Anatomical localization of corticotropin-releasing activity in the human brain

Corticotropin-releasing activity (CRa) and arginine-vasopressin (AVP) content were measured in seven human hypothalami. The hypothalami were obtained from routine autopsy of patients suffering from no obvious neuroendocrinological abnormality. Twelve distinct hypothalamic areas were dissected in the frozen state and extracted in aqueous solution. CRa was measured by a bioassay measuring the aCTH released by rat pituitary cells in vitro, and vasopressin by direct radioimmunoassay. CRa was detectable in almost every area with the highest values in the supraoptic, paraventricular and infundibular (arcuate) areas. Vasopressin concentrations were maximum in the supraoptic nucleus, followed by the paraventricular and infundibular nuclei. We conclude that: hypothalami obtained from routine autopsy at a general hospital can be used for consistent CRa and vasopressin assay. Vasopressin and CRa are similarly distributed in man and in the rat. In both species, high CRa, which is not explained by AVP, is found in the paraventricular nucleus. The infundibular (arcuate) nucleus seems to display non AVP-dependent CRa much greater in the human than in the rat.     

心脏副交感节前神经元的研究进展

近年来,应用逆行荧光标记技术和膜片钳技术,对心脏副交感节前神经元(PCPNs)的研究取得很大进展。PCPNs不具有自主发放特性,其活动完全依赖于其突触前支配。PCPNs主要受胆碱能、兴奋性氨基酸能、GABA能及甘氨酸能支配;这些递质传递之间除相互作用外,还受多种神经肽及药物的影响。胆碱能递质对GABA能及甘氨酸能突触前支配的易化作用,参与生理性呼吸性窦性心律不齐的产生,其异常可能与多种心血管疾病发生有关。     

Swallowing reflex and brain stem neurons activated by superior laryngeal nerve stimulation in the mouse

The purpose of the present study was to identify vagal subnuclei that participate in reflex swallowing in response to electrical stimulation of the left superior laryngeal nerve (SLN). SLN stimulation at 10 Hz evoked primary peristalsis, including oropharyngeal and esophageal peristalsis, and LES relaxation. It also induced c-fos expression in interneurons in the interstitial (SolI), intermediate (SolIM), central (SolCe), dorsomedial (SolDM) and commissural (SolC) solitary subnuclei. Neurons in parvicellular reticular nucleus (PCRt) and area postrema (AP) and motoneurons in the semicompact (NAsc), loose (NAl), and compact (NAc) formations of the nucleus ambiguus and both rostral (DMVr) and caudal (DMVc) parts of the dorsal motor nucleus of vagus were also activated. The activated neurons represent all neurons concerned with afferent SLN-mediated reflexes, including the swallowing-related neurons. SLN stimulation at 5 Hz elicited oropharyngeal and LES but not esophageal responses and evoked c-fos expression in neurons in SolI, SolIM, SolDM, PCRt, AP, NAsc, NAl, and DMVc but not in SolCe, NAc, or DMVr. These data are consistent with the role of SolI, SolIM, SolDM, NAsc, NAl, and DMVc circuit in oropharyngeal peristalsis and LES relaxation and SolCe, NAc, DMVc, and DMVr in esophageal peristalsis and LES responses.     

Horseradish peroxidase localization of sympathetic postganglionic and parasympathetic preganglionic neurons innervating the monkey heart

The localization of the sympathetic postganglionic and parasympathetic preganglionic neurons innervating the monkey heart were investigated through retrograde axonal transport with horseradish peroxidase (HRP). HRP (4 mg or 30 mg) was injected into the subepicardial and myocardial layers in four different cardiac regions. The animals were euthanized 84-96 hours later and fixed by paraformaldehyde perfusion via the left ventricle. The brain stem and the paravertebral sympathetic ganglia from the superior cervical, middle cervical, and stellate ganglia down to the T9 ganglia were removed and processed for HRP identification. Following injection of HRP into the apex of the heart, the sinoatrial nodal region, or the right ventricle, HRP-labeled sympathetic neurons were found exclusively in the right superior cervical ganglion (64.8%) or in the left superior cervical ganglion (35%). Fewer labeled cells were found in the right stellate ganglia. After HRP injection into the left ventricle, labeled sympathetic cells were found chiefly in the left superior cervical ganglion (51%) or in the right superior cervical ganglion (38.6%); a few labeled cells were seen in the stellate ganglion bilaterally and in the left middle cervical ganglion. Also, in response to administration of HRP into the anterior part of the apex, anterior middle part of the right ventricle, posterior upper part of the left ventricle, or sinoatrial nodal region, HRP-labeled parasympathetic neurons were found in the nucleus ambiguus on both the right (74.8%) and left (25.2%) sides. No HRP-labeled cells were found in the dorsal motor nucleus of the vagus on either side.     

Region-specific generation of functional neurons from naive embryonic stem cells in adult brain

Embryonic stem (ES) cells are multipotent progenitors with unlimited developmental potential, and in vitro differentiated ES cell-derived neuronal progenitors can develop into functional neurons when transplanted in the central nervous system. As the capacity of naive primary ES cells to integrate in the adult brain and the role of host neural tissue therein are yet largely unknown, we grafted low densities of undifferentiated mouse ES (mES) cells in adult mouse brain regions associated with neurodegenerative disorders; and we demonstrate that ES cell-derived neurons undergo gradual integration in recipient tissue and acquire morphological and electrophysiological properties indistinguishable from those of host neurons. Only some brain areas permitted survival of mES-derived neural progenitors and formed instructive environments for neuronal differentiation and functional integration of naive mES cells. Hence, region-specific presence of microenvironmental cues and their pivotal involvement in controlling ES cell integration in adult brain stress the importance of recipient tissue characteristics in formulating cell replacement strategies for neurodegenerative disorders.     

The histological localization of DNA in rabbit medullary neurons

The nuclei of unfixed isolated rabbit neurons cleared on incubation with DNAse (10 mg/ml), but not RNAse (10 mg/ml). The nuclei stained for DNA with eight chromosomal or nuclear stains more intensely than the cytoplasm, and less intensely after treatment with DNAse (10 mg/ml). On the other hand, when the whole tissue was embedded and sectioned, DNA did not appear to be stained in the nucleus; the nucleolus and the cytoplasm were more heavily stained than the nucleoplasm. Possible explanations for this apparent anomaly are considered. It was concluded that DNA diffused out of the nucleus during embedding and sectioning, and that the colouration of the nucleolus and cytoplasm with the eight staining systems used was due to other nucleotides present.     

Effects of lingual nerve section on morphometric characteristics of reticular nucleus neurons in the kitten brain stem

Computerized morphometric techniques were used to investigate each of 23 parameters in three types of brain stem reticular nucleus neurons in Golgi-stained frontal slices from the brain of 30-day-old kittens after uni- and bilateral lingual nerve section 5–7 days after birth. Particular statistically significant differences in some parameters were discovered in all types of cell. Certain group-specific differences in parameters could be most frequently distinguished in each category: distribution of loose dendritic endings through the dendritic area in reticular neurons, length of dendritic segments in branching cells, and distribution of foci of dendritic arborization in giant multipolar neurons. Unilateral lingual nerve section results in quantitatively more marked deviation from the normal state. It was only under these circumstances, moreover, that differences in overall length of dendrites could be seen, which could indicate a difference in the surface area of the cell.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 23, No. 4, pp. 409–418, July–August, 1991.     

Immunofluorescence localization of corticoliberin neurons in the brain of pigeons

With immunofluorescence techniques using one anti-rat or two different anti-ovine CRF, the localization of corticotropin-releasing factor (CRF) producing neurons was characterized in frozen sections of pigeon brain. Colchicine was administered intraventricularly at various day hours. The CRF neurons were localized in the telencephalon: lobus parolfactorius, nucleus (n.) accumbens, anterior commissure; in the diencephalon: n. dorso-medialis and lateralis thalami and in different structures of the hypothalamus: n. praeopticus periventricularis and medialis, paraventricularis, supraopticus medialis, lateralis, ectomamillaris and in the stratum cellulare externum. Concerning the hypothalamic localizations, results are discussed in the light of physiological studies on corticotropic regulations in pigeons. Additional populations of CRF neurons were also located in various brainstem areas substantia grisea centralis, locus caeruleus, n. tegmenti dorsalis, sensorius principalis nervi trigemini, vestibularis latetalis, solitarius, nervi hypoglossi, in the dorsal area of the n. pontis lateralis and in the n. paramedianus paragiganto--cellularis, raphes, nervi facialis, subcaeruleus and the area ventralis. These particular localizations may lead to the assumption that CRF might be involved in nervous regulations other than those related to the corticotropic function.     

The problem of functional localization in the human brain

Functional imaging gives us increasingly detailed information about the location of brain activity. To use this information, we need a clear conception of the meaning of location data. Here, we review methods for reporting location in functional imaging and discuss the problems that arise from the great variability in brain anatomy between individuals. These problems cause uncertainty in localization, which limits the effective resolution of functional imaging, especially for brain areas involved in higher cognitive function.     

Ultrastructural localization of immunoglobulin G and complement C9 in the brain stem and spinal cord following peripheral nerve injury: an immunoelectron microscopic study

Summary The ultrastructural localization of immunoreactivity for immunoglobulin G (IgG), F(ab′)2 and complement C9 was examined with preembedding immunoelectron microscopy in the hypoglossal nucleus and gracile nucleus as well as in the L4 spinal cord dorsal horn 1 week following hypoglossal or sciatic nerve transection, respectively. Only a few scattered immunoreactive profiles were observed on the unoperated side. On the operated side, IgG and F(ab′)2 immunoreactivity was present in the membranes of all reactive microglial cells observed. In addition, the cell membrane of some hypoglossal motoneurons showed IgG immunoreactivity. Complement C9 immunoreactivity was present in the cytoplasm of all reactive microglial cells examined. In addition, there was diffuse C9 immunoreactivity in motoneuron perikarya ipsilateral to nerve injury as well as in cell membranes in the neuropil, some of which could be identified as neuronal. Our interpretation of these findings is (1) that peripheral nerve injury results in binding of IgG to reactive microglia, as well as to some axotomized neurons, and (2) that C9 is synthesized by reactive microglia in response to axon injury and is also associated with axotomized motoneurons. These findings suggest that IgG and complement C9 are involved in microglia-neuron interactions after peripheral nerve injury.     

Intranuclear localization of iron in neurons of mammalian brain

Using Perls’ histochemical method, iron was revealed in the brain structures of human and rat. Iron accumulation was observed in perivascular areas and neuropil of substantia nigra as well as in white matter of cerebellum. After diaminobenzidine enhancement of histochemical reaction, the iron was revealed in nucleoli of many neurons, which is described for the first time in animal cells.     

PACAP is expressed in sympathoexcitatory bulbospinal C1 neurons of the brain stem and increases sympathetic nerve activity in vivo

Pituitary adenylate cyclase-activating polypeptide (PACAP) is an excitatory neuropeptide present in the rat brain stem. The extent of its localization within catecholaminergic groups and bulbospinal sympathoexcitatory neurons is not established. Using immunohistochemistry and in situ hybridization, we determined the extent of any colocalization with catecholaminergic and/or bulbospinal projections from the brain stem was determined. PACAP mRNA was found in tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the C1-C3 cell groups. In the rostral ventrolateral medulla (RVLM), PACAP mRNA was found in 84% of the TH-ir neurons and 82% of bulbospinal TH-ir neurons. The functional significance of these PACAP mRNA positive bulbospinal neurons was tested by intrathecal administration of PACAP-38 in anaesthetized rats. Splanchnic sympathetic nerve activity doubled (110%) and heart rate rose significantly (19%), although blood pressure was unaffected. In addition, as previously reported, PACAP was found in the A1 cell group but not in the A5 cell group or in the locus coeruleus. The RVLM is the primary site responsible for the tonic and reflex control of blood pressure through the activity of bulbospinal presympathetic neurons, the majority of which contain TH. The results indicate 1) that pontomedullary neurons containing both TH and PACAP that project to the intermediolateral cell column originate from C1-C3 and not A5, and 2) intrathecal PACAP-38 causes a prolonged, sympathoexcitatory effect.