Showing papers by "Radboud University Nijmegen published in 1976"

Excitation-mediating and inhibition-mediating dopamine-receptors: a new concept towards a better understanding of electrophysiological, biochemical, pharmacological, functional and clinical data.

Abstract: A great number of earlier reported experimental data dealing with the role of dopamine in dopamine-loaded structures within the mammalian brain have raised questions concerning the concept of dopamine as an inhibitory agent acting on one type of receptor. A critical review of the anatomical, histochemical, electrophysiological, pharmacological and functional studies reveals that the dopamine-loaded structures are marked by an internal differentiation at various levels. It is attempted to demonstrate that this is due to a heterogeneous distribution of two distinct types of dopamine-receptors, each characterized by their own properties: DAe- and DAi-receptors. Furthermore, the experimental and clinical. implications are discussed in view of the hypothesis that balance between both types of receptors is essential for normal psychomotor functioning.

Circannual cycle in plasma testosterone levels in man.

Abstract: In a group of 15 healthy male subjects a statistically significant circannual cycle in plasma testosterone levels was assessed by sampling blood at 3-monthly intervals. Peak levels were found in summer and early autumn and a nadir in the winter and early spring.

Topological analysis of the brain stem of the frogs Rana esculenta and Rana catesbeiana.

Abstract: The ventricular sulcal pattern and the cytoarchitectonic organization of the brain stem of the frogs Rana esculenta and Rana catesbeiana have been studied in transversely cut, Nissl stained serial sections. Four longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans and the sulcus medianus superior could be distinguished in both species. A fifth longitudinal groove, the sulcus intermedius dorsalis, was found only in Rana esculenta. With the aid of the usual cytoarchitectonic criteria 25 cell masses have been delineated in Rana esculenta and 27 in Rana catesbeiana. These cell masses can be distributed over the following categories )numbers added in brackets for Rana catesbeiana, if different from those in Rana esculenta(: primary efferent or motor, 8: primary afferent or sensory, 4 )6(; “relay” centers, 7. Contrary to statements in the literature the reticular formation can be divided into six separate cell groups. The majority of the nuclei form part of the central gray, which constitutes a rather wide zone in anurans; three reticular nuclei lie partly within the stratum griseum and partly within the stratum album; six nuclei are entirely embedded in the stratum album. The morphological pattern of the cell masses and their relationship to the ventricular sulci were studied with the aid of a graphical reconstruction procedure termed topological analysis )cf. Nieuwenhuys, '74 and figs. 15, 16(. This analysis yielded the following results: The sulcus limitans extends throughout the rhombencephalon, dividing this brain part into a basal plate and an alar plate. The cell masses in the basal plate fit into two longitudinal zones, a medial area ventralis and a lateral area intermedioventralis. The area ventralis contains three somatic motor nuclei )IV, VI and XII( and the rhombencephalic medial reticular zone. The latter may be primarily considered as a somatic motor coordinating center. The area intermedioventralis contains the visceral motor nuclei of V, VII, IX and X. However, the basal plate also contains a number of non-motor centers, for example the superior olive. The alar plate contains visceral sensory, general somatic sensory and special somatic sensory centers. Two cell masses, the nucleus fasciculi solitarii and the nucleus visceralis secundarius, represent together a discontinuous visceral sensory zone. Both of these nuclei are situated immediately dorsal to the sulcus limitans. The special somatic sensory area, i.e., the area of termination of the eighth nerve, occupies a considerable part of the alar plate. This area comprises, apart from a large zone of diffuse gray, three distinct cell masses. The general somatic sensory nuclei, i.e., the nucleus tractus descendens and the nucleus princeps of V, constitute a zone which largely overlaps the nucleus fasciculi solitarii and one of the octavus nuclei. In the frogs investigated the cell masses in the midbrain do not exhibit a clear-cut morphological pattern. Functionally, however, the medial part of the tegmentum mesencephali may be considerd as the rostral extreme of the somatic motor area, whereas the lateral part of the tegmentum and the tectum are chiefly occupied by special somatic centers of primary and higher orders.

Descending pathways from the brain stem to the spinal cord in some reptiles. II. Course and site of termination.

Abstract: The course and termination of the pathways descending from the brain stem to the spinal cord have been studied by tracing the ensuing antero grade fiber degeneration, following appropriate lesions in the reptiles Testudo hermanni, Tupinambis nigropunctatus and Python reticulatus. In these reptiles the presence of interstitiospinal, vestibulospinal and reticulospinal pathways has been demonstrated. A crossed rubrospinal tract has been shown in the turtle and lizard, but could not be demonstrated in the Python. The presence of a tectospinal pathway of any importance could not be shown. However, the tectum mesencephali has been found to project profusely to the brain stem reticular formation. The interstitiospinal tract projects predominantly to the ipsilateral side of the spinal cord. The vestibulospinal projection, arising from the large-celled nucleus vestibularis ventrolateralis, comprises a large uncrossed and a small decussating component. The rubrospinal pathway terminates in a particular area of the spinal gray, i.e., the intermediate zone, whereas the interstitiospinal, reticulospinal and vestibulospinal tracts all terminate in the medial part of the ventral horn. It appeared that the classification of descending pathways as advocated in mammals by Kuypers ('64) into lateral and medial systems can be readily applied to reptiles. The lateral system terminates in the dorsal and lateral parts of the intermediate zone, the medial system predominantly in the dorsomedial part of the ventral horn. This classification renders it likely that the absence of a lateral focus of termination as well as the absence of a rubrospinal tract in the Python, is correlated to the absence of limbs. A comparison of experimental data concerning the systems descending from the brain stem to the spinal cord in amphibians, reptiles, birds and mammals suggests that these systems with regard to origin, course and termination have a basic pattern in common.

Desending pathways from the brain stem to the spinal cord in some reptiles. I. Origin

Abstract: In the present study the origin of the pathways descending from the brain stem to the spinal cord has been investigated in the reptiles Testudo hermanni, Pseudemys scripta elegans, Tupinambis nigropunctatus and Python reticulatus. These reptiles, using highly different types of progression, have been selected, because fundamental variations in the organization of the central motor apparatus are to be expected. The origin of the descending pathways has been demonstrated by recording the occurrence of retrograde cell changes following hemicordotomies and by searching for labeled cells following injection into the spinal cord of the enzyme horseradish peroxidase. In the reptiles studied the presence of interstitiospinal, vestibulospinal and reticulospinal pathways could be demonstrated. A crossed rubrospinal tract has been shown in the turtles and in the lizard, but could not be demonstrated in the Python. The presence of a direct tectospinal pathway could not be shown.

Topological analysis of the brain stem of the axolotl Ambystoma mexicanum.

Abstract: The ventricular sulcal pattern and the cellular structure of the brain stem of the axolotl Ambystoma mexicanum have been studied in transversely cut Nissl and Bodian stained serial sections. Six longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, the sulcus medianus superior and the sulcus lateralis mesencephali could be distinguished. A seventh groove, the sulcus isthmi, clearly deviates from the overall longitudinal pattern of the other sulci. Although most neuronal perikarya are contained within a diffuse periventricular gray, 19 cell masses could be delineated; seven of these are primary efferent or motor nuclei, four are primary afferent or sensory centers, four nuclei are considered as components of the reticular formation, and the remaining four cell masses can be interpreted as "relay" nuclei. In order to study the zonal pattern of the brain stem, this structure was subjected to a topological analysis (cf, Nieuwenhuys, '74 and fig. 13). This analysis yielded the following results. In the rhombencephalon the grisea are arranged in four longitudinal zones which, following Kuhlenbeck, have been termed area ventralis, area intermedioventralis, area intermediodorsalis and area dorsalis. Where present the sulcus intermedius ventralis, the sulcus limitans and the sulcus intermedius dorsalis mark the boundaries between these four morphological entities. The zonal areas in question coincide largely, but not entirely, with the so-called functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the nucleus fasciculi solitarii and the nucleus visceralis secundarius, two non-visceral sensory cell masses, namely the nucleus vestibularis magnocellularis and the nucleus cerebelli. The four morphological zones delineated in the rhombencephalon cannot be distinguished in the mesencephalon and it is of particular importance that the sulcus limitans does not extend into this part of the brain. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extreme of the somatic motor column, whereas the tectum primarily represents a somatic sensory correlation area.

Topological analysis of the brain stem of the sharks Squalus acanthias and Scyliorhinus canicula.

Abstract: The ventricular sulcal pattern and the cellular structure of the brain stem of the sharks Squalus acanthias and Scyliorhinus canicula have been studied in transversely cut Nissl, Kluver-Barrera and Bodian stained serial sections. Five longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis and the sulcus medianus superior could be distinguished in both species. In addition to these long, principal grooves, a number of shorter, accessory sulci appeared to be present. Although the neuronal perikarya in many places display a diffuse arrangement, with the aid of the usual cytoarchitectonic criteria 34 cell masses could be delineated in Squalus and 30 in Scyliorhinus. These cell masses can be distributed over the following categories )numbers added in brackets for Scyliorhinus, if different from those in Squalus(: primary efferent or motor, 10 )9(; primary afferent or sensory, 7: reticular formation, 5; “relay” centers, 9 )8(; nuclei of unknown relationships, 3 )1(. Seven of the cell masses found in Squalus and four of those found in Scyliorhinus have not been described before. The morphological pattern of the cell masses and their relationship to the ventricular sulci were studied with the aid of a graphical reconstruction procedure termed topological analysis )cf. Nieuwenhuys, '74, and figs. 24, 25(. This analysis yielded for both sharks the following results: A sulcus limitans extends from the spinal level to the pretrigeminal region. This sulcus divides the greater part of the rhombencephalon into a basal plate and an alar plate. In the basal plate the sulcus intermedius ventralis marks the boundary between an area ventralis and an area intermedioventralis. The area ventralis contains two somatic motor centers )i.e., the rostral end of the spinal motor column and the medial part of the nucleus of VI( and by far the greater portion of the rhombencephalic medial reticular formation. The latter may be primarily considered as a somatic motor coordinating center. The area intermedioventralis contains the visceral motor nuclei of X, IX, VII and V. However, the basal plate also harbours a number of non-motor centers, for example the inferior olive and the nucleus funiculi lateralis. In the caudal half of the rhombencephalon the sulcus intermedius dorsalis subdivides the alar plate into an area intermediodorsalis and an area dorsalis. The area intermediodorsalis is largely occupied by the common visceral sensory center of X, IX and VII; however, this area also contains the general somatic sensory nucleus descendens of V and the nucleus vestibularis magnocellularis. The area dorsalis is entirely occupied by two large lateral line nerve centers. The cell masses in the isthmus region and in the mesencephalon do not exhibit a clear-cut morphological pattern. Functionally, however, a number of centers in the medial part of the tegmentum mesencephali )nuclei of IV and III, nucleus of the f.l.m., nucleus ruber( may be considered as a rostral continuation of the rhombencephalic somatic motor area. Similarly, the nucleus of Edinger-Westphal represents the visceral motor zone at the midbrain level. The lateral part of the tegmentum mesencephali contains the nucleus of the torus semicircularis and the nucleus tegmentalis lateralis. It is suggested that these two nuclei together constitute a zone of somatic sensory relay centers.

Protein synthesis in salivary glands of Drosophila hydei after experimental gene induction.

Abstract: Several treatments, namely incubation at 37 degrees C, in the presence of arsenite, 2,4-dinitrophenol or vitamin B-6, or release from anaerobiosis induce the same set of puffs in the polythene chromosomes of salivary glands of Drosophila hydei. Analysis of changes in protein-synthetic patterns (as determined by radioautography of sodium dodecyl sulphate-gel electrophoretograms of extracts from [35S]methionine-labelled salivary glands) showed that concomitant with puff induction by these various treatments the same six strongly labelled polypeptide bands appeared. The amount of radioactive label in these peptides accounted for 25% of the total incorporation of [35S]methionine, except during incubation at 37 degrees C when it accounted for about 50%. The rate of synthesis of these peptides was maximal 1 h after the start of the puff-inducing treatment. The rate of decay of the rate of synthesis showed first-order kinetics both after removal of the puff-inducing stimulus or in the presence of actinomycin, with a half-life of approx. 4h.