Biomedical subjects
S L Palay
Publications and source records attributed to S L Palay.
A memoir in appreciation of Alan Peters on his sixty-fifth birthday.
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Professor David Bodian, M.D., Ph.D. (15 May 1910-18 September 1992).
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The founding of The Journal of Comparative Neurology.
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The general architecture of sensory neuroepithelia.
All neuroepithelia are sheets of cells lining an internal or external surface of the body and resting on a basement membrane. They consist of at least two kinds of cell, receptor cells and sustentacular (supporting) cells. Some contain undifferentiated precursor cells and senescent or degenerating cells. The potential for plasticity and regeneration in different sensory neuroepithelia varies widely according to their origins and structure in any individual animal and according to the species in which they occur. Four sensory neuroepithelia are described as examples of the range of construction, complexity, and life history.
Simultaneous demonstrations of neuropeptide Y gene expression and peptide storage in single neurons of the human brain.
A combination of in situ hybridization for neuropeptide Y mRNA that used a 32P-labeled complementary RNA probe and immunocytochemistry with polyclonal antibodies against neuropeptide Y were applied to human cortical brain samples to simultaneously localize neuropeptide Y and its mRNA. These two techniques allowed simultaneous identification of neuropeptide Y gene expression and peptide storage in single neurons of the human brain.
Localization of neuropeptide Y mRNA in neurons of human cerebral cortex by means of in situ hybridization with a complementary RNA probe.
The distribution of mRNA encoding neuropeptide Y (NPY) in neurons of the normal human cerebral cortex in surgical biopsy specimens and postmortem brain was studied by in situ hybridization techniques. A 32P-labeled complementary RNA (cRNA) probe was used on cryostat sections of 13 formaldehyde-fixed cortical biopsy specimens. Hybridization to NPY mRNA was found in all samples: after autoradiography, discrete deposits of silver granules were observed on neuronal cell bodies abundantly distributed in the deep layers of the cortex, particularly laminae IV and VI, and on smaller cell bodies in the white matter. The localization of the neurons hybridized for NPY mRNA was comparable to that of NPY-immunoreactive cells as shown in sections from the same tissue blocks immunostained by using NPY antibodies. The specificity of the in situ hybridization technique was confirmed by blot hybridization analysis of electrophoretically fractionated RNA. This study clearly demonstrated the consistent localization of NPY gene transcription and expression in normal mature human cortical neurons.
Galanin immunoreactivity in hypothalamic neurons: further evidence for multiple chemical messengers in the tuberomammillary nucleus.
By using a specific antibody against the 29 amino-acid peptide galanin (Gal) with light and electron microscopic immunocytochemistry, we have studied the distribution of Gal immunoreactivity in the posterior hypothalamic magnocellular neurons of the rat. In colchicine-treated rats, a large number of Gal-immunoreactive cells were identified within all subdivisions of the tuberomammillary nucleus. The majority of these cells are large multipolar or fusiform neurons, with long, sparsely branching dendrites. A small number project to the ventral hippocampus, as shown by experiments with the retrograde tracing of Fast Blue. Ultrastructural examination of the Gal-immunoreactive cells confirms their indentity as magnocellular neurons, with dense deposits of immunoreaction product, particularly in small ribosomal arrays and in large, dense-cored vesicles. Axosomatic synapses occur on these neurons. The axonal boutons synapse with asymmetric and symmetric junctions and contain small synaptic vesicles as well as numerous large, dense-cored vesicles, which display Gal immunoreactivity. Sequential staining of thin, alternate sections with antibodies against Gal and L-histidine decarboxylase (HDCase; EC 4.1.1.22) showed colocalization of Galand HDCase-immunoreactivities in a majority of tuberomammilary neurons. The finding of Gal immunoreactivity within histamine-producing neurons of the tuberomammillary nucleus adds to the multiplicity of potential neuronal messengers utilized by these cells.
Serotonin neurons on the ventral brain surface.
Serotonin neurons and fibers on the subpial surface of the ventral medulla oblongata in the rat are described by immunohistochemistry and autoradiography. The neurons are concentrated in the area encompassed by the origins of the abducens, hypoglossal, glossopharyngeal, and vagus nerves. The highest number of serotonin surface neurons appears along the median medullary fissure or basilar sulcus, where they may represent the most ventral extensions of the raphe pallidus group. As these cells lie on the surface of the brain, they could be directly affected by alterations in the chemical composition of the cerebrospinal fluid and, depending on their connections, could influence important medullary functions.
Distribution of tyrosine-hydroxylase-immunoreactive neurons in the hypothalamus of rats.
The distribution and morphology of cells containing tyrosine hydroxylase (TH) immunoreactivity in the hypothalamus of rats were studied by using a modified immunoperoxidase technique. The TH cell system is more complexly organized than was previously thought. On the basis of their clustering patterns, hypothalamic TH neurons could be subdivided into two groups: dorsal and ventral. The ventral group consists of a prominent aggregate of cells located in the caudal part of the arcuate nucleus. From here, cells extend around the caudal part of the ventromedial and dorsomedial nuclei and the base of the diencephalon. Tyrosine hydroxylase-positive cells are present throughout the arcuate nucleus, except in its ventromedial part. Anteriorly, immunoreactive cells appear in the suprachiasmatic and supraoptic nuclei, in the retrochiasmatic area, and in the ventral part of the anterior hypothalamic nucleus. The dorsal group has its main concentration of cells in the medial part of the zona incerta, from which two clusters of cells, one medial and one lateral, extend rostralward. The medial group comprises cells in the medial part of the dorsomedial, paraventricular, and anterior hypothalamic nuclei. These cells adjoin the periventricular cells. The lateral group of cells emanating from the zona incerta occupies the lateral part of the dorsomedial and anterior hypothalamic nuclei and the dorsal hypothalamic area. The dorsal and ventral TH cell groups are in continuity medially in the periventricular layer, and laterally through the cells that surround the ventromedial nucleus. Although the cells vary widely in size, shape, and dendritic arborization pattern, there are two main cell types. Small (21 X 11 microns), round to fusiform cells, with two or three dendrites arborizing simply, were frequently seen in the arcuate, suprachiasmatic, periventricular, supramammillary nuclei and at the borders of the ventromedial nucleus. The other cell type is larger (40 X 15 microns) and multipolar, with three to five frequently branching dendrites. The dendritic field is large and the cells are intensely TH-immunoreactive. Although the larger cells occur occasionally in every hypothalamic nucleus, their principal locations are in the dorsal parts of the dorsomedial, posterior hypothalamic nuclei and the dorsal and lateral parts of the zona incerta, and in the areas dorsal and medial to the mammillothalamic tract at caudal hypothalamic levels. In this paper we give a detailed description of TH-immunoreactive fibers and terminals in the hypothalamus and a comparison with previous studies of catecholamine cells in the hypothalamus.
Sagittal cerebellar microbands of taurine neurons: immunocytochemical demonstration by using antibodies against the taurine-synthesizing enzyme cysteine sulfinic acid decarboxylase.
Taurine neurons in the cerebellum of rabbit, rat, and mouse were localized at the light microscope level by using polyclonal antibodies against cysteine sulfinic acid decarboxylase (CSADCase; EC 4.1.1.29), the enzyme responsible for the conversion of cysteine sulfinic acid to hypotaurine and of cysteic acid to taurine. The indirect peroxidase-antiperoxidase method was used on Vibratome sections and on serial sections of paraffin-embedded tissue. Intensification of CSADCase immunoreactivity was achieved by pretreatment of the animal with L-cysteine or L-cysteic acid intravenously 1-2 hr prior to perfusion. A combination of L-cysteic acid and demecolcine, which retards axoplasmic flow, was most effective in maximizing CSADCase immunoreactivity. Although these treatments intensified immunoreactivity in neurons, no more cells were reactive than in untreated controls. L-Glutamic acid did not increase CSADCase immunoreactivity but did increase immunoreactivity with antibodies against L-glutamic acid decarboxylase (GAD; EC 4.1.1.15), the synthetic enzyme for gamma-aminobutyric acid. Specificity was established by negative results obtained with various control incubations including the use of CSADCase antiserum preabsorbed with the antigen. Taurine neurons of the cerebellar cortex are arranged in sagittal microbands, defined by intensely CSADCase-reactive Purkinje neurons and their axons and dendrites, together with stellate, basket, and Golgi cells and their processes. In the vermis there is a narrow midline band, flanked laterally by three wider bands on either side, each separated from the next by an unreactive zone. Although the zonal borders are sharp, the interzonal areas contain some CSADCase-immunoreactive axons but no cell bodies. The seven vermal bands are best observed in the anterior lobe. Others exist in the lateral hemispheres. The paraflocculus and flocculus contain numerous intensely immunoreactive neurons, and banding is difficult to discern. Lobule X of the vermis is also heavily endowed with taurine neurons. Numerous large and medium-sized deep cerebellar and vestibular nuclei are also immunoreactive. These observations indicate that cerebellar neurons are chemically heterogeneous but that neurons of similar chemical signature in the cerebellar cortex are organized into sagittal microbands. This corroborates our earlier evidence that Purkinje cells containing motilin and those containing both motilin and gamma-aminobutyric acid are also arranged in vermal sagittal microbands. The midline vermal band contains Purkinje neurons with multiple neuroactive substances-taurine, gamma-aminobutyric acid, and motilin. It remains to be determined how this chemical zonation in the cerebellar cortex relates to the banded afferent innervation from spinal, vestibular, reticular, and olivary sources.
Synthesizing enzymes for four neuroactive substances in motor neurons and neuromuscular junctions: light and electron microscopic immunocytochemistry.
Immunocytochemical evidence is presented for the existence of choline acetyltransferase (ChoAcTase), cysteine sulfinic acid decarboxylase (CSADCase), tyrosine hydroxylase (TyrOHase), and glutamic acid decarboxylase (GluDCase) in large motor neurons of the hypoglossal nucleus and the spinal cord and in nerve terminals of motor end plates in tongue and skeletal muscle of five mammalian species, including man. These enzymes, which are responsible for the synthesis of acetylcholine (AcCho), taurine, dopamine, and gamma-aminobutyrate (GABA), respectively, were detected by immunocytochemical studies with monoclonal or polyclonal antibodies raised against the enzymes. Electron microscopy of the neuromuscular junctions showed that the immunoreactivity in each case was confined to the cytoplasmic matrix of presynaptic nerve terminals. Immunoreactivity obtained for each enzyme antibody varied with the species. It was highest in fresh, unfixed muscle and lowest in aldehyde-fixed specimens. Negative controls were obtained with preimmune sera and antisera preabsorbed with pure ChoAcTase, CSADCase, or GluDCase antigen. Double-labeling studies with ChoAcTase antibodies and acetylcholinesterase (AcChoEase) antibodies, AcChoEase enzyme activity, or alpha-bungarotoxin binding indicated that ChoAcTase, AcChoEase, and AcCho receptors were colocalized at the same end plates.
Coexistence in human and primate neuromuscular junctions of enzymes synthesizing acetylcholine, catecholamine, taurine, and gamma-aminobutyric acid.
Coexistence of neurotransmitter-synthesizing enzymes choline acetyltransferase, cysteine sulfinic acid decarboxylase, tyrosine hydroxylase, and L-glutamic acid decarboxylase was demonstrated at human and primate neuromuscular junctions with specific antibodies directed against these enzymes. Motor end plates were identified in unfixed cryostat sections by standard cholinergic markers for acetylcholinesterase and the acetylcholine receptor. Each of the four transmitter-synthesizing enzymes was localized at end plates displaying these markers. The presence of any two of the four enzymes at a given end plate was established by (i) showing immunoreaction for one enzyme followed by elution and demonstration of immunoreaction for a second enzyme, and (ii) paired immunofluorescence with simultaneous demonstration of one enzyme with a rhodamine-labeled second antibody and of the other enzyme with a fluorescein-labeled second antibody. These findings imply that motor nerve terminals have the capacity for synthesizing not only acetylcholine but also taurine, catecholamines, and gamma-aminobutyric acid. These substances, in turn, may participate in the normal regulation of nerve-muscle interaction or be significant in specific disorders involving the motor unit.
The nucleus paragigantocellularis lateralis in the rat. Conformation and cytology.
The nucleus paragigantocellularis lateralis (PGCL) is located in the ventral portion of the rostral medulla. Serial sections of the rat brainstem were examined in the three cardinal planes and the boundaries of the PGCL were determined. In order to visualize the shape and extent of the nucleus, a three-dimensional reconstruction of the PGCL was made from a series of coronal sections. Measurements of neuronal areas, lengths, and widths indicate that a number of neuronal types are present. Small neurons measure less than 150 micron2 and large neurons greater than 250 micron2. Some neuronal types are distributed preferentially throughout the PGCL, and on this basis the nucleus may be divided into caudal and rostral subgroups. Most large neurons (greater than 250 micron2) are found in the caudal portion. Certain neurons contain intranuclear rods, and these neurons are often disposed in small groups, especially common the caudal PGCL. Two morphologically distinct neuronal types incorporate 3H-serotonin when this marker is infused into the ventricular system; the other neurons not marked by this method probably contain other, different transmitters. On the basis of neuronal measurements and staining qualities, it is ascertained that the PGCL is a parvocellular reticular nucleus characterized by many neuronal types.
The nucleus paragigantocellularis lateralis in the rat. Demonstration of afferents by the retrograde transport of horseradish peroxidase.
Injections of horseradish peroxidase (HRP) were placed in the middle or caudal portion of the nucleus paragigantocellularis lateralis (PGCL) and 24 h later the entire spinal cord and brain were processed and examined for labeled neurons. Spinal afferents arise from all levels of the cord. Rexed's lamination scheme was adapted to the spinal cord of the rat and labelled neurons were localized to laminae IV, V, VII, VIII and X mainly on the side contralateral to the injection. At cervical levels, labeled neurons were consistently found bilaterally. The medial reticular nuclei of the medulla and pons contained HRP-labelled perikarya, which were concentrated most heavily in the nuclei reticularis medullae oblongatae ventralis, gigantocellularis, and pontis caudalis predominantly ipsilateral to the injection. The medial vestibular nucleus was consistently labeled. HRP-labeled perikarya were found bilaterally within the commissural portion and in the medial part of the nucleus of the solitary tract on the side of the injection. The rostral portion of the PGCL receives afferents from some secondary auditory nuclei: the ipsilateral inferior colliculus and the posterior ventral cochlear nucleus bilaterally. Thus, the rostral PGCL may be involved in auditory feedback loops. The caudal raphe nuclei are a major source of afferents to the caudal PGCL. The lateral hypothalamic area, paraventricular nucleus, and zona incerta also contain labeled neurons when injections are centered in the caudal portion of the nucleus.
Chemical heterogeneity in cerebellar Purkinje cells: existence and coexistence of glutamic acid decarboxylase-like and motilin-like immunoreactivities.
Purkinje neurons of the cerebellar cortex from a chemically and morphologically heterogeneous population containing some members that have gamma-aminobutyric acid (GABA), others that have immunoreactivity for motilin, and a small number that have both. The remaining 30-40% of all Purkinje cells have neither of these two neuroactive substances, leaving possibilities for other transmitter candidates. The evidence was compiled from double-staining immunocytochemical procedures performed on single sections of the cerebellum and brain stem in rat, mouse, and monkey. Two polyclonal antibodies were applied in succession, one directed against the midregion and COOH terminus of the 22-amino acid polypeptide motilin and the other against glutamic acid decarboxylase (glutamate decarboxylase; L-glutamate 1-carboxy-lyase, EC 4.1.1.15), the rate-limiting enzyme in the synthesis of the neurotransmitter GABA. The staining combinations employed the immunoperoxidase method, with different chromogens for distinguishing the motilin-like immunoreactivity from glutamic acid decarboxylase immunoreactivity by different colors, or the immunoperoxidase method for one antiserum and immunofluorescence for the other. The locations of both motilin and GABA cell types were mapped. The recognition of motilin in Purkinje cells calls for experimental definition of the role of this substance in the cerebellum and for reevaluation of the roles of Purkinje cells and of GABA in cerebellar function. The significant motilin representation in the flocculus, paraflocculus, and vermis suggests that it may be the Purkinje cell mediative chemical in the vestibular parts of the cerebellum. However, the presence of GABA as well in the same regions indicates that the chemical preference may be at least bimodal.
Hyperinnervation of arrested granule cells produced by the transplantation of monoamine-containing neurons into the fourth ventricle of rat.
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Autoradiographic experiments to examine uptake, anterograde and retrograde transport of tritiated serotonin in the mammalian brain.
In an attempt to define the potential application of neurotransmitter-specific transport as a method of tracing fiber connections, we have examined the uptake and subsequent ortho- and retrograde transport of tritium-labeled serotonin (3H-5HT) in the cerebellum-raphe pallidus system. Injection of various concentrations of 3H-5HT followed by different post-injection survival times revealed different labeling patterns in the injected sites and different patterns of transport. The most striking feature is that nonseroitonin neurons as well as serotonin cells were able to take up and transport the tritium label in both otho- and retrograde fashion. The non-sertonin-specific nature of this uptake and transport is more obvious at higher concentrations of 3H-5HT (more than 9 X 10(-5) M), with longer survival times and following pretreatment with monoamine oxidase inhibitors. At a concentration of 9 X 10(-6) M 3H-5HT, only specific uptake seems to take place as evidenced by label in known serotinin cells and fiber systems; however, it was impossible to detect by autoradiography any ortho- or retrograde transport at this low concentration. Non-specific uptake and transport were observed following injection into the vestibular nuclei and oculomotor complex. This suggests that non-specific uptake and the transport of 3H-5HT or metabolites may also occur in other regions of the central nervous system.