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D M Katz

Publications and source records attributed to D M Katz.

At least 55 records · Page 3Linked to original sources
PubMed1986

Expression and regulation of catecholaminergic traits in primary sensory neurons: relationship to target innervation in vivo.

Catecholaminergic (CA) phenotypic characteristics have recently been detected in adult sensory neurons, demonstrating that CA expression in the periphery extends beyond the sympathoadrenal axis. Consequently, we may now determine whether common principles underlie CA phenotypic organization in functionally and embryologically diverse populations of peripheral neurons. To begin defining sensory transmitter regulation, the present study examined the relationship of CA expression to sensory target innervation in cranial nerve ganglion cells of the adult rat. Retrograde labeling combined with tyrosine hydroxylase (TH) immunocytochemistry indicated that 80-90% of CA sensory neurons in the glossopharyngeal petrosal ganglion project peripherally in the carotid sinus nerve (CSN). Most of these cells innervate a single target, the carotid body, revealing a striking correlation between CA expression and the pattern of sensory target innervation. Furthermore, CSN transection resulted in a transient marked decrease in TH catalytic activity and immunoreactivity within 1 week. Activities returned to normal by 3 weeks. Thus, axotomy reversibly decreased sensory TH, reproducing effects observed with central CA neurons (Ross et al., 1975), but differing in certain aspects from observations with sympathetic CA neurons (Cheah and Geffen, 1973; Kessler and Black, 1979). To determine whether disruption of axonal transport itself decreased TH in petrosal neurons, colchicine cuffs were placed around the intact CSN. Colchicine blockade reproduced the effects of axotomy, suggesting that deranged transport, and not axonal damage per se, altered TH. Finally, we studied the role of sensory projections to the CNS by examining petrosal TH after glossopharyngeal nerve rhizotomy. In contrast to sequelae of peripheral axotomy, rhizotomy did not alter TH, suggesting that projections to the periphery predominate in regulation of sensory TH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Topographic representation of visceral target organs within the dorsal motor nucleus of the vagus nerve of the pigeon Columba livia.

Our previous work (Katz and Karten, '83a J. Comp. Neurol. 217:31-46 demonstrated that the dorsal motor nucleus of the vagus nerve (DMN complex) in the pigeon is composed of cytoarchitecturally distinct subnuclei that are distinguished by the size, shape, position, and cytochemical characteristics of their constituent neurons. In view of the diversity of target organs innervated by the vagus nerve, we sought to determine whether the subnuclear heterogeneity of the DMN complex is related to the pattern of target innervation. To test this possibility, retrograde tracing techniques were used to define the subnuclear localization of vagal motoneurons that innervate individual vagal target organs. The distribution of horseradish peroxidase (HRP)-labeled motoneurons within the DMN complex was studied following application of HRP to the cut central end of individual vagal nerve branches and after injection of the tracer into vagal target tissues. In addition, we examined the distribution of acetylcholinesterase depletion within the DMN complex following transection of individual vagal branches. Our data demonstrate that individual vagal target organs have discrete and topographic representations within cytoarchitecturally distinct subnuclei of the DMN complex. Therefore, in the pigeon, the subnuclear distribution of vagal motoneurons plays a critical role in the organization of descending vagal motor pathways. Segregation of visceral representations within the DMN complex may provide a mechanism for organizing functionally diverse afferent inputs to target-specific populations of vagal motoneurons.

Abdomen↗
PubMed1985

High-affinity uptake of serotonin into immunocytochemically identified astrocytes.

Primary cultures of astrocytes from neonatal rat brain were incubated with tritiated serotonin. After fixation they were stained by immunofluorescence for the astrocyte-specific marker glial fibrillary acidic protein and processed for autoradiography. Silver grain density was increased over cells positive for glial fibrillary acidic protein and was reduced to background levels when sodium was omitted from the medium or the specific inhibitors of serotonin uptake fluoxetine and chlorimipramine were present. The results indicate that mammalian astrocytes can take up serotonin by a sodium-dependent, high-affinity system previously thought to be the exclusive property of serotonergic nerve endings.

Animals↗
PubMed1985

Kinetics and autoradiography of high affinity uptake of serotonin by primary astrocyte cultures.

Primary astrocyte cultures prepared from the cerebral cortices of neonatal rats showed significant accumulation of serotonin (5-hydroxytryptamine; [3H]-5-HT). At concentrations in the range of 0.01 to 0.7 microM [3H]-5-HT, this uptake was 50 to 85% Na+ dependent and gave a Km of 0.40 +/- 0.11 microM [3H]-5-HT and a Vmax of 6.42 +/- 0.85 (+/- SEM) pmol of [3H]-5-HT/mg of protein/4 min for the Na+-dependent component. In the absence of Na+ the uptake was nonsaturable. Omission of the monoamine oxidase inhibitor pargyline markedly reduced the Na+-dependent component of [3H]-5-HT uptake but had a negligible effect on the Na+-independent component. This suggest significant oxidative deamination of serotonin after it has been taken up by the high affinity system, followed by release of its metabolite. We estimated that this system enabled the cells to concentrate [3H]-5-HT up to 44-fold at an external [3H]-5-HT concentration of 10(-7) M. Inhibition of [3H]-5-HT uptake by a number of clinically effective antidepressants was also consistent with a specific high affinity uptake mechanism for 5-HT, the order of effectiveness of inhibition being chlorimipramine greater than fluoxetine greater than imipramine = amitriptyline greater than desmethylimipramine greater than iprindole greater than mianserin. Uptake of [3H]-5-HT was dependent on the presence of Cl- as well as Na+ in the medium, and the effect of omission of both ions was nonadditive. Varying the concentration of K+ in the media from 1 to 50 mM had a limited effect on [3H]-5-HT uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Neurotransmitter plasticity at the molecular level.

Contrary to long-held assumptions, recent work indicates that neurons may profoundly change transmitter status during development and maturity. For example, sympathetic neurons, classically regarded as exclusively noradrenergic or cholinergic, can also express putative peptide transmitters such as substance P. This neuronal plasticity is directly related to membrane depolarization and sodium ion influx. The same molecular mechanisms and plastic responses occur in mature as well as developing neurons. Further, contrary to traditional teaching, adult primary sensory neurons may express the catecholaminergic phenotype in vivo. Transmitter plasticity is not restricted to the peripheral nervous system: ongoing studies of the brain nucleus locus ceruleus in culture indicate that specific extracellular factors elicit marked transmitter changes. Consequently, neurotransmitter expression and metabolism are dynamic, changing processes, regulated by a variety of defined factors. Transmitter plasticity adds a newly recognized dimension of flexibility to nervous system function.

Adrenal Medulla↗
PubMed1984

Transient cimetidine resistance.

We report the phenomenon of transient resistance to cimetidine in a 27-year-old healthy, asymptomatic woman who underwent a 5-day gastric intubation study as part of a research protocol. Despite normal blood levels after orally administered cimetidine, this subject had no gastric acid suppression in response to the drug on 2 days of the protocol. On two other occasions, however, she responded appropriately to cimetidine by raising her intragastric pH, reaching peak cimetidine blood levels that were similar to those on the days that she had not responded. The cause for this variable effect of cimetidine on intragastric pH is not known, but might reflect a cholinergic response to stress. Other mechanisms for cimetidine resistance are also discussed.

Adult↗
PubMed1983

Visceral representation within the nucleus of the tractus solitarius in the pigeon, Columba livia.

This study describes the distribution of organ-specific populations of vagal afferent fibers within the nucleus of the solitary tract (nTS) in the pigeon. The central projections of vagal sensory neurons were visualized by the centripetal and trans-ganglionic transport of horseradish peroxidase from either the central cut ends of peripheral vagal branches or from HRP injection sites in peripheral vagal target tissues. This paper also includes a detailed description of the cytoarchitectural organization of the nTS in the pigeon based on studies of Nissl-stained material. Vagal afferent fibers that innervate different peripheral target organs are partially segregated within cytoarchitecturally distinct subnuclei of the nTS. Gastrointestinal afferents, for example, project primarily to medial subnuclei. On the other hand, pulmonary, and on the basis of earlier studies, cardiovascular afferents, project primarily to lateral subnuclei. Moreover, the rostral to caudal distribution of gastrointestinal afferents corresponds to the rostrocaudal topography of the gastrointestinal tract. In addition, our data demonstrate a projection of gastrointestinal afferents to the lateral descending tract of the trigeminal nerve that appears to terminate in the external cuneate nucleus. The cytoarchitectural organization of visceral representations within the pigeon nTS corresponds closely to recent descriptions of this cell group in mammals. Comparison of our results with studies of the central connections of nTS neurons suggests that the subnuclear distribution of organ-specific vagal afferents within nTS plays a critical role in the organization of ascending and descending visceral afferent pathways.

Animals↗
PubMed1983

Subnuclear organization of the dorsal motor nucleus of the vagus nerve in the pigeon, Columbia livia.

The present study is the first of two papers describing the cytoarchitectural and functional organization of the dorsal motor nucleus of the vagus nerve (DMN complex) in the pigeon. This paper describes the distribution of vagal motoneurons within the pigeon brainstem, and the cytoarchitectural organization of the DMN complex. Our description is based on studies of Nissl-stained tissue from normal animals and on experimental studies using retrograde tracing techniques. Cells within the DMN complex were classified according to size, morphology, location, and staining characteristics. These studies demonstrate that vagal motoneurons are localized to (1) the DMN complex, (2) the region of the nucleus ambiguus, and (3) the region of the reticular formation extending between the dorsal motor nucleus and the nucleus ambiguus. Our cytoarchitectural indicate that the DMN complex is composed of at least 11 cytoarchitecturally distinct subnuclei. These subnuclei are evident in normal tissue and are especially prominent in cases where HRP backfilling produces a Golgi-like staining of the motoneurons. The subnuclei can be distinguished by their positions within the DMN complex and by the size, shape, and staining characteristics of their constituent neurons. Comparison of these data with studies in other species indicates similar patterns of cytoarchitectural organization in the DMN complex of some mammals. The diversity of nuclear subgroups within the DMN complex may be related to the heterogeneity of target organs innervated by these cells.

Acetylcholinesterase↗
PubMed1983

Expression of catecholaminergic characteristics by primary sensory neurons in the normal adult rat in vivo.

Expression of catecholaminergic characteristics by primary sensory neurons was examined in the vagal nodose and glossopharyngeal petrosal ganglia of the normal adult rat in vivo. Catecholaminergic phenotypic expression was documented by immunocytochemical localization of tyrosine hydroxylase (TyrOHase; EC 1.14.16.2), radiochemical assay of specific TyrOHase catalytic activity, and cytochemical localization of formaldehyde-induced catecholamine fluorescence (FIF) within principal ganglion cells. The TyrOHase-containing cells exhibited morphologic features typical of primary sensory neurons, such as an initial axon glomerulus and a single, bifurcating neurite process. These cells were distinguished from TyrOHase- and FIF-positive small intensely fluorescent cells by size, morphology, and staining intensity. TyrOHase-containing neurons appeared to be insensitive to neonatal treatment with 6-hydroxydopamine, thereby distinguishing them from sympathetic neurons. Nodose and petrosal ganglia of adult rats exhibited TyrOHase catalytic activity, linear with respect to tissue concentration over a 10-fold range, indicating that the immunoreactive enzyme was functional. Transection of specific ganglionic nerve roots depleted TyrOHase catalytic activity and neuronal immunoreactivity within the petrosal ganglion, suggesting that target organ innervation regulates enzyme levels within ganglion perikarya. Our study indicates that primary sensory neurons express catecholaminergic transmitter traits in the normal adult rat. Consequently, in the periphery, catecholaminergic characters are not restricted to the sympathoadrenal axis but are expressed by functionally and embryologically diverse populations of autonomic neurons.

Animals↗
PubMed1980

Substance P in the vagal sensory ganglia: localization in cell bodies and pericellular arborizations.

The distribution of Substance P-like immunoreactivity in the jugular and nodose ganglia of rabbits and pigeons has been studied using immunocytochemical staining techniques. Substance P-like immunoreactivity is localized to neuronal cell bodies and processes in the jugular and nodose ganglia, and to pericellular fiber plexi in the nodose ganglia of both species. The numbers and sizes of cells which exhibited Substance P-like immunoreactivity in each ganglion were determined using quantitative morphometric techniques. The distribution of Substance P-like immunoreactivity in the rabbit and pigeon vagal sensory ganglia is characterized by several general features. In most of the ganglia, immunoreactive neurons factor into discrete types which can be distinguished from one another, and from non-immunoreactive neurons, by size. In addition, immunoreactive nodose and jugular ganglion cells, respectively, are distinguishable on the basis of size. Finally, a considerably high percentage of immunoreactive neurons is found in the jugular ganglion than in the nodose ganglion. Substance P-like immunoreactivity was also seen in pericellular fiber plexi which encircle individual neurons in the nodose ganglion of rabbits and pigeons. These plexi are composed of varicose fibers which appear to terminate as boutons on the surface of the cells which they encircle. The distribution of Substance P-like immunoreactivity within the vagal sensory ganglia is discussed with respect to the possible peripheral targets and functions of Substance P-containing vagal afferents. Our findings suggest that Substance P-containing vagal sensory neurons are involved in a variety of visceral and somatic afferent functions.

Animals↗