Localization Of Biogenic Amines Research Articles

Localization of biogenic amines in the foregut of Aplysia californica: catecholaminergic and serotonergic innervation.

This study examined the catecholaminergic and serotonergic innervation of the foregut of Aplysia californica, a model system in which the control of feeding behaviors can be investigated at the cellular level. Similar numbers (15-25) of serotonin-like-immunoreactive (5HTli) and tyrosine hydroxylase-like-immunoreactive (THli) fibers were present in each (bilateral) esophageal nerve (En), the major source of pregastric neural innervation in this system. The majority of En 5HTli and THli fibers originated from the anterior branch (En(2)), which innervates the pharynx and the anterior esophagus. Fewer fibers were present in the posterior branch (En(1)), which innervates the majority of the esophagus and the crop. Backfills of the two En branches toward the central nervous system (CNS) labeled a single, centrifugally projecting serotonergic fiber, originating from the metacerebral cell (MCC). The MCC fiber projected only to En(2). No central THli neurons were found to project to the En. Surveys of the pharynx and esophagus revealed major differences between their patterns of catecholaminergic (CA) and serotonergic innervation. Whereas THli fibers and cell bodies were distributed throughout the foregut, 5HTli fibers were present in restricted plexi, and no 5HTli somata were detected. Double-labeling experiments in the periphery revealed THli neurons projecting toward the buccal ganglion via En(2). Other afferents received dense perisomatic serotonergic innervation. Finally, qualitative and quantitative differences were observed between the buccal motor programs (BMPs) produced by stimulation of the two En branches. These observations increase our understanding of aminergic contributions to the pregastric regulation of Aplysia feeding behaviors.

Localization of biogenic amines and neuropeptides in adrenal medullary cells of birds.

The present article reviews the immunohistochemical findings on the localization of biogenic amines and neuropeptides in adrenal medullary cells of birds. In the chicken, about 70% of medullary cells are adrenaline-containing cells and the rest of cells seem to be noradrenaline-containing cells. The ratio of adrenaline-cells to noradrenaline-cells extremely varies among avian species. Besides adrenaline and noradrenaline, medullary cells of birds contain many kinds of biogenic amines and neuropeptides: serotonin, galanin, cholecystokinin, somatostatin, enkephalin, neuropeptide tyrosine and atrial natriuretic peptide. The existence of these bioactive substances in medullary cells also exhibits interspecies heterogeneity. In the chicken, serotonin and galanin are contained in both adrenaline- and noradrenaline-cells of the adrenal gland. Cholecystokinin- and somatostatin-immunoreactivity is restricted to adrenaline-containing cells. Enkephalin-immunoreactivity is seen in both adrenaline- and noradrenaline-cells, but in about half of medullary cells. Neuropeptide tyrosine-immunoreactivity is found in the adrenal gland of the chick embryo and newly hatched chick, but not in the adult chicken. Serotonin and these neuropeptides may be selectively coreleased with adrenaline and/or noradrenaline from adrenal medullary cells of the chicken.

The pancreatic ductal system of the rat: cell diversity, ultrastructure, and innervation.

The morphological features and innervation of the pancreatic ductal epithelium of the rat was investigated. For the purposes of this study, pancreatic ducts were classified as either intercalated, intralobular, interlobular, or main. Epithelial cells of these different classes were classified as either principal or specialized. Principal cells make up the majority of epithelial cells in all classes of ducts. Ultrastructural analysis indicated that cytoplasmic vesicles, some containing amorphous material, were often seen in the apical portion of principal cells. Similarly, a common feature of these cells was the appearance of apical membrane projections containing various cytoplasmic organelles. These vesicles and apical membrane projections became larger as one progressed through the ductal system to the main duct. Junctional complexes contained well-developed tight junctions that, when analyzed by freeze-fracture analysis, were found to consist of three to five sealing strands in a parallel arrangement. Specialized cells could be morphologically divided into five categories: light cells, basal cells, goblet cells, endocrine cells, and brush cells. Light cells, which only differed from principal cells by their clear, lightly staining cytoplasm, were found in all classes of ducts. Basal cells, which were attached to the basement membrane of the ductal epithelium but did not extend to the lumen, were found in all classes of ducts except the intercalated ducts. Goblet cells and endocrine cells were observed in the main and interlobular ducts, while cells very similar in morphologic appearance to the brush cells of the lung were found restricted to the interlobular ducts. Localization of biogenic amines by histofluorescence indicated that adrenergic nerve fibers were associated with the main ducts and interlobular ducts. Histochemical localization of acetylcholinesterase activity indicated that cholinergic fibers were also associated with the main and interlobular ducts. These results indicate that in the rat, the pancreatic ductal system is composed of a number of cell types that are differentially distributed in the various classes of ducts, and pancreatic ducts are associated with adrenergic and cholinergic nerves.

Microspectrofluorometry in biogenic amine research

Microspectrofluorometry has played an important part in the development and understanding of fluorescence techniques for the demonstration of biogenic amines. This paper reviews briefly the techniques currently available for the characterization and localization of biogenic amines, and considers the basic design considerations applicable to the construction of a microspectrofluorometer, with special emphasis on the automated correction of spectral data. Spectral data for the commonly occurring biogenic amines dopamine, noradrenaline and 5-hydroxytryptamine have been summarized and the criteria applicable to the spectral analysis of the individual amines and their mixtures discussed. Discrepancies between spectral data derived from tissues and model systems are reviewed and emphasis is given to the importance of biochemical studies of amines prior to definitive microspectrofluorometric analysis. The conceptual basis of quantitative microspectrofluorometry is reviewed with a particular emphasis on the limitations of such studies. The analysis of terminal fields by scanning microspectrofluorometry and its application to the study of extracellular amine distribution is discussed.

X-Ray Analysis of Cytochemical Reaction Products in Synaptic Areas

Specific cytochemical reactions have been instrumental in the illucidation of compounds within tissues, whether these compounds are hormones, enzymes, or molecules, such as certain nerve transmitter agents. Many cytochemical reaction products depend upon some complex, which is an electron dense deposit. Several types of cytochemical procedures can be used to visualize agents related to synaptic transmission at the junctional complex. One method which has been used with considerable success has been the cytochemical localization of biogenic amines (BAs), i.e., norepinephrine (NE) and dopamine (DA). For the past few years, a chrome complex formed with certain BAs and glutaraldehyde has been utilized to localize BAs at the electron microscopic level and the specificity of the reaction has been verified biochemically.

The Localization of Biogenic Amines in the Echinopluteus

The distribution of biogenic amines in the young pluteus of Psammechinus miliaris Gmelin was examined by means of the histochemical fluorescence method of Falck and Hillarp. Two different systems where monoamines occur were detected. Catecholamines were mainly found in a presumably impulse propagating neuron-like system, while 5-HT (serotonin) was predominantly localized in the endoderm wall. The results are discussed in relation to the ontogeny and phylogeny of sea urchins.

Localization of biogenic amines and monoamine oxidase in the rabbit hippocampus

Comparison of the localization of monoamines and monoamine oxidase in the rabbit hippocampus shows that most pyramidal and all granular neurons contain no monoamines. Up to 1% of pyramidal and about 3% of polymorphic neurons are noradrenergic, and some of the latter are basket cells. Their terminals, containing both noradrenalin and monoamine oxidase, are in contact with the bodies and processes of the pyramidal and granular neurons. Single serotoninergic polymorphic neurons are found in sectors H1 and H2 of the cornu ammonis and in sector H5 of the fascia dentata of the hippocampus; they have few terminals. Noradrenergic afferents enter the cornu ammonis in the external bundle of the alveus and in the septal tract, which runs along the inner surface of the fimbria. Noradrenergic terminal plexuses surround the bodies of the pyramidal cells and are concentrated at the level of the apical dendrites of the pyramids and at the base of the granular neurons of the fascia dentata. Convergence of noradrenergic and serotoninergic terminals is found on some pyramidal, granular, and polymorphic neurons. The high concentration of serotonin in the hippocampus despite the minimal number of serotoninergic neurons can be explained by the large number of serotonin-containing stellate cells of nonneural nature. They are localized on groups of pyramidal neurons in sectors H1 and H2 and also on blood vessels. Individual variations are found in the number of serotonin-containing neurons in the hippocampus and in the number and distribution of serotonin-containing stellate cells.

New aspects of the localization of catecholamines in adrenergic neurons

Publisher Summary This chapter discusses new aspects of the localization of catecholamines in adrenergic neurons. The amine storing sites of adrenergic axons have been reinvestigated with an improved technique for the detection and localization of biogenic amines with the electron microscope. In addition to the well documented large and small dense core vesicles, the axons, especially their terminals, were revealed to contain a distinct third compartment, a tubular reticulum storing amines. On the other hand, the nerve fibers while containing much less amine storing vesicles per surface area compared to their terminals, show a similar proportion of large and small vesicles able to store norepinephrine (NE). Thus, small vesicles storing amines do not only exist in the nerve terminals but also in the whole axon, and presumably in the whole neuron. It is suggested that the three different compartments storing amines are formed in the cell body and probably migrate to the axonal terminals by means of neuroplasmic flow.