Autonomic nervous system structures: structural and functional correlates. Introduction.
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Animals↗
Biomedical subjects
I L Chen
Publications and source records attributed to I L Chen.
Synaptic morphology of substance P terminals on catecholamine neurons in the commissural subnucleus of the nucleus tractus solitarii in the rat.
The ultrastructure of substance P-containing nerve terminals synapsing on catecholamine neurons in the rat commissural subnucleus of the nucleus tractus solitarii (NTScom) was studied using a double immunocytochemical labeling technique. Although there were numerous tyrosine hydroxylase-immunoreactive (TH-I) somata present, substance P immunoreactive (SP-I) cell bodies were only occasionally found in the NTScom. At the light microscopic level, many SP-I terminals were seen closely associated with TH-I dendrites and somata. At the electron microscopic level, SP-I terminals synapsing on TH-I structures were also readily encountered. SP-I terminals contained small, clear, and predominantly spherical vesicles (32 +/- 4 nm diameter), as well as large dense-cored vesicles approximately 100 nm in diameter. Postsynaptic TH-I dendritic profiles of various calibers and somata were encountered. These postsynaptic TH-I structures often showed postsynaptic densities. The morphological features of the SP-TH synapses in the present study, that is, the size of synaptic vesicles and the presence of postsynaptic densities, are quite different from those of central carotid sinus afferent synapses reported in our previous study [Chen et al. (1992), J. Neurocytol., 21:137-147]. Therefore, most of the SP terminals of the SP-TH synapses in the NTScom appear not to originate from the carotid sinus afferents. SP-I second-order neurons of the carotid sinus afferent pathway [Chen et al. (1991), J. Auton. Nerv. Syst., 33:97-98] may be one of the possible sources of such terminals.
Afferent Pathways↗
Synaptic connections of central carotid sinus afferents in the nucleus of the tractus solitarius of the rat. II. Connections with substance P-immunoreactive neurons.
A combined transganglionic transport and immunocytochemical technique was used to study the synaptic morphology of central carotid sinus afferents and substance P-immunoreactive neurons in the commissural subnucleus of the nucleus of the tractus solitarius in rats. A large population of substance P-immunoreactive neurons (88.32%) were seen in close association with central carotid sinus afferents by light microscopy. However, many labelled central carotid sinus afferents appeared not associated with substance P-immunoreactive neurons in the nucleus of the tractus solitarius. Substance P-immunoreactive neurons were spindle, pear, or oval-shaped with a short axis ranging from 5 to 11 microns. Their long axis was oriented predominantly in a lateral-medial direction along the path of the central carotid sinus afferents from the solitary tract to the midline. Synaptic contacts between central carotid sinus afferents and substance P-structures, including dendritic profiles of different calibers and somas, were readily found by electron microscopy. Many central carotid sinus afferents were also found in synaptic contact with non-immunoreactive dendrites and somas. Appositions between central carotid sinus afferents and unlabelled axon terminals were common, but only in a few cases were morphological manifestations of synapses revealed. In the latter, the substance P-immunoreactive terminals appeared mostly presynaptic but postsynaptic ones were also encountered. Our data provide the evidence that some of the substance P-immunoreactive cells in the nucleus of the tractus solitarius are 2nd order neurons of the carotid sinus afferent pathway. The possibility that some of the substance P-immunoreactive neurons in the nucleus of the tractus solitarius may be interneurons and mediate carotid sinus afferent inputs to catecholaminergic neurons in the nucleus of the tractus solitarius is considered. Our findings also provide an anatomical substrate for a possible presynaptic modulatory role of central carotid sinus afferents on the inputs from other brain centers to the substance P-neurons in the nucleus of the tractus solitarius.
Afferent Pathways↗
Angiopeptin enhances acetylcholine-induced relaxation and inhibits intimal hyperplasia after vascular injury.
The effects of the somatostatin analogue, angiopeptin (BIM-23014), on neoendothelial function, as evidenced by formation of prostaglandin (PG) I2 and by acetylcholine-induced relaxation (formation of endothelial-derived relaxing factor), were investigated in the rabbit aorta. A balloon catheter injury of the thoracic and abdominal aorta was induced in New Zealand White rabbits. Animals treated with angiopeptin for 2 or 4 wk were compared with untreated rabbits at 2 or 4 wk after the induction of injury, as well as to sham-operated controls. When the rabbits were killed, vascular rings were assessed for arachidonic acid-stimulated PGI2 formation, acetylcholine-induced relaxation, and the degree of intimal hyperplasia. Vascular rings from animals treated with angiopeptin exhibited enhanced acetylcholine-induced relaxation; however, angiopeptin treatment had no effect on arachidonic acid-stimulated PGI2 formation. Intimal hyperplasia in treated animals was reduced by 36%. Treatment with another somatostatin analogue, BIM-23030, did not enhance relaxation or inhibit intimal hyperplasia. These data suggest that treatment with angiopeptin may inhibit intimal hyperplasia in part by its beneficial effect on neoendothelial function.
Acetylcholine↗
Synaptic connections of central carotid sinus afferents in the nucleus of the tractus solitarius of the rat. I. An electron microscopic study.
A transganglionic transport technique was used to study the synaptic connections of the central carotid sinus afferents in the nucleus of the tractus solitarius of the rat by electron microscopy. The caudal part of the nucleus was profusely innervated. Labelled fibres extended to the contralateral nucleus, and to the ipsilateral dorsal motor nucleus of the vagus nerve, nucleus ambiguus, spinal nucleus of the trigeminal nerve and the area postrema. The labelled terminals were densely packed with clear, predominantly spherical vesicles about 50 nm in diameter and a few often swollen mitochondria. The terminals synapsed on dendrites of various calibres, spindle- or pear-shaped somal profiles with short axes lesser than 8 microns, and axon terminals. In axo-axonal synapses, most labelled terminals appeared to be presynaptic. Frequently, profiles of labelled terminals were in direct apposition with one another. The latter may represent the morphological substrate of the interaction between baro- and chemoreceptor inputs in the nucleus of the tractus solitarius and warrants further study. The present results indicate that in addition to direct inputs, the carotid sinus afferents are able to influence second-order neurons in the nucleus of the tractus solitarius indirectly through presynaptic modulation.
Afferent Pathways↗
Differential recovery of prostacyclin and endothelium-derived relaxing factor after vascular injury.
Differential recovery of prostacyclin and endothelium-derived relaxing factor after vascular injury. Am. J. Physiol. 262 (Heart Circ. Physiol. 31): H1449-H1457, 1992. The recovery of prostacyclin (prostaglandin I2, PGI2) synthesis and endothelium-derived relaxing factor (EDRF) activity, as demonstrated by acetylcholine (ACh)-induced relaxation, by rabbit aorta was examined up to 8 wk after balloon catheter-induced injury. Following injury, basal 6-keto-PGF1 alpha formation was decreased acutely; however, after 3 wk it was not different from control. Arachidonic acid-stimulated 6-keto-PGF1 alpha formation was decreased, returning to control levels at 3 and 8 wk for thoracic and abdominal aorta, respectively. ACh-induced relaxation did not return to control levels over the 8-wk study. Initiation of reendothelialization with a layer of hyperplastic endothelial cells overlying subendothelial fibrosis and intimal hyperplasia were present at 2-3 wk. Intimal hyperplasia appeared 2 wk after injury and progressed throughout the period of the study. These data indicate that following balloon catheter-induced injury the formation of both PGI2 and EDRF is reduced and that recovery follows a differential time course. In addition, the recovery of PGI2 formation did not coincide with the attenuation of intimal hyperplasia, whereas the relationship between EDRF formation and intimal hyperplasia is uncertain.
Acetylcholine↗
The pretectal complex of the cat: cells of origin of projections to the pulvinar nucleus.
The pretectal projection to the pulvinar nucleus in the cat was examined using the retrograde transport of wheat germ agglutinin-horseradish peroxidase. These data show that both visual and non-visual areas of the pretectal complex contribute to the projection. Specifically, large numbers of labeled neurons are located within the pretectal olivary nucleus with a substantial number of labeled neurons observed within the nucleus of the optic tract. Labeled neurons are also located within the medial, anterior and posterior nuclei, but not to the degree observed in the other pretectal nuclei. Morphometric analysis of labeled and Nissl-stained neurons indicate that the pretectopulvinar pathway is not correlated to any single cell size.
Animals↗
Light and electron microscopic studies of diet-induced hepatic changes in mice.
Adult mice were fed a choline-deficient ethionine enriched (CDE) diet for 24, 48 or 72 h. They were then fasted for 24 or 48 h prior to sacrifice. All tissues were studied by light and electron microscopy. Animals fed the CDE diet for 24 h exhibited cells with vacuolated cytoplasm, and the accumulation of lipid in these cells was clearly abnormal. Animals fed the CDE diet for 24 h and subsequently a regular diet for 48 h displayed normal hepatocytes, suggesting that the alterations at 24 h were reversible. Following 48 or 72 h of feeding the CDE diet, abundant lipid-laden cells were observed in the hepatic lobules, and at the electron microscope level these cells were undergoing frank degeneration. Evidence indicated that changes after 48 or 72 h were irreversible.
Animals↗
Dopamine beta-hydroxylase-like immunoreactivity in the rat and cat carotid body: a light and electron microscopic study.
Immunocytochemical localization of dopamine beta-hydroxylase (DBH) was used to study the synthesis and storage sites of norepinephrine (noradrenaline) in the rat and cat carotid bodies. In the rat carotid body some parenchymal cells exhibited strong DBH-like immunoreactivity (DBH-I), while others displayed only faint DBH-I. In a typical parenchymal cell cluster, most cells with strong DBH-I were irregular in shape and appeared to partially surround those with weak DBH-I which usually were rounded in contour. In the cat carotid body most parenchymal cells showed a strong to moderate DBH-I. In both the rat and cat carotid bodies varicose nerve fibres with DBH-I were associated primarily with blood vessels. All autonomic ganglion cells examined, which were associated with the rat carotid body, showed DBH-I. Electron microscopy revealed that most DBH-I in the strongly positive cells of the rat carotid body was associated with dense granules (possibly corresponding to dense-cored vesicles of various sizes), although some was found in other sites. In oval cells with less DBH-I, reactivity resided in some of the large granules. In the cat carotid body the glomus cells contained more granules of various sizes and shapes than did those of the rat carotid body. Most of the cat glomus cell granules exhibited DBH-I activity. Our results indicate that some of glomus cells in the rat and most of the glomus cells in the cat contain DBH and therefore may be sites of norepinephrine synthesis.
Animals↗
Effects of dibutyryl adenosine 3',5'-cyclic monophosphate on erythropoietin production in human renal carcinoma cell cultures.
A human renal carcinoma from a patient with erythrocytosis, serially transplanted into athymic nude mice, was grown in primary monolayer cell cultures. After reaching confluency, the cultured cells formed multicellular hemicysts (domes), which became more abundant as the cultures approached saturation density. Erythropoietin (Ep) production by this renal carcinoma in culture was only slightly increased at the time of semiconfluency but showed a marked increase after the cultures reached confluency, in parallel with dome formation. Dibutyryl adenosine 3',5'-cyclic monophosphate significantly (P less than .01) stimulated Ep production and dome formation in the semiconfluent and confluent cultures of the renal carcinoma.
Animals↗
Two types of glomus cell in the rat carotid body as revealed by alpha-bungarotoxin binding.
Horseradish peroxidase (HRP)-conjugated alpha-bungarotoxin (alpha Bgt) was used to localize alpha Bgt-acetylcholine receptor sites in the rat carotid body. Two types of glomus cell were differentiated on the basis of the staining of their plasma membranes by the conjugate: type A, devoid of staining or only partly stained; and type B, exhibiting staining over the entire cell surface. The parts of type A glomus and supporting cells stained were always in direct apposition to type B glomus cells. It is concluded that type B glomus cells are possibly the only cell types exhibiting specific binding sites of alpha Bgt. Other morphological characteristics and quantitative studies indicated that the type A and type B glomus cells presented in this study were equivalent to those described in the rat carotid body by other investigators (McDonald & Mitchell, 1975). alpha Bgt-HRP staining facilitated the observation of the distribution pattern of glomus cells in the parenchyma: type A glomus cells were arranged in groups and often showed polarity toward neural elements and sinusoidal capillaries; and clusters of type B glomus cells were frequently situated in a demilune -like fashion over groups of type A glomus cells. Because of differences in morphology, synaptology, alpha Bgt-binding affinity, and polarity toward the blood vessels, we propose that type A and type B glomus cells in the rat carotid body represent functionally distinct cell types.
Acetylcholine↗
Erythropoietin production in long-term cultures of human renal carcinoma cells. The role of cell population density.
The present studies report the maintenance of erythropoietin (Ep) production in long-term cultures of a human renal carcinoma from a patient with erythrocytosis. The renal carcinoma cells were grown and maintained in monolayer cultures for 7 months. They were serially passaged every 2-3 weeks when the cultured cells reached confluency. Ep levels measured with a sensitive radioimmunoassay in the spent culture media of the cells in the stage of semiconfluent or confluent density were less than 20 and 30 mU/ml, respectively, throughout the period of 15 successive passages. However, when the renal carcinoma cells were maintained in culture without passage after reaching confluency, Ep levels in the spent media of these cells reproducibly showed an exponential increase to more than 300 mU/ml at the time of saturation density. The importance of cell population density in Ep production by the renal carcinoma cell cultures was further confirmed by the observation that the cultures with higher seeding density reached confluency earlier and began an exponential increase in Ep production sooner than those cultures with lower seeding density.
Carcinoma, Renal Cell↗
Role of endogenous prostaglandin E2 in erythropoietin production and dome formation by human renal carcinoma cells in culture.
Studies were carried out on the role of endogenous prostaglandin E2 (PGE2) in erythropoietin (Ep) production and dome formation in primary monolayer cultures of a human renal carcinoma from a patient with erythrocytosis that has been serially transplanted into BALB/c athymic nude mice. The metabolism of [14C]arachidonic acid (14C-AA) by cultured renal carcinoma cells, which were plated in 25-cm2 flasks at a density of 2 X 10(4) cells/cm2 and grown for 6, 12 (confluence, 13 X 10(4) cells/cm2), 16, 24, and 30 d in Eagle's minimum essential medium (MEM) supplemented with 10% fetal bovine serum, was examined by using radiometric thin-layer chromatography (TLC). TLC revealed PGE2 to be the major metabolite of 14C-AA produced by the cultured cells throughout the 30 d of cultivation. In addition, the cultured cells at each time period were incubated for 24 h in 5 ml of serum-free Eagle's MEM and the levels of PGE2 and Ep in the incubated media were measured via radioimmunoassay. PGE2 levels in the serum-free media incubated with the cultured cells grown for 6 d were significantly (P less than 0.001) elevated (174 +/- 2.5 pg/ml, n = 5), compared with the unincubated control media (1.5 +/- 0.19 pg/ml, n = 5) and gradually decreased at each time period to 97.6 +/- 4.4 pg/ml (n = 5) at 30 d. On the other hand, the levels of Ep in the incubated media of the cells grown for 6 d were 11.5 +/- 0.52 mU/ml (n = 5) compared with 7.6 +/- 0.62 mU/ml (n = 5) in the control media. However, after the cultured cells became confluent, the levels of Ep in the incubated media showed a marked increase to 222.9 +/- 5.26 mU/ml (n = 5) at 30 d of cultivation. Multicellular hemicysts (domes) developed after the cultured cells reached confluence and their numbers increased with increasing time in confluence in parallel with the increase in Ep. Meclofenamate (MF) (3 X 10(-6)-3 X 10(-5) M), a prostaglandin synthesis inhibitor, produced a significant dose-related decrease in PGE2, Ep, and dome formation without producing a significant effect on cell viability in the 30-d cells. This inhibitory effect of MF on Ep production and dome formation was completely abolished by the addition of 10(-8) M PGE2 to the incubation medium. In conclusion, endogenous PGE2 plays an important role in supporting and/or stimulating Ep production and dome formation in cultured renal carcinoma cells.
Animals↗
Erythropoietin production in a primary culture of human renal carcinoma cells maintained in nude mice.
The present studies report erythropoietin (Ep) production in primary cultures of a human renal carcinoma from a patient with erythrocytosis that has been serially transplanted to BALB/c nude mice. The levels of erythropoietin in the culture media were estimated using the exhypoxic polycythemic mouse assay (EHPCMA), fetal mouse liver erythroid colony-forming technique (FMLC), and a radioimmunoassay (RIA). The spent culture media of the exponentially growing cells contained less than 10 mU/ml of Ep measured by RIA. However, after the cells became confluent, Ep levels (RIA) in the spent media showed a marked increase to approximately 300 mU/ml. Ep levels estimated using the FMLC and EHPCMA were approximately 2/3 and 1/10, respectively, of those measured by RIA. Rabbit antiserum to highly purified human urinary Ep (70,400 U/mg protein) was utilized for immunocytochemical (peroxidase-antiperoxidase method) localization of Ep in the cultured cells. Very few of the cells in exponential growth exhibited Ep-like immunoreactivity, whereas intense Ep-like immunoreactivity was observed in the cytoplasm of the cells maintained in culture for a prolonged period after reaching confluency. The most intense staining was observed in some of the cells forming domes. The domes developed after the cells reached confluency, and their numbers increased with increasing time in confluent culture, in parallel with the increase in Ep levels in the spent media. This primary cell culture system of a renal cell carcinoma maintained in nude mice, which produces immunologically and biologically active Ep, may provide a useful model for studies of the mechanism of Ep production.
Animals↗
Ultrastructural localization of ATPase activity in the dog area postrema.
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Adenosine Triphosphatases↗
Light and electron microscopic localization of ATPase in normal and degenerating testes of Syrian hamsters.
The distribution of Mg++-activated ATPase was determined with light and electron microscopy in normal and degenerating seminferous tubules. In the normal animals ATPase was localized in the interface between spermatids and Sertoli cells, in association with the cytoplasmic filaments contained within Sertoli cell processes, and in the lymphatic endothelium. ATPase activity increased in degenerating tubules as observed by light microscopy. Electron microscopic investigations of the degenerating tubules which contained only spermatogonia and Sertoli cells revealed reaction product on the outer surface of the Sertoli cell processes and within the interface between adjacent Sertoli cells. Reactaction product was also observed in the Sertoli cell processes between the cytoplasmic filaments and the cell membrane. Where filaments were absent in Sertoli cell processes, no reaction product was observed. These electron microscopic studies indicate that the increase in ATPase activity in testicular degeneration is probably a relative increase due to a loss of the germinal elements of the tubular epithelium and subsequent apposition of the Sertoli cell processes. We speculate that the ATPase activity localized within the Sertoli cell processes may be involved in providing an energy source for filament motility.
Adenosine Triphosphatases↗
An electron microscopic study on the effects of reserpine on the subclavian glomera of the rabbit.
Young male and female New Zealand white rabbits were given a daily subcutaneous injection of reserpine (Serpasil, Ciba; 3 mg/kg) for two days and were sacrificed 24 hours after the last injection. The subclavian glomera (aortic bodies) were processed for electron microscopy to determine the effects of this biogenic amine depleting agent on the electron-opaque cytoplasmic granules of the parenchymal type I cells. Observations of glutaraldehyde-osmium tetroxide fixed glomera from reserpinized animals showed a slight decrease in granule density of the type I cells. Glomera fixed in glutaraldehyde and incubated in potassium dichromate (pH 4.1) demonstrated a reduction in granule opacity following reserpine treatment. Control glomera incubated in potassium dichromate displayed electron-opaque granules. These results indicate that reserpine does deplete the amines without granule disappearance or changes in granule population. The positive reaction of the control tissue granules to potassium dichromate incubation suggests that the predominant biogenic amines in the electron-opaque granules are unsubstituted monoamines. Persistence of the opaque granules following reserpinization and glutaraldehyde-osmium tetroxide double fixation, may be due to amine-binding protein within the granules. The mode of granule depletion could not be ascertained with certainty.
Animals↗
The fine structure and phosphatase cytochemistry of the golgi complex and associated structures in the sertoli cells of Syrian hamsters.
The Golgi complex in the Sertoli cell of the Syrian hamster is well developed and consists of stacks of cisternae and associated vesicles. The inner- and outermost cisternae of the Golgi stacks are usually moderately dilated and exhibit numerous fenestrations. The middle portions of the intermediate cisternae are greatly flattened and not fenestrated, but toward the periphery these cisternae gradually become dilated and show a few fenestrations. On the inner aspect of the Golgi stacks the following structures are seen frequently: (1) one or two series of linearly arrayed circular profiles some of which are interconnected by tubules; (2) networks of anastomosing tubules with circular or oval meshes (800 to 1200 A in diameter); and/or (3) irregularly disposed tubules. The circular profiles and tubules are approximately 450 A in diameter. Acid phosphatase activity was localized in these anastomosing tubules when the tissues were incubated for more than one hour in a modified Gomori's medium (Barka and Anderson, 1963). Strong thiamine pyrophosphatase activity was demonstrated in the inner one to three cisternae of the Golgi stacks but not in the associated tubules. The system of the Golgi associated tubules is morphologically and histochemically distinct from the Golgi stacks and is probably equivalent to the Golgi-endoplasmic reticulum-lysosome system (GERL) in other cell types. The three dimensional aspects of the GERL-equivalent system are discussed.
Acid Phosphatase↗