Localization of immunoreactive alpha-bag-cell peptide in the central nervous system of Aplysia

The bag cells of the marine mollusc Aplysia are well-characterized neuroendocrine cells that initiate egg laying, but the natural stimulus triggering bag-cell activity has not been determined. As a first step toward identifying central neurons that might provide synaptic or neurohormonal input onto the bag-cell network, antibodies specific for alpha-bag-cell peptide (alpha-BCP) were generated. This peptide belongs to a small family of structurally related peptides that can elicit bag-cell activity in vitro. Antibody specificity was established by immunodot assay and preabsorption studies: immunocytochemical labeling was abolished in each ganglion when the antibodies were preincubated with either alpha-BCP-thyroglobulin conjugate or alpha-BCP-(1-8) but was not affected by preincubation with thyroglobulin or thyroglobulin-thyroglobulin conjugate. The antibodies specifically labeled the bag cells in the abdominal ganglion and ectopic bag cells in both the abdominal and right pleural ganglia. The ectopic bag cells were similar to conventional bag cells in size and morphology, but varied in number and location among preparations. In the cerebral ganglion, the antibodies labeled a bilaterally symmetrical pair of cell clusters, containing approximately ten cells each, on the dorsal surface of the ganglion. The cerebral cells were smaller than bag cells, were constant in location, and sent their processes into the neuropil rather than the connective tissue sheath. Immunoreactive processes were observed in the neuropils of the cerebral, pleural, and pedal ganglia and among the axons of the cerebropedal, cerebropleural, and pleurovisceral connectives. No immunoreactive cell bodies were observed in the buccal or pedal ganglia. Identical patterns of labeling were observed in Aplysia californica, A. brasiliana, and A. dactylomela. The distribution of immunoreactive cell bodies within the circumesophageal ganglia of all three species thus parallels the distribution of receptive sites for the in vitro induction of bag-cell activity by atrial gland peptide B, a peptide structurally related to alpha-BCP. These observations suggest that the immunoreactive cells identified in these studies, or a subset of them, may be involved in the physiological induction of bag-cell activity. Since low doses of alpha-BCP have additional inhibitory actions on the bag cells, however, it is possible that the identified cells could play a more complex role in the regulation of bag-cell activity.     

Immunocytochemical localization of a methionine-enkephalin-resembling neuropeptide in the central nervous system of the american cockroach,Periplaneta americana L

Using the peroxidase antiperoxidase immunocytochemical method, we were able to demonstrate within the brain and retrocerebral complex of Periplaneta americana several neuronal structures which were very specifically stained with an anti-methionine-enkephalin antiserum. From the precise localization of this immunoreactive material some speculations about its possible functions could be derived, such as a neurotransmitter- or neuromodulatorlike function and/or a neurohormonal role. These data present new evidence for the recently developed concept that opiate peptides, identical or related to those found in higher species, occur also in invertebrates.     

Sequence of pedal peptide: a novel neuropeptide from the central nervous system of Aplysia

We report the identification of a novel neuropeptide from Aplysia nervous tissue. The peptide was termed Pedal peptide (Pep) because it was predominantly synthesized in the pedal ganglia. Pep was purified and sequenced from pooled extracts of pedal ganglia. The following sequence was proposed: Pro-Leu-Asp-Ser-Val-Tyr-Gly-Thr-His-Gly-Met-Ser-Gly-Phe-Ala. Enzymatic hydrolysis procedures indicated that Pep had a free carboxyl terminal. A peptide with the proposed sequence was synthesized and compared with the native peptide. Chromatographic properties of the 2 peptides under 3 different conditioned were compared and found to be identical. Electrophysiological responses to the 2 peptides were compared on an identified neuron in the abdominal ganglia and found to be qualitatively and quantitatively very similar. Both peptides produced net inward currents that were associated with a decrease in membrane conductance. The results from these 2 procedures confirmed that the proposed Pep sequence was correct. Quantitative measurements of the incorporation of 35S-methionine into Pep suggest that cell bodies that synthesize Pep were present predominantly in the pedal ganglia but should also be found in other central ganglia as well. Pep-like immunoreactive neurons are found predominantly in the pedal ganglia and less frequently in the other ganglia (Pearson and Lloyd, 1989). Quantitatively, Pep constitutes one of the predominant peptides in the nervous system of Aplysia. Pep does not appear to be a member of any other previously identified invertebrate or vertebrate peptide family.     

Immunolocalization of cathepsin D in the human central nervous system and central nervous system neoplasms

The cellular distribution of the lysosomal proteinase cathepsin D was studied in a series of 76 neoplasms and 18 non-neoplastic tissues from the human central nervous system, using a well-characterized polyclonal antibody in a peroxidase-antiperoxidase technique. In the normal and developing brain, cathepsin D is confined to neurons and choroid plexus epithelium. Strong granular cytoplasmic staining was present in neuronal and choroid plexus neoplasms, and in reactive macrophages. A large variety of other neoplasms also exhibited positive cytoplasmic staining, albeit usually of a weaker diffuse type. Cathepsin D cannot be considered a specific marker for neuronal or choroid plexus neoplasms, but the antiserum used in this study may be of value in antibody panels for the investigation of these tumours. Its localization may also be of value in embryological studies, particularly in the cerebellum, and in investigations of steroid hormone receptor-associated proteins in meningiomas and Schwannomas.     

N-Acetylserotonin in the central nervous system

1. N-acetylserotonin has been identified by immunohistochemistry in specific brain areas separate from melatonin and serotonin. N-acetylserotonin is widely distributed within the brain stem, cerebellum and hippocampus and in the brain stem it is contained within reticular formation nuclei and motor nuclei. Like serotonin, N-acetylserotonin appears to be derived from tryptophan as tryptophan hydroxylase inhibition leads to a lowering in innunoreactive N-acetylserotonin in brain and blood. Beta adrenergic drugs influence N-acetylserotonin neurons with beta adrenergic agonists causing a rise in immunoreactive N-acetylserotonin. The presence of N-acetylserotonin in brain has been confirmed by gas chromatography, mass spectrometry and radioimmunoassay.

2. At this point little is known of the possible role of N-acetylserotonin in the brain. In the hippocampus N-acetylserotonin is present in granule cells and its appearance parallels the appearance of those cells. High affinity binding of tritiated N-acetylserotonin is found in brain and in various brain areas and this radioligand appears to label serotonergic receptors. Preliminary iontophoretic studies performed on hippocampal slices indicate an inhibitory action of N-acetylserotonin on glutamate induced firing of pyramidal cells.

3. Taken together these findings suggest that N-acetylserotonin may have a role in the central nervous system distinct from that of being a precursor for melatonin. If this hypothesis is correct it would suggest that indoleamines have certain similarities to catecholamines. Thus for the catecholamines, dopamine, norepinephrine and epinephrine form a synthetic sequence and yet have independent roles as neurotransmitters and/or hormones. The three indoleamines serotonin, N-acetylserotonin and melatonin also form a synthetic sequence and these three substances may also have independent roles as neurotransmitters and/or hormones.     

Expression of trk receptors in the developing and adult human central and peripheral nervous system

A family of tyrosine receptor kinases known collectively as trk receptors plays an essential role in signal transduction mediated by nerve growth factor and related neurotrophins. To localize the major trk receptors (trkA, B and C) in the developing and adult central (CNS) and peripheral (PNS) nervous system, we generated monoclonal antibodies (MAbs) to extracellular (MAbs E7, E13, E16, E21, E29) and intracellular (MAb I2) domains of human trkA fused to glutathione S-transferase. Several MAbs (E7, E13, E16) recognized glycosylated trkA (gp 140^trk and gp110^trk) in Western blots, one MAb (E7) recognized non-glycosylated (p80^trk) and glycosylated trkA in immunoprecipitation assays, and two MAbs (E13, E29) detected trkA on the cell surface of NIH3T3 cells transfected with a trkA cDNA. Although generated to trkA fusion proteins, this panel of MAbs also recognized trkB and trkC in flow cytometric studies of NIH3T3 cells transfected with trkB or trkC cDNAs. Thus, we used these pan-trk MAbs to probe selected regions of the CNS and PNS including the hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and dorsal root ganglion (DRG) to localize trkA, B, and C receptors in the developing and adult human nervous system. These studies showed that trk receptors are expressed primarily by neurons and are detectable very early in the developing hippocampus, cerebellum, spinal cord, and DRG. Although the distribution and intensity of trk immunoreactivity changed with the progressive maturation of the CNS and PNS, immunoreactive trk receptors were detected in neurons of the adult human hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and DRG. This first study of trk receptor proteins in the developing and adult human CNS and PNS documents the expression of these receptors in subsets of neurons throughout the developing and adult nervous system. Thus, although the expression of trk receptor proteins is developmentally regulated, the constitutive expression of these neurotrophin receptors by neurons in many regions of the adult human CNS and PNS implies that mature trk receptor-bearing neurons retain the ability to respond to neurotrophins long after terminal neuronal differentiation is complete. © 1995 Wiley-Liss, Inc.     

Ret expression in the central nervous system

The ret proto-oncogene product (Ret) has been shown to be one of the glial cell line-derived neurotrophic factor (GDNF) receptors in dopaminergic, norepinephric and motor neurons. We immunohistochemically examined the expression of Ret in the human central nervous system (CNS). The distribution of Ret was generally identical to that of myclin as stained using the Klüver-Barrera method. We further investigated the expression of Ret in human fetal brains (19, 29 and 39 weeks gestation) and various brain tumors. The Ret positivity was observed to be associated with the myelin sheath of the cerebral white matter in 29-and 39-week-old fetal brains. Ret is known to be expressed in neural crest-derived cells. We could immunohistochemically confirm the Ret expression in the pheochromocytomas and neuroblastomas of retroperitoneal space. As for the brain tumors, no Ret expression was observed in glioblastomas, oligodendrogliomas, and schwannomas examined, although the glial cells surrounding the tumor and the pre-existing myelin sheath revealed positivity for Ret. In the CNS, Ret expression appears to be closely associated with the myelin sheath; therefore, Ret immunostaining may be useful in ascertaining the demyelinating lesions in the CNS.     

The amyloid precursor protein gene: a neuropeptide gene with diverse functions in the central nervous system

The amyloid precursor protein (APP) is a member of a family of proteins found in the central nervous system with a fundamental role in the pathogenesis of Alzheimer's disease. This review describes the experimental evidence that has provided functional insights into this protein and emphasizes the importance of APP in many neurobiological processes.     

Immunohistochemical and gene rearrangement studies of central nervous system lymphomatoid granulomatosis

Lymphomatoid granulomatosis (LYG) is a rare multisystem disorder with characteristic angiocentric lymphoproliferative features, most frequently involving the lung, skin, and rarely the CNS. LYG has been classified into three subtypes based on the relative proportions of atypical and inflammatory infiltrating cells. Most systemic LYGs have been shown to be EBV‐associated, T‐cell rich, B‐cell proliferative disorders. Here, we present four cases of LYG arising from the CNS and have analyzed them by immunohistochemistry to assess the phenotype of the infiltrate, and by PCR‐SSCP (single‐strand conformation polymorphism) analysis for immunoglobulin heavy chain (IgH) and T‐cell receptor (TcR) γ gene rearrangements. Three cases revealed perivascular infiltration of T‐cell dominant lymphoid cells, two cases showed monoclonal TcRγ gene rearrangement, while the remaining case had a B‐cell immunophenotype and monoclonal IgH gene rearrangement with EBV genome expression. This is the first report of a gene rearrangement study on CNS‐LYG. We confirm that some cases of CNS‐LYG are derived from T‐cell monoclonal lymphoproliferative disease, although this disease should be classified as a borderline malignancy and should be separated from overt malignant lymphoma of CNS.     

Glutamine synthetase is a glial-specific marker in the olfactory regions of the lobster (Panulirus argus) nervous system

Glutamine synthetase (GS) has been qualified as a very specific marker of astroglial-type neuroglia in vertebrate neural tissues. In this paper we have begun to examine the possibility that glial localization of GS could be a ubiquitous characteristic of complex nervous systems. To this end we have used immunohistochemistry to localize GS-like immunoreactivity in the olfactory regions of the complex nervous system of the arthropod, the spiny lobster Panulirus argus. We describe a novel method for affinity isolation of antibodies from crude serum. Using this approach we purified GS-specific antibodies to chick retina GS and used these to analyze the lobster brain and the primary olfactory organ. Western blots showed that the lobster brain contains an immunoreactive peptide with nearly the same molecular mass as that of chick retina GS. Northern blot analyses of mRNA and enzymatic activity assays also confirm that the lobster brain produces GS. Immunohistochemical staining of sectioned lobster olfactory lobes and sensory sensilla showed strong reactivity in specific cells. Comparison of the GS immunostaining pattern with that for FMRFamide, a well characterized marker of neurons in invertebrate neural tissues, it became clear that GS is indeed glial-specific in lobster neural tissues as it is in vertebrates. These results suggest that the compartmentalization of GS in non-neuronal cells is either an early step in neural evolution or is an obligate and fundamental characteristic of complex neural systems composed of both neurons and neuroglia. GLIA 20:275–283, 1997. © 1997 Wiley-Liss, Inc.     

Neurotensin: central nervous system effects of a neuropeptide

Neurotensin is a tridecapeptide heterogeneously distributed in the central nervous system and the gastrointestinal tract of mammals. When administered into the central nervous system, the peptide produces hypothermia, analgesia, diminished locomotor activity and muscle relaxation. In addition neurotensin antagonizes certain amphetamine-induced behaviours and these observations taken together with data derived from experiments utilizing pharmacological blocking agents and neurotoxins, support the hypothesis that the peptide interacts with brain dopamine systems. Many of the effects of centrally administered neurotensin are antagonized by administration of the tripeptide, thyrotropin-releasing hormone. The effects of exogenously administered neurotensin suggest that endogenous neurotensin may participate in the regulation of a variety of physiological and behavioural processes.     

CXCR4/CXCL12在原发中枢神经系统淋巴瘤中的表达及其意义

目的 探讨趋化因子受体CXCR4 及其配体CXCL12 在原发中枢神经系统淋巴瘤中的表达水平,分析它们在原发中枢神经系统淋巴瘤的发生、发展过程中的可能作用.方法 采用免疫组化EnVision 二步法检测CXCR4 及CXCL12 在5 例原发中枢神经系统淋巴瘤、10 例正常脑组织细胞中的表达.采用半定量RT-PCR 检测CXCR4 和CXCL12 在5 例原发中枢神经系统淋巴瘤以及正常脑组织中的表达情况.结果 免疫组化EnVision二步法:CXCR4 在肿瘤标本中阳性表达率为100% (5/5),在正常脑组织标本中阳性表达率为0% (0/10);CXCL12 在肿瘤标本中阳性表达率为100% (5/5),在正常脑组织标本中阳性表达率为100% (10/10).半定量RT-PCR法检测标本中的CXCR4、CXCL12 显示:在肿瘤标本中全部检出,而在正常脑组织标本中仅检出CXCL12 的表达.结论 CXCR4/CXCL12 信号通路在原发中枢神经系统淋巴瘤的发生、发展过程中起作用.     

Localization of GABA-like immunoreactivity in the central nervous system of Aplysia californica.

Gamma-aminobutyric acid (GABA) is present in the central nervous system of Aplysia californica (Gastropoda, Opisthobranchia) where its role as a neurotransmitter is supported by pharmacological, biochemical, and anatomical investigations. In this study, the distribution of GABA-immunoreactive (GABAi) neurons and fiber systems in Aplysia was examined by using wholemount immunohistochemistry and nerve backfill methods. GABAi neurons were located in the buccal, cerebral, and pedal ganglia. Major commissural fiber systems were present in each of these ganglia, whereas more limited fiber systems were observed in the ganglionic connectives. Some of the interganglionic fibers were found to originate from two unpaired GABAi neurons, one in the buccal ganglion and one in the right pedal ganglion, each of which exhibited bilateral projections. No GABAi fibers were found in the nerves that innervate peripheral sensory, motor, or visceral organs. Although GABAi cells were not observed in the pleural or abdominal ganglia, these ganglia did receive limited projections of GABAi fibers originating from neurons in the pedal ganglia. The distribution of GABAi neurons suggests that this transmitter system may be primarily involved in coordinating certain bilateral central pattern generator (CPG) systems related to feeding and locomotion. In addition, the presence of specific interganglionic GABAi projections also suggests a role in the regulation or coordination of circuits that produce components of complex behaviors.     

Catecholamine-containing cells in the central nervous system and periphery of Aplysia californica.

Previous studies have suggested the presence of numerous catecholamine-containing cells in both the central ganglia and peripheral tissues of Aplysia, but they often offered conflicting or incomplete accounts of numbers, locations, and morphologies. The current study combines aldehyde-induced histofluorescence and tyrosine hydroxylase-like immunoreactivity together with confocal microscopy to provide details of these cells. Approximately 35-50 neurones in the cerebral ganglia, 4-8 neurones in the pedal ganglia, 5 neurones in the buccal ganglia, and numerous small fibres in various nerve trunks exhibited both immunoreactivity and aldehyde-induced fluorescence. Approximately 20 cells in the pedal ganglia and 4 cells in the buccal ganglia exhibited only immunoreactivity whereas 15-20 neurons in the cerebral ganglia exhibited only aldehyde-induced fluorescence. No somata in the pleural or abdominal ganglia exhibited aldehyde-induced fluorescence or immunoreactivity. Both aldehyde-induced histofluorescence and immunoreactivity also labelled what appeared to be two classes of catecholamine-containing cells in the gill, siphon, oesophagus, rhinophore, tentacle, and reproductive organs. The more numerous, but smaller cells had subepithelial somata and processes penetrating the overlying body wall, thus suggesting a sensory function. Another class of neurones had larger somata, often located more deeply within the tissue, and occasionally appeared to be multipolar. Processes from these various peripheral cells appeared to comprise the major component of afferent fibres and to form an extensive peripheral plexus, often associated with various muscles. The morphologies of the peripheral cells thus suggest involvement in both local and centrally mediated reflexes and responses, but additional studies must test such hypothesised functions and determine the sensory modalities that the cells mediate.     

Expression of the gene for preproatriopeptin in the central nervous system of the rat

Atriopeptin (AP) is a peptide hormone synthesized and secreted by the atria of the heart that participates in the regulation of fluid and electrolyte balance. AP-like materials have been detected immunologically in neurons in the central nervous system of the rat. In this study, we have used a solution hybridization-nuclease protection assay to determine whether the brain of the rat contains RNA coding preproatriopeptin, the atrial biosynthetic precursor of AP, and to study the regional distribution of preproatriopeptin mRNA in the brain. We have found that the brain contains mRNA identical to the atrial messenger RNA for preproatriopeptin. AP mRNA is differentially distributed in the brain; the highest concentration was found in the hypothalamus, followed by the cortex and septum, hippocampus, midbrain, spinal cord, olfactory bulb, striatum, and pons and medulla. Very low levels were found in the cerebellum, while no detectable AP mRNA was observed in retina, anterior pituitary, or rat liver. The presence of AP mRNA in the brain demonstrates that neurons have the capacity to synthesize preproatriopeptin identical to that produced in the heart. Bioactive peptides produced from this precursor may be endogenous central neuromodulators as well as a circulating hormone.     

Detection of neuropeptide release in the central nervous system with antibody microprobes

Antibody microprobes are glass micropipettes bearing a uniform layer of immobilized antibodies on their outer surfaces. When a microprobe is placed in the central nervous system, localized release of a ligand for the particular antibody produces binding at a localized area of the microprobe. This is detected on microprobe autoradiographs as deficits in the binding of a radiolabelled form of the ligand in which probes are incubated after withdrawal from the brain or spinal cord. An image analysis system scans autoradiographs quantitatively. Experiments are best done under near sterile conditions as peptides and proteases occur in inflammatory exudates.     

Apoptosis in metastatic carcinoma of the central nervous system

High apoptotic indices have been described in pseud-opalisading areas of glioblastoma multiforme (astrocytoma grade 4). In order to explore further the role of apoptosis in regulating the proliferation in central nervous system (CNS) tumors, we used TdT-mediated dUTP-nick endlabeling (TUNEL) methods to compare the frequency and distribution of apoptotic cells in 32 cases of metastatic carcinoma and 54 cases of primary diffuse astrocytomas. Frequencies of apoptotic cells and Bcl-2 positive cells in metastatic carcinoma were low compared with those observed in high-grade diffuse astrocytomas and did not correlate with the expression of the p53 protein. These findings suggest that apoptosis does not have a major role in regulating proliferation in metastatic carcinoma of the CNS.     

Localization and quantification of 5-hydroxytryptophan and serotonin in the central nervous systems of Tritonia and Aplysia

Serotonin (5-hydroxytryptamine, 5-HT) plays a central role in several behaviors in marine molluscs and other species. In an effort to better understand the regulation of 5-HT synthesis, we used high performance liquid chromatography (HPLC) with electrochemical detection and immunohistochemistry to measure and map the distribution of the immediate precursor of 5-HT, 5-hydroxytryptophan (5-HTP), in two model opisthobranch molluscs, the nudibranch Tritonia diomedea and the anaspid Aplysia californica. HPLC measurements showed that 5-HTP is present at approximately the same level as the 5-HT metabolite, 5-hydroxyindolacetic acid (5-HIAA) but is more than 100 times lower in concentration than either 5-HT or dopamine in the same tissue. Specific 5-HTP immunoreactivity was colocalized with serotonin in both species. The overall intensity of 5-HTP immunoreactivity in individual ganglia agreed with HPLC measurements for those ganglia. The intensity of 5-HTP immunolabeling varied between cell types and was correlated with the intensity of 5-HT immunolabeling. In particular, differences in staining intensity were consistently seen among the three dorsal swim interneurons of the Tritonia swim central pattern generator circuit. Some nonserotonergic neurons also displayed low levels of 5-HTP immunolabeling that were above background levels. Together, these results support the notion that production of 5-HTP is a rate-limiting step in serotonin synthesis and suggest that there may be additional regulation that allows 5-HTP to accumulate to varying levels.     

Immunocytological localization of pedal peptide in the central nervous system and periphery of Aplysia

Immunocytology using antisera raised to conjugated pedal peptide (Pep) was used to localize the peptide in the CNS and periphery of Aplysia. A total of over 200 neurons in the CNS exhibited Pep-like immunoreactivity. As expected from results presented in the previous paper, immunoreactive neurons were heavily concentrated in the pedal ganglia, primarily in a broad ribbon comprised of about 60 large contiguous neurons on the dorsal side of each ganglion. Smaller and less numerous immunoreactive neurons were found in the other ganglia. A number of neurons primarily located in the abdominal ganglia had dense networks of immunoreactive varicose fibers surrounding their cell bodies. Many immunoreactive axons were observed in peripheral nerves, particularly those nerves leaving the pedal ganglia. Analyses of sections of body wall indicated that Pep-like immunoreactivity was localized to a series of varicose axons that appeared to be associated with vascular spaces, muscle fibers, and other large cells. These axons likely arise from pedal ganglion nerves that were shown to transport large amounts of 35S-labeled Pep to the periphery. These results suggest that Pep is a transmitter-like neuropeptide that is likely to have a number of important physiological actions in Aplysia.