Catecholaminergic Markers Research Articles

CRISPR/Cas9-based QF2 knock-in at the tyrosine hydroxylase (th) locus reveals novel th-expressing neuron populations in the zebrafish mid- and hindbrain.

Catecholaminergic neuron clusters are among the most conserved neuromodulatory systems in vertebrates, yet some clusters show significant evolutionary dynamics. Because of their disease relevance, special attention has been paid to mammalian midbrain dopaminergic systems, which have important functions in motor control, reward, motivation, and cognitive function. In contrast, midbrain dopaminergic neurons in teleosts were thought to be lost secondarily. Here, we generated a CRISPR/Cas9-based knock-in transgene at the th locus, which allows the expression of the Q-system transcription factor QF2 linked to the Tyrosine hydroxylase open reading frame by an E2A peptide. The QF2 knock-in allele still expresses Tyrosine hydroxylase in catecholaminergic neurons. Coexpression analysis of QF2 driven expression of QUAS fluorescent reporter transgenes and of th mRNA and Th protein revealed that essentially all reporter expressing cells also express Th/th. We also observed a small group of previously unidentified cells expressing the reporter gene in the midbrain and a larger group close to the midbrain-hindbrain boundary. However, we detected no expression of the catecholaminergic markers ddc, slc6a3, or dbh in these neurons, suggesting that they are not actively transmitting catecholamines. The identified neurons in the midbrain are located in a GABAergic territory. A coexpression analysis with anatomical markers revealed that Th-expressing neurons in the midbrain are located in the tegmentum and those close to the midbrain-hindbrain boundary are located in the hindbrain. Our data suggest that zebrafish may still have some evolutionary remnants of midbrain dopaminergic neurons.

A single cell transcriptomics map of paracrine networks in the intrinsic cardiac nervous system

SummaryWe developed a spatially-tracked single neuron transcriptomics map of an intrinsic cardiac ganglion, the right atrial ganglionic plexus (RAGP) that is a critical mediator of sinoatrial node (SAN) activity. This 3D representation of RAGP used neuronal tracing to extensively map the spatial distribution of the subset of neurons that project to the SAN. RNA-seq of laser capture microdissected neurons revealed a distinct composition of RAGP neurons compared to the central nervous system and a surprising finding that cholinergic and catecholaminergic markers are coexpressed, suggesting multipotential phenotypes that can drive neuroplasticity within RAGP. High-throughput qPCR of hundreds of laser capture microdissected single neurons confirmed these findings and revealed a high dimensionality of neuromodulatory factors that contribute to dynamic control of the heart. Neuropeptide-receptor coexpression analysis revealed a combinatorial paracrine neuromodulatory network within RAGP informing follow-on studies on the vagal control of RAGP to regulate cardiac function in health and disease.

SPARC: A Comprehensive Single Neuron Molecular Phenotype Map of the Right Atrial Ganglionated Plexus in the Pig Heart

As part of the NIH SPARC program efforts to study the intrinsic cardiac nervous system, we developed the first comprehensive molecular phenotyping data on the right atrial ganglionated plexus (RAGP) within the intrinsic cardiac nervous system of the pig. We collected hundreds of single neurons from the RAGP and assayed these for expression of a wide range of genes relevant to neuronal functions. The sinoatrial node (SAN) of 4 pigs were injected with FastBlue, a retrograde tracer, labeling neurons projecting to the SAN. The RAGP of those pigs were then collected and sectioned. Both SAN‐projecting and non‐SAN‐projecting single neurons in RAGP were collected through laser capture microdissection (LCM), allowing for spatial mapping of all collected samples. Over 400 single neurons were collected (n=4 animals) and each neuron was assayed for over 300 genes using high throughput microfluidic qPCR using BioMark. Neuronal phenotypes were distinguished by multivariate analysis showing patterns of network activity between multiple genes. Interestingly, these phenotypes show no spatial preferences within the RAGP. Our results revealed extensive combinatorial expression of neurotransmitters across the RAGP neuronal phenotypes. Additionally, there was a large overlap in expression profiles of SAN‐projecting and non‐SAN‐projecting neurons, without any single gene or module acting as a distinguishing marker between the connectionally labeled groups. Previous studies have focused on cholinergic and catecholaminergic processes, showing evidence for extensive protein expression of cholinergic markers in RAGP. Our findings are in stark contrast to these results and demonstrate high gene expression correlation between cholinergic and catecholaminergic markers such as tyrosine hydroxylase (Th) and choline acetyltransferase (ChAT) in single neurons. This finding suggests that cells are poised for a rapid shift in neurotransmitter signaling as well as the possibility for post transcriptional regulation of neuron phenotype plasticity. Our present findings significantly expand the list of neuromodulatory peptides and their receptors known to be expressed in RAGP. For example, neuropeptide Y and somatostatin showed distinct co‐expression patterns with their respective receptors with significant non‐overlapping expression of transmitters and cognate receptors across single neurons. Taken together, our results reveal a complex organization of neuronal networks within RAGP‐SAN complex that is not entirely governed by connectivity or spatial location, with combinatorial patterns of local paracrine networks with potential influence on cardiac function.Support or Funding InformationSupported by the NIH Common Fund SPARC Program award OT2 OD023848 and NIH NHLBI Multiscale Modeling award U01 HL133360.

TNF inhibits catecholamine production from induced sympathetic neuron-like cells in rheumatoid arthritis and osteoarthritis in vitro

Synovial adipose stem cells (sASC) can be differentiated into catecholamine-expressing sympathetic neuron-like cells to treat experimental arthritis. However, the pro-inflammatory tumor necrosis factor (TNF) is known to be toxic to catecholaminergic cells (see Parkinson disease), and this may prevent anti-inflammatory effects in inflamed tissue. We hypothesized that TNF exhibits inhibitory effects on human differentiated sympathetic tyrosine hydroxylase-positive (TH+) neuron-like cells. For the first time, iTH+ neuron-like sympathetic cells were generated from sACSs of rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissue. Compared to untreated controls in both OA and RA, TNF-treated iTH+ cells demonstrated a weaker staining of catecholaminergic markers in cell cultures of RA/OA patients, and the amount of produced noradrenaline was markedly lower. These effects were reversed by etanercept. Exposure of iTH+ cells to synovial fluid of RA patients showed similar inhibitory effects. In mixed synovial cells, significant effects of TNF on catecholamine release were observed only in OA. This study shows that TNF inhibits iTH+ synovial cells leading to the decrease of secreted noradrenaline. This might be a reason why discovered newly appearing TH+ cells in the synovium are not able to develop their possible full anti-inflammatory role in arthritis.

Fast neurogenesis from carotid body quiescent neuroblasts accelerates adaptation to hypoxia.

Unlike other neural peripheral organs, the adult carotid body (CB) has a remarkable structural plasticity, as it grows during acclimatization to hypoxia. The CB contains neural stem cells that can differentiate into oxygen-sensitive glomus cells. However, an extended view is that, unlike other catecholaminergic cells of the same lineage (sympathetic neurons or chromaffin cells), glomus cells can divide and thus contribute to CB hypertrophy. Here, we show that O2-sensitive mature glomus cells are post-mitotic. However, we describe an unexpected population of pre-differentiated, immature neuroblasts that express catecholaminergic markers and contain voltage-dependent ion channels, but are unresponsive to hypoxia. Neuroblasts are quiescent in normoxic conditions, but rapidly proliferate and differentiate into matureglomus cells during hypoxia. This unprecedented "fast neurogenesis" is stimulated by ATP and acetylcholine released from mature glomus cells. CB neuroblasts, which may have evolved to facilitate acclimatization to hypoxia, could contribute to the CB oversensitivity observed in highly prevalent human diseases.

Commentary on Chapters ‘Clinical and Developmental Aspects’ and ‘Stress Responses of the Adrenal Medulla’

The division of the contributions to this volume into Chromogranins, Ion Channels, Secretion Mechanisms, Clinical and Developmental Aspects, and Stress Responses of the Adrenal Medulla is somewhat arbitrary: there is clearly much overlap among these domains of chromaffin cell research. This commentary covers both Clinical/ Developmental, and Stress Responses together, mainly to emphasize this overlap, and the translational importance of these two aspects of the chromaffin cell as a stress transducer. Genetics, development and stress were three topics of particular clinical relevance that were developed in depth through contributions presented at the 15th International Symposium for Chromaffin Cell Biology. The genetics of the chromaffin cell in normal physiology and disease were highlighted by contributions focusing on markers of chromaffin cell origin relevant to cancer including pheochromocytoma, and on catecholaminergic markers for hypertension and other cardiovascular diseases. Colon, pancreas, prostate and lung outrank the adrenal medulla as organs of medical concern in human cancer. Although pheochromocytoma, or cancer of adrenomedullary origin is rare, it is an important subject of study for several reasons. First, it arises from a limited and distinct set of cell types, and therefore is an attractive model for etiology of proliferative disease. Second, pheochromocytoma can be either metastatic, malignant or benign, and therefore can be used to search for markers to make this clinically crucial diagnosis. Murthy et al. propose carboxypeptidase E (CPE), the enkephalin prohormone processing enzyme first characterized in bovine chromaffin granules in 1982 (Hook et al., Nature 295:341–342, 1982), as such a marker. Meta-analysis of microarray expression data sets in the Gene Expression Omnibus (GEO) allowed Murthy and colleagues to identify CPE as a transcript frequently represented in the transcriptomes of metastatic cancers of both endocrine and epithelial origin. Thus, cervical, colorectal, renal, and bone (Ewing sarcoma), astrocytic, and oligodendroglial tumors or cells express higher levels of CPE mRNA than their non-cancerous cells and tissues of origin: in fact most of the corresponding cells of origin do not have appreciable concentrations of CPE. Lung, pituitary and pheochromocytoma tissue (i.e. neuroendocrine tumors) express higher CPE levels than their tissues of origin. Most significantly, metastatic pheochromocytoma expresses significantly higher CPE mRNA than benign. Should CPE prove a reliable prognostic marker for malignancy in pheochromocytoma and other neuroendocrine cancers, and perhaps even in non-endocrine cancers, its potential for translation to standard clinical practice would be high. Thouennon and Anouar report on expression of neuropeptides in pheochromocytoma that may be involved in trophic, proliferative and angiogenic paracrine/autocrine actions contributing to tumor growth. A strong correlation between NPY and PACAP expression was documented in 25 pheochromocytomas, and between RDC1, the adrenomedullin receptor, and VEGF, with angiogenic activity. These authors review the evidence for concerted expression This is a commentary to articles doi:10.1007/s10571-010-9535-7 10.1007/s10571-010-9567-z, 10.1007/s10571-010-9571-3, 10.1007/s10571-010-9578-9, 10.1007/s10571-010-9575-z, 10.1007/s10571-010-9582-0, 10.1007/s10571-010-9583-z, 10.1007/s10571-010-9592-y, 10.1007/s10571-010-9593-x, 10.1007/s10571-010-9594-9, 10.1007/s10571-010-9600-2, 10.1007/s10571-010-9606-9, 10.1007/s10571-010-9620-y.

Immunohistochemical characterisation of differentiated CAD cells: expression of peptides and chromogranins

The CNS-derived cell line, CAD cell line, when grown in a protein free medium (PFM), differentiates to neuron-like cells with very long processes. It was previously studied biochemically and found to express TH activity, some neurospecific proteins, but no glial proteins. We have now further studied the CAD cells and focused on the expression of various neuropeptides, GAP-43 and GFAP. All peptides studied were present, including TH, but also GFAP, in contrast to earlier studies. A different kind of processes, short, slender and distributed like a "fringe" around cell body and along processes was observed, NESP55 but not other chromogranins was present in these "fringes", GAP43 showed some degree of overlapping with NESP55. The results show that even after differentiation in PFM, the CAD cells express a palette of neuropeptides and chromogranins, catecholaminergic markers as well as the glia-specific GFAP. Our efforts to induce exocytosis/endocytosis from the peptide granules by high K+ were, however, unsuccessful. Due to long processes, the CAD cells may represent a good model for studying intracellular transport, and, since the cells express both neuronal and glial characteristics, it may be useful for investigating the influence of different trophic/growth factors on the expression of various neuronal characteristics.

MDMA (ecstasy) effects in pubescent rats: Males are more sensitive than females

In Experiment 1, we assessed the effects of 3,4-methylenedioxymethamphetamine (MDMA) on locomotor activity in pubescent male and female Long–Evans rats. Thirty-nine day old rats were injected ip with 10 mg/kg of MDMA (ambient temperature 25 °C) three times at 2 h intervals. Initially, females showed greater locomotor activation by the drug than males, however after the second injection, males showed greater hyperlocomotion. After the third injection, 3 of 10 females and all of the males died. In the surviving females, we observed serotonin depletion in cortex and hippocampus, but catecholaminergic markers were unaltered. In Experiment 2, male and female rats were repeatedly injected with saline or 2, 5 or 10 mg/kg MDMA and body temperature was measured (ambient temperature 21.5 °C). After the third injection of 10 mg/kg MDMA, the MDMA-induced hyperthermia was greater in males than in females (about + 0.8 °C); at the lower dose, no difference was observed. Probably because of the lower ambient temperature, only 1 female and 2 males succumbed to the MDMA treatment, and MDMA induced less serotonin depletion than in the first experiment, with no difference between females and males. Thus, pubescent males appear to be more sensitive than females to locomotor and hyperpyretic effects of MDMA. This sex-dependent effect, which is at variance with previously reported dimorphisms in psychostimulant effects, is discussed in terms of possible differences in dopamine D 1 and D 2 receptors at pubescence, or other factors related to drug metabolism.

Effects of adrenal medulla graft on recovery of GABAergic and dopaminergic neuron deficits in mice: behavioural, pharmacological and immunohistochemical study

We studied the capacity of adrenal medullary transplant to restore the deficits of GABAergic and dopaminergic neurons in mice injected with quinolinic acid (QA), using an open field test as well as pharmacological and immunohistochemical techniques. We analysed behavioural traits—total locomotor activity, peripheral and central activities, grooming, leaning and rearing in the QA-lesioned mice and mice that had undergone adrenal medulla (AM) transplantation. We found that the adrenal transplant recovered a loss of GABAergic neurons. It reduced QA-induced hyperactivity in locomotion and improved emotional indices. In addition, immunohistochemical studies of catecholaminergic markers—tyrosine hydroxylase (TH), dopamine (DA) and neuronal vesicular monoamine transporter type 2- and a single post-trial injection of tetrabenazine (TBZ; 5 mg/kg) indicated that catecholamines-synthesising chromaffin cells in the AM grafts were also involved in the beneficial effects. A likely interpretation of this behavioural pattern of results is that adrenal medullary transplants set into play an interaction between GABAergic and DAergic factors. Our results may contribute to the clarification of the beneficial effects of AM transplants in striatal function.

SSR2(a) receptor expression and adrenergic/cholinergic characteristics in differentiated SH-SY5Y cells.

Somatostatin (SS) is an inhibitory regulator of secretory and proliferative responses that activates a group of receptors in the plasma membrane termed SSR1-5. SSR2 is one of the most abundant SSR, which also is expressed in high numbers in many neuroendocrine tumor types. Here, we describe a study of the presence and intracellular localization of the spliced variant SSR2(a) and its endogenous ligand SS in the cultured human neuroblastoma (NB) cell line, SH-SY5Y, by immunohistochemistry and confocal laser scanning. The integral neuronal synaptic vesicle membrane proteins synaptophysin (p38) and SV2 were studied, as well as the IR of catecholaminergic and cholinergic markers. RA treatment was used as an inducer of neuronal-like differentiation in our SH-SY5Y cell line. After the treatment, the presence of catecholaminergic markers (including NPY) decreased while the cholinergic markers (including VIP) increased. p38 and SV2 as well as VIP were shifted into the rather long neuritic processes, indicating efficient intracellular transport. The SSR2(a) protein was significantly increased by RA treatment, but only minor increases in mRNA for this receptor protein could be seen. No subcellular co-localization between p38/SV2 and the cytoplasmic granular receptor material was demonstrated. The SSR2(a) receptor ligand SS was found to be present not only in the cytoplasm but also in the nucleus, and more strongly so after RA treatment. The possible reason for this may be that this peptide, like other small peptides, may serve as transcription factor, or cofactor.

Differential expression of sympathoadrenal lineage-determining genes and phenotypic markers in cultured primary neural crest cells.

Bone morphogenetic protein-2 (BMP-2) promotes the development of primary neural crest cells grown in tissue culture to the sympathoadrenal (SA) lineage. Independent studies have characterized the expression patterns of SA-lineage genes in developing chicken embryo; however, studies using cultured primary neural crest cells have characterized only the expression patterns of the catecholaminergic markers, tyrosine hydroxylase (TH) and catecholamines (CAs). To further explore the molecular mechanisms that control SA-cell development using the in vitro model system, it is crucial to define the expression patterns of both the catecholaminergic markers and the genes regulating SA-lineage determination. Accordingly, we defined, in the absence and presence of BMP-2, the temporal expression patterns of TH and CA, the SA lineage-determining genes ASH-1, Phox2a, and Phox2b, the GATA-2 gene, and the pan-neuronal SCG10 gene. Comparison of these data with the reported temporal and spatial patterns of expression in vivo demonstrate that the inductive steps of SA-lineage determination, including the specification of neurotransmitter identity and neuronal fate, are recapitulated in the neural-crest culture system.

Cholinergic denervation-like changes in rat hippocampus following developmental lead exposure

We investigated the effects of developmental lead exposure from embryonic day 16 (E16) through postnatal day 28 (PN28), on cholinergic and catecholaminergic markers in the septohippocampal pathway in rats through fourth month of age. Lead exposure resulted in a persistent 30–40% reduction of [ 3H]hemicholinium-3 ([ 3H]HC-3) binding in the hippocampus through PN120, and 20–30% reduction of septal and hippocampul choline acetyltransferase (ChAT) activity which persisted through PN84 but returned to control levels in both septum and hippocampus at PN112. The muscarinic ligand [ 3H]quinuclidinyl benzylate ([ 3H]QNB) binding was reduced in the septum at PN28 but did not differ significantly from controls at PN56–PN112. Neither short- nor long-term effects of Pb exposure on [ 3H]QNB binding were seen in the hippocampus. Similar to the effects of fimbria-fornix transection, Pb exposure resulted in a long-term 50–90% increase of tyrosine hydroxylase(TH) activity in the hippocampus, although neither treatment affected TH activity in the septum. The lead-induced increase in hippocampul TH was significantly attenuated by superior cervical ganglionectomy. It is concluded that the effects of perinatal lead exposure resemble in several respects those seen following surgical disruption of the septohippocampal pathway in adult animals. The denervation-like effects in the hippocampus may be an important factor in long-term learning and cognitive impairments following developmental exposure to low-levels of lead.

Structures mediating cholinergic reticular facilitation of cortical responses in the cat: effects of lesions in immunocytochemically characterized projections.

Cholinergic afferents to the neocortex controlled by the mesencephalic reticular formation (MRF) are known to transiently facilitate cortical excitability. In an attempt to identify the pathway mediating this effect in the cat visual cortex we combined retrograde tracing techniques with immunocytochemical methods to visualize the acetylcholine-synthesizing enzyme choline acetyltransferase (ChAT). In addition we examined, in acute electrophysiological experiments, whether local neurotoxin injections into nuclei of the basal forebrain interfered with the reticular facilitation of cortical evoked potentials. Cholinergic projections to area 17 originate from different centers in the homolateral substantia innominata/internal capsule, the septal nuclei, and the nuclei of the diagonal band of Broca. No direct cholinergic projection from the MRF to the visual cortex was observed. Retrogradely labelled cells intermingled with ChAT-positive neurons in the brainstem generally revealed immunopositivity for catecholaminergic markers. Local injections of neurotoxins in the substantia innominata blocked reticular facilitation, whereas local lesions of the septal nuclei and the nuclei of the diagonal band had no effect on MRF-induced facilitation. The blockage of the reticular facilitation of cortical evoked responses after unilateral lesions of the substantia innominata was bilateral, suggesting a cooperative interaction between basal forebrain structures of the two hemispheres. The anatomical and physiological data are discussed with respect to possible mechanisms of transient brainstem influences on cortical excitability.

Does adrenal graft enhance recovery of dopaminergic neurons in Parkinson's disease?

A 54-year-old man with a 5-year history of Parkinson's disease was treated with and autograft of adrenal medulla into the right caudate nucleus and died 4 months after surgery. Postmortem examination revealed that the graft was necrotic. It consisted mainly of reticulin and collagen fibrosis without catecholaminergic cell bodies identified either by immunohistochemistry or by in situ hybridization with labeled human tyrosine hydroxylase (TH) cDNA probe. Sparse TH-immunoreactive fibers, which did not stain for dopamine-beta-hydroxylase (DBH), ran through the graft. In contrast, intense staining for these catecholaminergic markers was found in the untransplanted adrenal medulla. Densely packed TH-positive, DHB-negative fibers were found in a restricted zone of the host striatum at the periphery of the graft. This effect was selective since the density of other neurons was not modified. The present study describes an additional patient in whom adrenal medulla autotransplantation failed to improve the parkinsonian disability. It suggests, however, that adrenal medulla grafts may stimulate the sprouting of striatal dopaminergic fibers in a limited zone of the grafted striatum.

Transient catecholaminergic (TC) cells in the vagus nerves and bowel of fetal mice: Relationship to the development of enteric neurons

Catecholaminergic cells are transiently present during development of the fetal murine bowel. These transient catecholaminergic (TC) cells appear at Day E10, but by Day E13 can no longer be detected. In order to evaluate the hypothesis that these cells are the precursors of enteric neurons, we investigated the possibilities that TC cells coexpress neuronal and catecholaminergic markers, that they can be found along the presumed path followed by crest-derived cells migrating to the gut, and that they are proliferating. TC cells were identified immunocytochemically using polyclonal or monoclonal antibodies to tyrosine hydroxylase (TH). At Day E9.5, TH-immunoreactive cells were observed to be present along the wall of the primordial esophagus in lines that extended from the developing nodose ganglia down to the boundary of the stomach. At Day E9.5, TC cells were absent from the remaining foregut. These lines of esophageal TH-immunoreactive cells became continuous with similar cells in the wall of the stomach and duodenum on Day E10. Coincident expression of neurofilament immunoreactivity was seen in all of the esophageal TH-immunoreactive cells present at Day E9.5, as well as in the entire set of esophageal and lower enteric TH-immunoreactive cells present at Day E10 (or later); moreover, at Days E9.5 and E10, all of the neurofilament-immunoreactive cells in the esophagus, stomach, or duodenum were also TH-immunoreactive. In contrast, neurofilament immunoreactivity was not expressed by the endodermally derived pancreatic duct and islet cells, which were also TH-immunoreactive; nor could expression of neurofilament immunoreactivity be detected in the TH-immunoreactive cells of the nodose ganglia. It was not until Day E11 that neurofilament-immunoreactive cells, which did not coexpress TH immunoreactivity (the definitive phenotype of enteric neurons) began to appear in the gut. Vagal axons reached as far distally as the nodose ganglion on Day E9.5, the esophagogastric junction on Day E10, and did not enter the stomach until Day E11. When the vagus nerves reached their level, the TH-immunoreactive cells in the wall of the esophagus came to lie among the nerve fibers. TH-immunoreactive cells are thus present on the pathway ultimately followed by the vagus nerves, but they develop before vagal fibers reach their level. The vagal TH-immunoreactive cells, therefore, are probably not initially migrating on vagal fibers, but appear instead to be overtaken by the descending vagus nerves. The TH-immunoreactive cells in the nodose ganglia and vagus nerves disappear in a proximodistal sequence and, except for vagal paraganglia, TH-immunoreactive cells are gone from the vagus nerves by Day E16. In addition to TH immunoreactivity, vagal and enteric TC cells were found to contain the immunoreactivity for dopamine β-hydroxylase (DBH) and aromatic l-amino acid decarboxylase. Unlike the transient TH-immunoreactive cells of the nodose ganglia, vagal and enteric TC cells displayed intense formaldehyde-induced histofluorescence, indicating that they contain an endogenous catecholamine. In addition, both types of TC cells accumulated [ 3H]norepinephrine ([ 3H]NE) by a mechanism that could be inhibited by desmethylimipramine. Vagal and enteric TC cells, like mature enteric neurons, also exhibited acetylcholinesterase activity and, in whole mount preparations, could be seen to have extended neurites that formed a network, apparently connecting clusters of the cells. Two hours after injection of bromodeoxyuridine, the label was detected immunocytochemically in the nuclei of a subset of both vagal and enteric TC cells (identified by DBH immunoreactivity); therefore, the vagal population, like the enteric TC cell population, is a proliferating one. Their expression of neurofilament immunoreactivity indicates that vagal and enteric TC cells are developing along a neuronal lineage and thus are probably derived from the neural crest. Since these cells are proliferating, they are not neurons; however, they are likely to be neuronal precursors. The phenotypic properties vagal TC cells share with enteric TC cells, their location in the vagal pathway, the timing of their appearance, and their sequence of disappearance are consistent with the ideas that vagal and enteric TC cells belong to the same population and are migrating precursors of enteric neurons.

Aminergic systems in Alzheimer's disease and Parkinson's disease.

Biochemical markers for serotoninergic and catecholaminergic neurons in frontal and temporal poles were examined post mortem in brains of patients with Alzheimer's disease, Parkinson's disease, and the two combined. Binding of [3H] citalopram to serotoninergic uptake sites and levels of serotonin were decreased by 40 to 50% in brains of persons in each disease category. In contrast, significant reductions of catecholaminergic markers were not detected. In all three disease groups, the choline acetyltransferase activity was reduced by 50 to 60%. Binding sites for adenosine (A1), muscarinic cholinergic, phencyclidine, beta-adrenergic, and calcium antagonist receptors were unchanged. We conclude that substantial damage to serotoninergic neurons occurs in persons with Parkinson's and Alzheimer's diseases.

Neurochemical characterization of embryonic brain development in trisomy 19 (Ts19) mice: implications of selective deficits observed for abnormal neural development in aneuploidy.

In this study, we examined the neurochemical profiles of selected brain regions (cerebral hemispheres, diencephalon/brainstem) in fetal (day 14 to 18 gestation) trisomy 19 (Ts19) mice. The neurochemical characteristics we observed in Ts19 mice were quite different from those we observed previously in Ts16 mice. Choline acetyltransferase (ChAT) activity was reduced significantly in the cerebral hemispheres, but not in the brainstem/diencephalon, of the fetal Ts19 mouse brain, suggesting a selective vulnerability of telencephalic cholinergic neurons. Additionally, the activity of glutamic acid decarboxylase (GAD) was reduced significantly in both hemispheres and diencephalon/brainstem of late gestation Ts19 fetuses, suggesting a selective vulnerability of GABAergic neurons as well. While the levels of catecholaminergic and dopaminergic markers were reduced significantly at late gestational ages, the relative rate of turnover of dopamine (DA), measured by the ratio of DOPAC/DA, was elevated significantly in Ts19 mice. Neither reduction in the thickness of various cellular zones of the cerebral cortex nor reduced cell density of the cerebral cortex accounts for the alterations in neurochemical parameters observed in Ts19 mice. These results suggest that the effects of the triplication of specific genes on the respective chromosomes, rather than a generalized disruption of developmental homeostasis resulting from extra chromosomal material, may produce selective alterations in neurochemical and neuroanatomical markers observed in these two mouse trisomies.