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See detailInterplay among catecholamine systems: dopamine binds to alpha2-adrenergic receptors in birds and mammals.
Cornil, Charlotte ULg; Ball, Gregory F

in Journal of Comparative Neurology (The) (2008), 511(5), 610-27

Dopaminergic and adrenergic receptors are G-protein-coupled receptors considered to be different based on their pharmacology and signaling pathways. Some receptor subtypes that are members of one family ... [more ▼]

Dopaminergic and adrenergic receptors are G-protein-coupled receptors considered to be different based on their pharmacology and signaling pathways. Some receptor subtypes that are members of one family are actually closer in phylogenetic terms to some subtypes belonging to the other family, suggesting that the pharmacological specificity among these receptors from different families is not perfect. Indeed, evidence is accumulating that one amine can cross-talk with receptors belonging to the other system. However, most of these observations were collected in vitro using artificial cell models transfected with cloned receptors, so that the occurrence of this phenomenon in vivo as well as its distribution in the central nervous system is not known. In this study the pharmacological basis of possible in vivo interactions between dopamine and alpha(2)-adrenergic receptors was investigated in quail, zebra finches, and rats. Binding competitions showed that dopamine displaces the binding of the selective alpha(2)-adrenergic ligand, [(3)H]RX821002, in the brain of the three species with an affinity approximately 10-28-fold lower than that of norepinephrine. Dopamine also displaces with an affinity 3-fold lower than norepinephrine the binding of [(3)H]RX821002 to human alpha(h2A)-adrenergic receptors expressed in Sf9 cells. The anatomical distribution of this interaction was assessed in brain slices of quail and rat based on autoradiographic methods. Both norepinephrine and dopamine significantly displace [(3)H]RX821002 binding in all brain nuclei considered. Together, these data provide evidence for an interaction between the dopaminergic and noradrenergic systems in the vertebrate brain, albeit with species variations. [less ▲]

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See detailLocalization and Controls of Aromatase in the Quail Spinal Cord
Evrard, H.; Baillien, M.; Foidart, Agnès ULg et al

in Journal of Comparative Neurology (The) (2000), 423(4), 552-64

In adult male and female Japanese quail, aromatase-immunoreactive cells were identified in the spinal dorsal horns from the upper cervical segments to the lower caudal area. These immunoreactive cells are ... [more ▼]

In adult male and female Japanese quail, aromatase-immunoreactive cells were identified in the spinal dorsal horns from the upper cervical segments to the lower caudal area. These immunoreactive cells are located mostly in laminae I-III, with additional sparse cells being present in the medial part of lamina V and, at the cervical level exclusively, in lamina X around the central canal. Radioenzyme assays based on the measurement of tritiated water release confirmed the presence of substantial levels of aromatase activity throughout the rostrocaudal extent of the spinal cord. Contrary to what is observed in the brain, this enzyme activity and the number of aromatase-immunoreactive cells in five representative segments of the spinal cord are not different in sexually mature males or females and are not influenced in males by castration with or without testosterone treatment. The aromatase activity and the numbers of aromatase-immunoreactive cells per section are higher at the brachial and thoracic levels than in the cervical and lumbar segments. These experiments demonstrate for the first time the presence of local estrogen production in the spinal cord of a higher vertebrate. This production was localized in the sensory fields of the dorsal horn, where estrogen receptors have been identified previously in several avian and mammalian species, suggesting an implication of aromatase in the modulation of sensory (particularly nociceptive) processes. [less ▲]

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See detailImmunocytochemical localization of ionotropic glutamate receptors subunits in the adult quail forebrain
Cornil, Charlotte ULg; Foidart, Agnès ULg; Minet, Arlette ULg et al

in Journal of Comparative Neurology (The) (2000), 428

The excitatory amino acid glutamate is implicated in the central control of many neuroendocrine and behavioral processes. The ionotropic glutamate receptors are usually divided into the N-methyl-D ... [more ▼]

The excitatory amino acid glutamate is implicated in the central control of many neuroendocrine and behavioral processes. The ionotropic glutamate receptors are usually divided into the N-methyl-D-aspartate (NMDA) and non-NMDA (kainate and AMPA) subtypes. Subunits of these receptors have been cloned in a few mammalian species. Information available in birds is more limited. In quail, we recently demonstrated that glutamate agonists (kainate, AMPA, and NMDA) rapidly (within minutes) and reversibly decrease in vitro aromatase activity like several other manipulations affecting intracellular HCa21 pools. Aromatase catalyzes the conversion of androgens into estrogens which is a limiting step in the control by testosterone of many behavioral and physiologic processes. Therefore, glutamate could control estrogen production in the brain, but the anatomic substrate supporting this effect is poorly understood. In quail, aromatase is mainly localized in the preoptic-hypothalamic-limbic system. We visualized here the distribution of the major ionotropic glutamate receptors in quail by immunocytochemical methods by using commercial primary antibodies raised against rat glutamate receptor 1 and receptors 2-3 (GluR1, GluR2/3: AMPA subtype, Chemicon, CA), rat glutamate receptors 5-7 (GluR5-7: kainate subtype, Pharmingen, CA), and rat NMDA receptors (NMDAR1, Pharmingen, CA). Dense and specific signals were obtained with all antibodies. The four types of receptors are broadly distributed in the brain, and, in particular, immunoreactive cells are identified within the major aromatase cell groups located in the medial preoptic nucleus, ventromedial hypothalamus, nucleus striae terminalis, and nucleus taeniae. Dense specific populations of glutamate receptor immunoreactive cells are also present with a receptor subtype-specific distribution in broad areas of the telencephalon. The distribution of glutamate receptors, therefore, is consistent with the idea that these receptors could be located at the surface of aromatase-containing cells and mediate the rapid regulation of aromatase activity in a direct manner. [less ▲]

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See detailHyperthermic induction of the 27-kDa heat shock protein (Hsp27) in neuroglia and neurons of the rat central nervous system.
Krueger-Naug, A. M.; Hopkins, D. A.; Armstrong, J. N. et al

in Journal of Comparative Neurology (The) (2000), 428(3), 495-510

The 27-kDa heat shock protein (Hsp27) is constitutively expressed in many neurons of the brainstem and spinal cord, is strongly induced in glial cells in response to ischemia, seizures, or spreading ... [more ▼]

The 27-kDa heat shock protein (Hsp27) is constitutively expressed in many neurons of the brainstem and spinal cord, is strongly induced in glial cells in response to ischemia, seizures, or spreading depression, and is selectively induced in neurons after axotomy. Here, the expression of Hsp27 was examined in brains of adult rats from 1.5 hours to 6 days after brief hyperthermic stress (core body temperature of 42 degrees C for 15 minutes). Twenty-four hours following hyperthermia, Western blot analysis showed that Hsp27 was elevated in the cerebral cortex, hippocampus, cerebellum, and brainstem. Immunohistochemistry for Hsp27 revealed a time-dependent, but transient, increase in the level of Hsp27 immunoreactivity (Hsp27 IR) in neuroglia and neurons. Hsp27 IR was detected in astrocytes throughout the brain and in Bergmann glia of the cerebellum from 3 hours to 6 days following heat shock. Peak levels were apparent at 24 hours, gradually declining thereafter. In addition, increases in Hsp27 IR were detected in the ependyma and choroid plexus. Hyperthermia induced Hsp27 IR in neurons of the subfornical organ and the area postrema within 3 hours and reached a maximum by 24 hours with a return to control levels 4-6 days after hyperthermia. Specific populations of hypothalamic neurons also showed Hsp27 IR after hyperthermia. These results demonstrate that hyperthermia induces transient expression of Hsp27 in several types of neuroglia and specific populations of neurons. The pattern of induced Hsp27 IR suggests that some of the activated cells are involved in physiological responses related to body fluid homeostasis and temperature regulation. [less ▲]

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See detailAnatomical Relationships between Aromatase and Tyrosine Hydroxylase in the Quail Brain: Double-Label Immunocytochemical Studies
Balthazart, Jacques ULg; Foidart, Agnès ULg; Baillien, M. et al

in Journal of Comparative Neurology (The) (1998), 391(2), 214-26

The activation of male sexual behavior in Japanese quail (Coturnix japonica) requires the transformation of testosterone to 17beta-estradiol by the enzyme aromatase (estrogen synthetase). There are ... [more ▼]

The activation of male sexual behavior in Japanese quail (Coturnix japonica) requires the transformation of testosterone to 17beta-estradiol by the enzyme aromatase (estrogen synthetase). There are prominent sex differences in aromatase activity that may be regulated in part by sex differences in catecholaminergic activity. In this study, we investigate, with double-label immunocytochemistry methods, the anatomical relationship between the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) and aromatase (ARO) in the quail brain. The immunoreactivity observed for each antigen generally matched the previously described distribution. One exception is the observation that cells weakly labeled for aromatase were found widely distributed throughout the telencephalon. The presence of telencephalic aromatase was confirmed independently by radioenzymatic assays. There was an extensive overlap between the distribution of the two antigens in many brain areas. In all densely labeled aromatase-immunoreactive (ARO-ir) cell groups, including the preoptic medial nucleus, nucleus of the stria terminalis, mediobasal hypothalamus, and paleostriatum ventrale, ARO-ir cells were found in close association with TH-ir fibers. These TH-ir fibers often converged on an ARO-ir cell, and one or more TH-ir punctate structure(s) were found in close contact with nearly every densely labeled ARO-ir cell. In the telencephalon (mostly the neostriatum), all TH-ir fibers were found to be part of fiber groups that surrounded weakly immunoreactive aromatase cells. The few cells exhibiting an intracellular colocalization were detected in the anteroventral periventricular nucleus. These results are consistent with the hypothesis that catecholaminergic inputs regulate brain aromatase. [less ▲]

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See detailIdentification of Catecholaminergic Inputs to and Outputs from Aromatase-Containing Brain Areas of the Japanese Quail by Tract Tracing Combined with Tyrosine Hydroxylase Immunocytochemistry
Balthazart, Jacques ULg; Absil, Philippe ULg

in Journal of Comparative Neurology (The) (1997), 382(3), 401-28

In the quail brain, aromatase-immunoreactive (ARO-ir) neurons located in the medial preoptic nucleus (POM) and caudal paleostriatum ventrale/nucleus accumbens/nucleus striae terminalis complex (PVT/nAc ... [more ▼]

In the quail brain, aromatase-immunoreactive (ARO-ir) neurons located in the medial preoptic nucleus (POM) and caudal paleostriatum ventrale/nucleus accumbens/nucleus striae terminalis complex (PVT/nAc/nST) receive catecholaminergic inputs identified by the presence of tyrosine hydroxylase-immunoreactive (TH-ir) fibers and punctate structures. The origin of these inputs was analyzed by retrograde tracing with cholera toxin B subunit (CTB) or red latex fluospheres (RLF) combined with TH immunocytochemistry. CTB and RLF injected in the POM or PVT/nAc/nST were found in cells located in anatomically discrete areas in the telencephalon (hippocampus, septum, archistriatum), hypothalamus (many areas in periventricular position), thalamus, mesencephalon, and pons. In these last two regions, many retrogradely labeled cells were located in dopaminergic areas such as the retroruberal field (RRF), substantia nigra (SN), and area ventralis of Tsai (AVT) but also in noradrenergic cell groups such as the locus ceruleus and subceruleus. CTB tracing showed that most of these connections are bidirectional. Many retrogradely labeled cells contained TH-ir material. As a mean, 10-20% and 40-60% of the RLF-containing cells in the dopaminergic areas were TH-ir when RLF had been injected in the POM or PVT/nAc/nST, respectively. TH-ir cells projecting to the POM appeared to be mostly located in the periventricular hypothalamus and in AVT, whereas projections to the PVT/nAc/nST originated mainly in the SN (with significant contributions from the RRF and AVT). These data support the existence of functional relationships between aromatase and catecholamines. [less ▲]

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See detailConstitutive expression of the 27-kDa heat shock protein (Hsp27) in sensory and motor neurons of the rat nervous system.
Plumier, Jean-Christophe ULg; Hopkins, D. A.; Robertson, H. A. et al

in Journal of Comparative Neurology (The) (1997), 384(3), 409-28

In this study, the constitutive expression of the 27-kDa heat shock protein (Hsp27) in the adult rat central nervous system has been examined by immunohistochemistry and by two-dimensional gel Western ... [more ▼]

In this study, the constitutive expression of the 27-kDa heat shock protein (Hsp27) in the adult rat central nervous system has been examined by immunohistochemistry and by two-dimensional gel Western blot analysis. Hsp27 immunoreactivity was observed primarily in motoneurons of cranial nerve nuclei and spinal cord, and in primary sensory neurons and their central processes. Also, Hsp27 immunoreactivity was present in neurons of the arcuate nucleus and of the reticular formation. However, only a subset of these neurons was Hsp27-immunoreactive. Most general somatic efferent motoneurons of the hypoglossal nucleus and spinal motor columns and most special visceral efferent motoneurons of the cranial nerve nuclei were Hsp27-positive. In contrast, fewer general somatic efferent motoneurons for eye muscles were Hsp27-positive, and only a small proportion of general visceral efferent neurons, i.e., parasympathetic and sympathetic preganglionic neurons, were stained for Hsp27. Many pseudounipolar sensory neurons were Hsp27-immunoreactive, and the patterns of staining in central sensory nuclei suggested that specific subpopulations of sensory neurons contained Hsp27. The cellular distribution of Hsp27 was uniform throughout the cytoplasm, including the perikaryon, axon and dendrites, the latter often exhibiting varicosities or beading in distal processes. Western blot analyses revealed that at least three phosphorylated isoforms of Hsp27 were present in the spinal cord. These results suggest that constitutively expressed Hsp27 may be related to functional subpopulations of motoneurons and primary sensory neurons. [less ▲]

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See detailThe Catecholaminergic System of the Quail Brain: Immunocytochemical Studies of Dopamine Beta-Hydroxylase and Tyrosine Hydroxylase
Bailhache, T.; Balthazart, Jacques ULg

in Journal of Comparative Neurology (The) (1993), 329(2), 230-56

The distribution of dopamine beta-hydroxylase and tyrosine hydroxylase, two key enzymes in the biosynthesis of catecholamines, was investigated by immunocytochemistry in the brain of male and female ... [more ▼]

The distribution of dopamine beta-hydroxylase and tyrosine hydroxylase, two key enzymes in the biosynthesis of catecholamines, was investigated by immunocytochemistry in the brain of male and female Japanese quail. Cells or fibers showing dopamine beta-hydroxylase and tyrosine hydroxylase immunoreactivity were considered to be noradrenergic or adrenergic, while all structures showing only tyrosine hydroxylase immunoreactivity were tentatively considered to be dopaminergic. The major dopaminergic and noradrenergic cell groups that have been identified in the brain of mammals could be observed in the Japanese quail, with the exception of a tuberoinfundibular dopaminergic group. The dopamine beta-hydroxylase-immunoreactive cells were found exclusively in the pons (locus ceruleus and nucleus subceruleus ventralis) and in the medulla (area of the nucleus reticularis). The tyrosine hydroxylase-immunoreactive cells had a much wider distribution and extended from the preoptic area to the level of the medulla. They were, however, present in larger numbers in the area ventralis of Tsai and in the nucleus tegmenti pedunculo-pontinus, pars compacta, which respectively correspond to the ventral tegmental area and to the substantia nigra of mammals. A high density of dopamine beta-hydroxylase- and tyrosine hydroxylase-immunoreactive fibers and punctate structures was found in several steroid-sensitive brain regions that are implicated in the control of reproduction. In the preoptic area and in the region of the nucleus accumbens-nucleus stria terminalis, immunonegative perikarya were completely surrounded by immunoreactive fibers forming basket-like structures. Given that some of these cells contain the enzyme aromatase, these structures may represent the morphological substrate for a regulation of aromatase activity by catecholamines. The dopamine beta-hydroxylase-immunoreactive fibers were also present in a larger part of the preoptic area of females than in males. This sex difference in the noradrenergic innervation of the preoptic area presumably reflects the sex difference in norepinephrine content in this region. [less ▲]

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See detailImmunocytochemical Localization of Androgen Receptors in the Male Songbird and Quail Brain
Balthazart, Jacques ULg; Foidart, Agnès ULg; Wilson, E. M. et al

in Journal of Comparative Neurology (The) (1992), 317(4), 407-20

The distribution of androgen receptors was studied in the brain of the Japanese quail (Coturnix japonica), the zebra finch (Taeniopygia guttata), and the canary (Serinus canaria) by immunocytochemistry ... [more ▼]

The distribution of androgen receptors was studied in the brain of the Japanese quail (Coturnix japonica), the zebra finch (Taeniopygia guttata), and the canary (Serinus canaria) by immunocytochemistry with a polyclonal antibody (AR32) raised in rabbit against a synthetic peptide corresponding to a sequence located at the N-terminus of the androgen receptor molecule. In quail, androgen receptor-immunoreactive cells were observed in the nucleus intercollicularis and in various nuclei of the preoptic-hypothalamic complex, namely, the nucleus preopticus medialis, the ventral part of the nucleus anterior medialis hypothalami, the nucleus paraventricularis magnocellularis, the nucleus ventromedialis hypothalami, and the tuberal hypothalamus. In the two songbird species, labeled cells were also observed in various nuclei in the preoptic-hypothalamic region, in the nucleus taeniae, and in the nucleus intercollicularis. Additional androgen receptor-immunoreactive cells were present in the androgen-sensitive telencephalic nuclei that are part of the song control system. These immunoreactive cells filled and outlined the boundaries of the hyperstriatum ventrale, pars caudalis, nucleus magnocellularis neostriatalis anterioris (both in the lateral and medial subdivisions), and nucleus robustus archistriatalis. The immunoreactive material was primarily present in cell nuclei but a low level of immunoreactivity was also clearly detected in cytoplasm in some brain areas. These studies demonstrate, for the first time, that androgen receptors can be detected by immunocytochemistry in the avian brain and the results are in general agreement with the binding data obtained by autoradiography with tritiated dihydrotestosterone. Immunocytochemical methods offer several advantages over autoradiography and their use for the study of the androgen receptor will greatly facilitate the analysis of steroid-sensitive systems in the avian brain. [less ▲]

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See detailDynamic changes in the density of radial glial fibres of the developing murine cerebral wall: A quantitative immunohistochemical analysis
Gadisseux, Jean-François; Evrard, Phlippe; Misson, Jean-Paul ULg et al

in Journal of Comparative Neurology (The) (1992), 321

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See detailGlial process elongation and branching in the developing murine neocortex: A qualitative and quantitative immunohistochemical analysis
Takahashi, Takao; Misson, Jean-Paul ULg; Caviness, Verne S

in Journal of Comparative Neurology (The) (1990), 302

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See detailThe dendritic organization of the human spinal cord: the motoneurons.
Schoenen, Jean ULg

in Journal of Comparative Neurology (The) (1982), 211(3), 226-47

The dendritic organization of motoneurons was analyzed with the Golgi stain and a morphometric method in the immature and adult human spinal cord. Each motoneuronal column was found to be characterized by ... [more ▼]

The dendritic organization of motoneurons was analyzed with the Golgi stain and a morphometric method in the immature and adult human spinal cord. Each motoneuronal column was found to be characterized by a specific orientation of dendritic trees and by a distinct pattern of dendritic bundling. Ventromedial motoneurons have a pyramidal dendritic tree with numerous, short longitudinal branches and elongated dorsal branches. The latter form thick bundles oriented toward the ventral gray commissure. Longitudinal dendrites form a narrow-meshed dendritic plexus, containing abundant microbundles. Motoneurons of the ventromedial column have fewer primary dendrites and a lower ramification index than other motoneurons. Central motoneurons are predominantly oriented longitudinally. The meshes of the rostrocaudal dendritic plexus are looser and the microbundles are finer. Most transverse dendrites run laterally and participate in dendritic bundles which penetrate into the ventrolateral funiculus. The rostrocaudal dendritic domain of ventrolateral motoneurons is the largest dendritic domain of all spinal neurons. The longitudinal dendritic network contains fine microbundles and appears wide-meshed. Transverse dendrites form lateral or medial dendritic bundles depending upon the position of their perikaryon. Dorsolateral motoneurons differ from other motoneurons by their multipolar organization with a slight preponderance of dorsoventral dendritic spread. Rudimentary lateral dendrite bundles are restricted to marginal neurons. The longitudinal plexuses of motoneuronal dendrites and the verticotransverse dendrite bundles of the ventromedial column are well developed in the 26-28-week-old fetus. In contrast, the horizontotransverse dendrite bundles of central and ventrolateral motoneurons can only be recognized from 36 weeks on. The possible specific functions of the various types of dendrites bundles are examined and a laminar dendroarchitectonic schema of the human cord is proposed. [less ▲]

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