Biomedical subjects

A Dinopoulos

Publications and source records attributed to A Dinopoulos.

At least 37 records · Page 2Linked to original sources

PubMed1991

The development of ventral tegmental area (VTA) projections to the visual cortex of the rat.

The development of the ventral tegmental area (VTA) projections to the rat visual cortex was studied with the wheat germ agglutinin-horseradish peroxidase (WGA-HRP) retrograde tracing technique. Large injections of WGA-HRP in the visual cortex of newborn, early postnatal, and adult rats resulted in a substantial number of retrogradely labelled neurons in the VTA showing the same distribution pattern at all ages examined. Contrary to other reports, labelled cells were never found in the pars compacta of the substantia nigra but occasionally were seen in the contralateral VTA near the midline. These neurons showed a continuous growth from the day of birth to the end of the second postnatal week, when they acquired morphological features comparable to the adult; they subsequently showed a substantial decrease in soma size. The present results clearly demonstrate that there exists a substantial mesocortical projection to the rat visual cortex which arises exclusively from the VTA. This projection is already established at birth, but the neurons which give rise to it appear morphologically immature during the first two postnatal weeks.

Animals↗

PubMed1991

Immunohistochemical localization of aspartate in corticofugal pathways.

In the present study we used immunohistochemistry, with an antibody directed against aspartate (Asp), in conjunction with wheat germ agglutinin-horseradish peroxidase (WGA-HRP) histochemistry to examine the Asp-containing neurons in the motor and somatosensory cortices of the rat that project to the caudate/putamen or the pons. Injections of WGA-HRP in the caudate/putamen labelled cells in layer V of both cortical areas. In the motor cortex, retrogradely labelled neurons were distributed throughout layer V; 59% of these cells were also Asp-immunoreactive. In the somatosensory cortex labelled neurons were found mainly in layer Vb; 57% of these cells were double labelled. A similar percentage of cells were double labelled in this cortical area following WGA-HRP injections into the pontine nuclei. These observations taken together with previous findings (Exp. Neurol., 105 (1989) 36-44) suggest that nearly equal proportions of neurons that give rise to the corticostriatal and corticopontine pathways may use either Asp or glutamate (Glu) as putative neurotransmitters.

Animals↗

PubMed1989

The development of basal forebrain projections to the rat visual cortex.

The development of the basal forebrain projections to the visual cortex of the rat were studied using retrograde tracer techniques. Injections of wheat germ agglutinin-horseradish peroxidase placed in the visual cortex of newborn animals resulted in labelling of neurons throughout the basal forebrain nuclei. Although at this time the overall distribution of retrogradely labelled cells within the basal forebrain appeared similar to that seen in the adult, cells were smaller and weakly stained. It was only at the end of the second postnatal week that the somata of stained neurons showed sizes and staining intensity comparable to the adult. This precedes or coincides with the reported significant increases in cortical and basal forebrain ChAT activity and the first detection of ChAT-labelled fibres in this cortical area. These data suggest an important developmental point around the end of the second postnatal week that may correspond to the time when a significant number of cholinergic axons first appear within the visual cortex. They also suggest that the cholinergic projections to the visual cortex develop late in comparison with the thalamic and other subcortical afferents in this cortical area.

Aging↗

PubMed1989

Basal forebrain projections to the lower brain stem in the rat.

The projections of the magnocellular nuclei of the basal forebrain to the lower brain stem were studied using the WGA-HRP method. Of these nuclei, the nucleus of the vertical and the nucleus of the horizontal limb of the diagonal band of Broca, the magnocellular preoptic nucleus, and the substantia innominata were found to project bilaterally to the caudal midbrain, pons, and medulla. Labeled cells in the medial septal nucleus and in the nucleus basalis were found ipsilaterally only when injections stained the caudal part of the interpeduncular nucleus. The present findings together with other recent reports reveal a more extensive distribution of basal forebrain efferents than was previously thought.

Animals↗

PubMed1989

Neurochemical heterogeneity among corticofugal and callosal projections.

Biochemical, physiological, and anatomical studies over the past 30 years have firmly established glutamate (Glu) as the major neurotransmitter of those cortical neurons which give rise to corticofugal pathways. In the present study we utilized immunohistochemistry, with an antibody directed against Glu, in conjunction with wheat germ agglutinin-horseradish peroxidase (WGA-HRP) histochemistry to examine the Glu-containing neurons which give rise to corticofugal and callosal projections of the rat. Injections of WGA-HRP into the pons labeled cells in layer V of both visual and somatosensory cortices. WGA-HRP-labeled cells which also stained for Glu were large pyramids and in the visual cortex constituted approximately 42% of the total number of neurons which had effectively transported WGA-HRP, while the percentage was 56% in the somatosensory cortex. Following caudate/putamen injections, WGA-HRP-labeled cells were confined to layer V of the somatosensory and motor cortices. Of these cells, 40% in the somatosensory cortex and 53% in the motor cortex were also stained for Glu. Finally, after WGA-HRP injections in the visual cortex numerous WGA-HRP-positive neurons were found throughout layers II-VI around the boundaries between area 17 and areas 18 and 18a of the contralateral hemisphere. Here, 38% of these cells were also labeled for Glu, but this percentage was higher (49%) when layers II-III were considered alone. These findings show that Glu is not the neurotransmitter used overwhelmingly in corticofugal and callosal projections and that different proportions of neurons are Glu-immunoreactive in the systems examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Neuropeptide Y-like immunoreactive neurons in the hedgehog (Erinaceus europaeus) and the sheep (Ovis aries) brain.

The peroxidase-antiperoxidase immunohistochemical method has been used in order to investigate the distribution of neurons immunoreactive with antiserum against neuropeptide Y in the hedgehog and the sheep brain. Neuropeptide Y-immunoreactive bipolar and multipolar neurons, with a diameter ranging from 10-30 microns, were found in the following regions: cerebral cortex, striatum, Ammon's horn, gyrus dentatus, amygdala, anterior olfactory nucleus, nucleus accumbens, area along the medial forebrain bundle, arcuate nucleus of the hypothalamus and lateral reticular nucleus of both hedgehog and sheep brain. Furthermore, while neuropeptide Y-immunoreactive neurons were also found in the medial and lateral septal nucleus, interstitial nucleus of the stria terminalis, retrochiasmatic area, central gray substance of the midbrain, colliculus caudalis, and nucleus of the solitary tract of the sheep, respective regions of the hedgehog brain appeared to be devoid of immunoreactive perikarya. This distribution pattern is identical to that observed with antiserum against avian pancreatic polypeptide. The differences in the distribution of neuropeptide Y-immunoreactive neurons in the two species studied as well as between our results and those in other species are briefly discussed.

Animals↗

PubMed1988

Morphology of neurons in the basal forebrain nuclei of the rat: a Golgi study.

The neuronal cell types and their morphology in the nucleus basalis (NB), in the horizontal and vertical limbs of the diagonal band of Broca (NHL and NVL), and in the medial septal nucleus (MSN) were examined in Golgi-impregnated material. Cells appeared as multipolar or oligopolar and displayed a variable dendritic morphology; their somata varied considerably both in shape and size. The dendrites of most cells were restricted within nuclear boundaries, although occasionally neurons located near boundaries, particularly cells in NHL, extended dendritic arbors into neighboring areas. Axons were rarely seen, but when they were found they were generally not impregnated beyond the initial segment and displayed no apparent preferential direction. Three types of cells common to each of the 4 nuclear groups could be identified on the basis of soma shape and dendritic form. The first type included large multipolar neurons with triangular or polygonal perikarya and typically 3-5 dendrites emerging from the poles of each cell. These cells were especially numerous in NB, NHL, and NVL, but were much less frequent in MSN. The second type comprised medium-sized cells with round or oval somata and a small number, usually 2-3, of dendrites. They constituted a large percentage of the cell population in MSN, but were also encountered in NHL and NVL as well as in NB. The third type consisted of cells with fusiform or spindle-shaped somata with usually single dendrites emanating from each pole of the cell. A rare but distinct type of spindle-shaped neuron with dendrites bearing a rich complement of long and thin appendages was observed mainly in the ventral border of NHL. The present observations suggest that although the proportions and sizes of the 3 types of neurons vary between the 4 nuclei, neurons throughout the basal forebrain share common morphological characteristics.

Analysis of Variance↗

PubMed1988

Basal forebrain neurons project to the cortical mantle of the European hedgehog (Erinaceus europaeus).

The basal forebrain projections to the cortical mantle of the hedgehog were traced using the WGA-HRP method. The nuclei of the vertical and horizontal limbs of the diagonal band of Broca, the nucleus basalis and the substantia innominata were found to project to the ipsilateral frontal, parietal and occipital cortices. These projections, apparently cholinergic, were not topographically organized.

Animals↗

PubMed1988

Cortical and brain stem projections to the spinal cord of the hedgehog (Erinaceus europaeus). A horseradish peroxidase study.

Cortical and brain stem neurons projecting to the spinal cord in the hedgehog were studied by means of the horseradish peroxidase (HRP) tracing method. HRP injections were placed in the first cervical segments, in the cervical enlargement (C5-T3) and in the lumbar enlargement. Following injections in the first cervical segments and in the cervical enlargement labelled neurons were observed in the somatic motor and somatic sensory cortices, the paraventricular and the dorsomedial hypothalamic nucleus, the lateral hypothalamic area, the nuclei of field H of Forel, the red nucleus, the mesencephalic reticular formation, the deep layers of the superior colliculus, the Edinger-Westphal nucleus, the periaqueductal grey, the mesencephalic trigeminal nucleus, the loci coeruleus and subcoeruleus, the nuclei raphe dorsalis, centralis superior, raphe magnus, raphe pallidus, and raphe obscurus, the rhombencephalic reticular formation, the lateral, medial and caudal vestibular nuclei, the nucleus ambiguus, the nucleus of the solitary tract and the gracile nucleus. After HRP injections in the lumbar enlargement, labelled neurons were not found in the cortex, the dorsomedial hypothalamic nucleus, the nuclei of field H of Forel, the superior colliculus and the mesencephalic trigeminal nucleus. These results show that cortical and brain stem projections to the spinal cord are comparable to those described in other species.

Animals↗

PubMed1987

VIP- and CCK-like-immunoreactive neurons in the hedgehog (Erinaceus europaeus) and sheep (Ovis aries) brain.

The distribution pattern and the morphology of vasoactive intestinal polypeptide (VIP)- and cholecystokinin (CCK)-like-immunoreactive neurons were studied in the brain of the hedgehog and the sheep by means of the peroxidase-antiperoxidase immunocytochemical method. A total of 34 hedgehogs and 26 sheep of both sexes were used. Fourteen hedgehogs and 13 sheep received an intracerebroventricular injection of colchicine that enhanced the immunostaining and revealed "new" immunoreactive cell bodies. VIP-immunoreactive bipolar and multipolar neurons were observed in both species in the cerebral cortex, hippocampal formation, amygdaloid complex, hypothalamus, and central gray substance of the midbrain. CCK-immunoreactive bipolar, bitufted, and multipolar neurons displayed a broader distribution in both mammals than VIP neurons and were found in the cerebral cortex, the hippocampal formation, the amygdaloid complex, the hypothalamus, the mesencephalon, and the pons. In the cortex, in both the hedgehog and the sheep, VIP neurons were located in all layers but were concentrated in layers II and III, with the majority being typical bipolar. CCK neurons were more numerous in the superficial layers (I-III) but were found in the deep layers as well. They were bipolar, bitufted, or multipolar in morphology. From these neurons a small percentage, which were located almost exclusively in layers II and III of the visual cortex, exhibited also VIP immunoreactivity. Perikarya of such double-labeled cells were ovoid or round in shape with one or two main processes emanating from each pole of the cell body and oriented perpendicularly to the pia. The coexistence of the two peptides within individual neurons of the cortex has not been reported in other species and its physiological significance is discussed in relation to the GABAergic neurons of the cortex.

Animals↗

PubMed1987

Retinal projections in the hedgehog (Erinaceus europaeus). An autoradiographic and horseradish peroxidase study.

The retinal projections of the hedgehog were studied using tritiated leucine and horseradish peroxidase as orthograde tracers. In both series of experiments labeling was seen bilaterally in the suprachiasmatic nucleus, the dorsal and the ventral lateral geniculate nucleus, the superior colliculus, and the pretectal area and contralaterally in the terminal nuclei (dorsal, lateral and medial) of the accessory optic system. A retino-intergeniculate leaflet projection is described for the first time in this species, and its significance is discussed.

Animals↗

PubMed1986

Somatostatinlike immunoreactive neurons in the hedgehog (Erinaceus europaeus) and the sheep (Ovis aries) central nervous system.

The morphology and distribution of somatostatinlike immunoreactive perikarya in the central nervous system of the hedgehog and sheep have been studied by means of the peroxidase-antiperoxidase immunohistochemical method. Intracerebroventricular colchicine infusion not only enhanced the immunostaining but also revealed new immunoreactive cell bodies. In both hedgehog and sheep immunoreactive neurons of various forms, ranging from 12 to 28 microns in diameter, were observed in a number of homologous brain structures. However, some species-related differences were noticed. Thus, somatostatinlike immunoreactive neurons were found only in the hedgehog anterior olfactory nucleus, olfactory tubercle, nucleus accumbens, medial parabrachial nucleus, raphe nuclei of the medulla, and spinal trigeminal nucleus, whereas some somatostatin-positive neurons were observed in the locus coeruleus and the pontine reticular formation of the sheep only. Mapping of peptides in species like sheep and hedgehog, with basically different orientations of living behaviour, may contribute in strengthening or extending our views concerning the role of peptides in the central nervous system of mammals.

Amygdala↗

PubMed1986

Neurotensinlike immunoreactive neurons in the hedgehog (Erinaceus europaeus) and the sheep (Ovis aries) central nervous system.

Neurotensin-containing neurons in the hedgehog and sheep central nervous system were studied immunohistochemically. In both species, mapping of neurotensin neurons was achieved only after pretreatment with colchicine injected intracerebroventricularly 2 days prior to perfusion. Bipolar or multipolar neurotensin neurons, 10-30 micron in diameter, were observed in the following regions of the central nervous system of both species: medial amygdaloid nucleus, lateral septal nucleus, interstitial nucleus of the stria terminals, caudate nucleus, preoptic area, and hypothalamus. On the contrary, while immunoreactive neurons were found in the central amygdaloid nucleus, nucleus accumbens, nucleus of the diagonal band, subthalamus, superior central nucleus, dorsal raphe nucleus, central gray substance of the pons, and dorsal horn of the spinal cord of the hedgehog, respective regions of the sheep appeared to be devoid of immunoreactive perikarya. Also, in some regions, namely the hippocampal formation, the central gray substance of the midbrain, the locus coeruleus, and the nucleus of the solitary tract, neurotensin neurons were found exclusively in the latter species. The existence of these differences in the distribution pattern of neurotensin-immunoreactive neurons between the two species as well as between them and others already examined is briefly discussed.

Amygdala↗

PubMed1986

Thalamic projections to the posterior sylvian and posterior ectosylvian gyri of the sheep brain, revealed with the retrograde transport of horseradish peroxidase.

The auditory area of the sheep cerebral cortex was studied on the basis of its afferents from the medial geniculate nucleus, traced with the horseradish peroxidase retrograde transport method. The results show that the medial geniculate nucleus projects only to the anterior parts of the posterior ectosylvian gyrus and the posterior sylvian gyrus. A small area of the posterior ectosylvian gyrus receives afferents exclusively from the ventral part of the medial geniculate nucleus, while the anterior part of the posterior sylvian gyrus receives also afferents from the posterior nucleus of the thalamus and the pulvinar. In addition, it was found that the medial part of the medial geniculate nucleus projects in a sparse way to the auditory cortex. The middle part of the posterior ectosylvian gyrus receives afferents from the posterior nucleus of the thalamus, the suprageniculate nucleus and the pulvinar, while the posterior part of the posterior ectosylvian gyrus together with the posteriormost part of the posterior sylvian gyrus receive afferents from the pulvinar. Finally, the area located between the anterior and the posteriormost part of the posterior sylvian gyrus receives afferents from both the posterior nucleus of the thalamus and the pulvinar.

Animals↗

PubMed1986

Morphological characterization of cholinergic neurons in the horizontal limb of the diagonal band of Broca in the basal forebrain of the rat.

A monoclonal antibody against choline acetyltransferase (ChAT), the acetylcholine synthesizing enzyme, was used to identify cholinergic neurons in the nucleus of the horizontal limb of the diagonal band of Broca at the light and electron microscopic levels. ChAT-labelled somata were fusiform, triangular or round in shape and varied considerably in size. Depending on the type of the cell, one to four dendrites emerged from the soma, but an axon could rarely be seen. The nuclei of most cells were round or oval, showed invaginations and displayed prominent nucleoli. The karyoplasm of the larger fusiform and triangular neurons contained abundant organelles including parallel arrays of granular endoplasmic reticulum. The synaptic input to labelled perikarya and proximal dendrites was sparse. It consisted chiefly of asymmetrical synaptic contacts, sometimes with postjunctional densities, but a few symmetrical synapses were also noted. ChAT-positive axon terminals were not identified which suggests that axon collaterals are rare within the nucleus of the horizontal limb of the diagonal band of Broca.

Animals↗

PubMed1985

The coexistence of oxytocin and corticotropin-releasing factor in the hypothalamus: an immunocytochemical study in the rat, sheep and hedgehog.

The unlabeled antibody enzyme method has been applied on adjacent sections in order to investigate coexistence of oxytocin (OXY) and corticotropin-releasing factor (CRF) within individual neurons of the hypothalamic paraventricular nucleus of the colchicine-treated rat, sheep and hedgehog. Our results show that, although OXY and CRF immunoreactivities are both expressed by a number of cells in the rat and the sheep paraventricular nucleus, this is not the case for the hedgehog.

Animals↗

PubMed1985

Thalamic projections to motor, prefrontal, and somatosensory cortex in the sheep studied by means of the horseradish peroxidase retrograde transport method.

In this study the motor, prefrontal, and somatosensory areas of the sheep cerebral cortex were defined on the basis of their thalamic afferents traced with the horseradish peroxidase method. The motor area (areas 4 and 6) occupies the cruciate gyrus. It receives a substantial projection from the thalamic nuclei ventralis anterior, ventralis lateralis, medialis dorsalis, and centralis lateralis and a smaller one from the nuclei ventralis medialis, centralis medialis, paracentralis, lateralis dorsalis, lateralis posterior, centromedianus, parafascicularis, suprageniculatus, ventralis posterolateralis, and the midline nuclei. Area 4 receives afferents mainly from the nuclei ventralis anterior, ventralis lateralis, medialis dorsalis, and lateralis posterior, whereas area 6 receives afferents mainly from the nuclei ventralis anterior, medialis dorsalis, and lateralis posterior and fewer afferents from the nucleus ventralis medialis. The prefrontal area occupies the gyrus proreus and receives numerous afferents from the nucleus medialis dorsalis and fewer from the nuclei lateralis posterior and ventralis medialis. The area extending between the lateral fissure, the coronal sulcus, the presylvian sulcus, and the rostral branch of the lateral fissure is connected mainly with sensory thalamic nuclei. Thalamic afferents were found to emanate from the nuclei ventralis posteromedialis (its parvicellular part included), ventralis posterolateralis, ventralis medialis, paracentralis, lateralis posterior, medialis dorsalis, centromedianus, suprageniculatus, paraventricularis, the substantia nigra, and the ventral part of the lateral geniculate nucleus. The first somatosensory area (Johnson et al., '74, J. Comp. Neurol. 158:81-108) was found to extend between the coronal, the diagonal, and the anterior suprasylvian sulci and to receive afferents almost exclusively from the nucleus ventralis posteromedialis.

Animals↗

PubMedDate not supplied

Mucoepidermoid carcinoma of the bronchus.

Bronchoscopy in a 4.5-year-old girl with recurrent pneumonia showed an exophytic endobronchial mass. Biopsy disclosed microscopic and ultrastructural features of a low-grade mucoepidermoid carcinoma. Complete cure was accomplished by surgical removal of the tumor and right lower lobe.

Adolescent↗