid decarboxylase, the synthesizing enzyme for GABA. The results showed that nigrotectal terminals contain large numbers of mitochondria and pleomorphic vesicles, and form synaptic contacts with the somas and proximal dendrites of tectospinal cells. These synapses have modest postsynaptic densities. In both their distribution and fine structure, these terminations resemble the glutamic acid decarboxylase immunoreactive terminals that contact tectospinal cells. Taken together, these results support the view that the nigrotectal tract is an important source of GABAergic input to most, if not all, predorsal bundle cells.     

高血压大鼠中脑导水管周围灰质内nNOS样阳性神经元的变化

目的：观察高血压大鼠中脑导水管周围灰质(PAG)内神经元型一氧化氮合酶(nNOS)样阳性神经元数量的变化。方法：用双肾双夹法建立高血压大鼠模型，ABC法显示PAG内nNOS样阳性神经元并进行定量分析。结果：nNOS样阳性神经元分布于PAG的背外侧区。PAG内nNOS样阳性神经元的数量、光密度在对照组各时期无明显变化；在高血压大鼠7d时的数量略减少，光密度略下降；而在30d、70d则数量、光密度逐渐减少，与对照组比较差异显著。结论：中脑PAG内nNOS样阳性神经元及阳性产物的减少可能与其对心血管功能活动、感觉信息传导的影响以及高血压的形成和发展有关。     

Does ageing have an effect on midbrain premotor nuclei for vertical eye movements?

Currently, there is debate in the clinical literature as to whether defects in vertical gaze are a consequence of normal ageing or a component of an underlying neurodegenerative disorder. Although pathological changes have been demonstrated in diseased subjects, no study to date has addressed the question of normal ageing effects. In this retrospective study, we examined 23 neurologically and pathologically normal subjects (age 18-91). Using an unbiased, frame-based sampling method, we quantified neuronal and glial cell densities in 10 young (<50) and 13 aged (>65) subjects in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), the key premotor substrate in the vertical gaze pathway. We found no statistically significant difference in neuronal density, glial cell density, or neuron-to-glial cell ratios between the young and the aged. We conclude, therefore, that neuronal loss, neuronal atrophy, or gliosis in the riMLF are not consequences of normal ageing.     

Changes in catecholamine concentrations in the hypothalamus and region of the midbrain raphe in male and female rats during postnatal development

To investigate possible sex differences in central catecholaminergic systems, the concentrations of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were measured by high-performance liquid chromatography with electrochemical detection in the hypothalamus-preoptic area (H-POA) and midbrain raphe (MR) region of male and female rats throughout postnatal development. Other than a small but significant sex difference in DA concentration in the MR at 36 h (higher in females), the results showed that there were no sex differences in the concentrations of DA or DOPAC at any age in either brain region. The developmental profiles of the concentrations of DA and DOPAC showed that DAergic systems in the H-POA are immature at birth, with concentrations increasing steadily until 80 days of age, but in the MR concentrations reach a maximum at 20 days of age; a situation which is perhaps a reflection of differing monoamine metabolism in the two areas.     

IL-1α及与IL-11、LIF和GDNF联合诱导胚鼠皮质、中脑神经干细胞向多巴胺神经元分化的比较

为比较皮质和中脑来源的神经干细胞(NSCs)定向分化为多巴胺神经元的情况,应用无血清和单克隆培养技术,分别从皮质和中脑组织中分离克隆、扩增NSCs,然后分成3组诱导分化:①对照组用10%胎牛血清诱导分化;②IL-1α组在10%胎牛血清的基础上加IL-1α诱导分化;③联合因子组在10%胎牛血清的基础上加IL-1α、IL-11、LIF及GDNF进行诱导分化。用酪氨酸羟化酶(TH)免疫组化染色检测多巴胺神经元。在100倍镜下随机取5个视野,计数每个视野中的TH阳性神经元数;并用图像分析软件处理TH阳性神经元的胞体面积和细胞周长;用STATA7.0统计软件进行统计处理。结果显示,皮质对照组中仅见极少的TH阳性神经元(0.25±0.163),中脑对照组中见少量TH阳性神经元(2±0.378);而皮质IL-1α组有较多的TH阳性神经元(15.5±0.866),中脑IL-1α组中的TH阳性神经元则为皮质IL-1α组的150%(22.875±1.517);皮质联合因子组中的TH阳性神经元数(25.75±0.940)与中脑联合因子组中的TH阳性神经元数(28.875±2.125)接近,无显著差异。胞体面积和细胞周长的结果显示出IL-1α组和联合因子组大于对照组、而联合因子组又优于IL-1α组的趋势。上述结果提示,中脑来源的NSCs本身具有一定的分化为多巴胺神经元的区域特异性,而皮质来源的NSCs在IL-1α、IL-11、LIF及GDNF等细胞因子的诱导下可改变其区域特异性而分化为较多较为成熟的多巴胺神经元。     

Ventral specification and perturbed boundary formation in the mouse midbrain in the absence of Hedgehog signaling.

Although Hedgehog (HH) signaling plays a critical role in patterning the ventral midbrain, its role in early midbrain specification is not known. We examined the midbrains of sonic hedgehog (Shh) and smoothened (Smo) mutant mice where HH signaling is respectively attenuated and eliminated. We show that some ventral (Evx1+) cell fates are specified in the Shh-/- mouse in a Ptc1- and Gli1-independent manner. HH-independent ventral midbrain induction was further confirmed by the presence of a Pax7-negative ventral midbrain territory in both Shh-/- and Smo-/- mice at and before embryonic day (E) 8.5. Midbrain signaling centers are severely disrupted in the Shh-/- mutant. Interestingly, dorsal markers are up-regulated (Wnt1, Gdf7, Pax7), down-regulated (Lfng), or otherwise altered (Zic1) in the Shh-/- midbrain. Together with the increased cell death seen specifically in Shh-/- dorsal midbrains (E8.5-E9), our results suggest specific regulation of dorsal patterning by SHH, rather than a simple deregulation due to its absence.     

P物质、亮氨酸脑啡肽、5-羟色胺样成分在新生儿中脑导水管周围灰质的分布

本文用PAP和ABC法对3例生后1—2天新生儿中脑导水管周围灰质(PAG)内P物质、亮氨酸脑啡肽、5-羟色胺样成分的分布进行了观察。发现P物质样阳性胞体主要位于PAG的中、尾段,分为位于腹外侧区的腹侧群和位于腹外侧区与背外侧区交界处的外侧群等两群。其阳性纤维和终末以背侧区为最密。亮氨酸脑啡肽样阳性胞体也出现于PAG中、尾段的各个区内,以腹外侧区数量为多,其阳性纤维及终末也以腹外侧区最密集。5-羟色胺样阳性胞体集中在PAG中、尾段的腹外侧区,其阳性纤维及终末主要分布于PAG的内侧区。本文还对此三种物质与镇痛机制的关系进行了讨论。     

Comparison of thermosensitivity in the preoptic/anterior hypothalamic area and the midbrain of the rabbit

Summary To characterize the role of the midbrain temperature-sensitive structure in thermoregulation, the relative importance of thermosensitivity in the hypothalamus and the midbrain was studied in terms of heat production and heat loss in the rabbit. It was found that altering the local temperature in the midbrain had no influence at all on heat loss from the ear surface and also on heat production, while cooling and warming of the preoptic/anterior hypothalamic area induced appropriate thermoregulatory responses.