Effect of β Adrenoreceptor Blocker Propranolol during Reflex Renal Dystrophy Induced by Sciatic Nerve Cutting

We present the data on the functional status of the mineralocorticoid receptor system in the rat kidney in the course of renal reflex dystrophy induced by sciatic nerve cutting against the background of both renal denervation and injections of propranolol, a -adrenoreceptor blocker. According to the state of renal mineralocorticoid receptors, the simultaneous block of both neural and humoral pathological stimuli coming to the kidney after the nerve injury prevented cytochemical changes in the organ more effectively than the block of neural transmission alone. We propose that both the central neural transmission and humoral mechanisms control the activity of the molecular structures responsible for aldosterone reception in the cells of renal tubules.     

On the Role of β-Adrenoreceptors in Mechanisms Underlying Neurogenic Dystrophies

Sciatic nerve damage led to a defective functioning of the renal mineralocorticoid receptors due to the disturbed neurotrophic supply of this organ: the reception of distorted nervous stimuli. The pharmacological blockade of both the neurotransmitter and the humoral pathways of the pathological stimuli from the damaged nerve to the kidney prevented the development of trophic disturbances as tested by the state of the renal mineralocorticoid receptor system. At the same time, the pharmacological stimulation of the sympathetic nervous system leads to an even more defective aldosterone reception by the kidney. Propranolol exerted an antidystrophic effect in the case of local damages of the nervous system and, thereby, prevented the development of neurogenic dystrophies.     

Sodium reabsorption and the aldosterone receptors in the cells of the kidney tubules in a dynamic disorder of the trophic function of the nervous system]

The results are presented of investigations on determining the functional state of mineralocorticoid receptor apparatus in rat kidney at diverse stages of the reflex renal dystrophy per se and that against the background of renal denervation along with propranolol injections produced at different terms following the disturbance of nervous system trophic function. It was shown that simultaneous blockade of neuroconductory and humoral pathways of pathological stimulus transmission from central end of cut ischiatic nerve to the kidney prevents the development of trophic disturbances in the organ as tested by the state of mineralocorticoid receptors, to a more extent than the blockade of neuroconductory pathway only. The activity of molecular structures which determine the mineralocorticoid reception in cells of renal tubules seems to be controlled both by central neuroconductory and humoral mechanisms.     

A new sensory organ in “primitive” molluscs (Polyplacophora: Lepidopleurida), and its context in the nervous system of chitons

Introduction

Chitons (Polyplacophora) are molluscs considered to have a simple nervous system without cephalisation. The position of the class within Mollusca is the topic of extensive debate and neuroanatomical characters can provide new sources of phylogenetic data as well as insights into the fundamental biology of the organisms. We report a new discrete anterior sensory structure in chitons, occurring throughout Lepidopleurida, the order of living chitons that retains plesiomorphic characteristics.

Results

The novel “Schwabe organ” is clearly visible on living animals as a pair of streaks of brown or purplish pigment on the roof of the pallial cavity, lateral to or partly covered by the mouth lappets. We describe the histology and ultrastructure of the anterior nervous system, including the Schwabe organ, in two lepidopleuran chitons using light and electron microscopy. The oesophageal nerve ring is greatly enlarged and displays ganglionic structure, with the neuropil surrounded by neural somata. The Schwabe organ is innervated by the lateral nerve cord, and dense bundles of nerve fibres running through the Schwabe organ epithelium are frequently surrounded by the pigment granules which characterise the organ. Basal cells projecting to the epithelial surface and cells bearing a large number of ciliary structures may be indicative of sensory function. The Schwabe organ is present in all genera within Lepidopleurida (and absent throughout Chitonida) and represents a novel anatomical synapomorphy of the clade.

Conclusions

The Schwabe organ is a pigmented sensory organ, found on the ventral surface of deep-sea and shallow water chitons; although its anatomy is well understood, its function remains unknown. The anterior commissure of the chiton oesophagial nerve ring can be considered a brain. Our thorough review of the chiton central nervous system, and particularly the sensory organs of the pallial cavity, provides a context to interpret neuroanatomical homology and assess this new sense organ.     

Immunohistochemical identification of supportive cell types in the enteric nervous system of the rat colon and rectum

Summary The non-neuronal, supportive cells of the enteric nerve plexus were investigated in the colon and rectum of adult and developing rats by means of immunohistochemistry, utilizing antisera against GFA protein and S-100 protein. Immunoreactivity to GFA protein was almost exclusively found in cells associated with the myenteric plexus and a small number of cells within the submucous ganglia. On the other hand, the use of S-100 protein antiserum resulted in the visualization of all supportive elements in the enteric nervous system. However, two types of supportive cells could be tentatively differentiated in the enteric nerve plexus during the second week of postnatal development, using GFA protein and S-100 protein antisera; GFA protein-positive cells were clearly discernible from S-100 protein-positive cells in terms of both the morphological profiles and immunohistochemical properties. It was assumed that at least two different types of supportive cells are contained in the enteric nerve plexus. We suggest that in the enteric nervous system the terms glial cells and Schwann cells should be employed to designate the supportive cells containing GFA and S-100 proteins, and cells containing S-100 protein, respectively. We discuss the possibility that glial cells are associated with the parasympathetic preganglionic fibres directly derived from the central nervous system, while Schwann cells originate from the neural crest.     

The antidystrophic effect of the action of beta-adrenoblockaders in local damage to the nervous system]

It has been established that the lesion of the sciatic nerve, accompanied by a disturbance of normal neurotrophic provision of a kidney as a result of coming to the organ of the perverted nervous stimuli (by the neuro-conductive path through sympathetic nerves and by participation of the hypothalamus--hypophysis--peripheral glands system), leads to disturbance of functioning of mineral-corticoid receptors of kidneys. It has been also established that simultaneous pharmacological blockade of neuro-conductive and humoral pathways of transmission to the kidney of pathological stimuli from the central stump of the cut sciatic nerve prevents the development of trophic organ disturbances, tested by the state of the kidney mineral-corticoid receptor apparatus, while pharmacological stimulation of sympathetic nervous system leads to the greater disturbance of aldosterone reception by the cells of kidney channels. A valid conclusion can be made that propranolol is a substance, which may weaken possible non-adequate reactions of peripheral tissues to the action of physiologically active substances during the development of the consequences of the lesion of the nervous system and thus to prevent the development of neurogenic dystrophies.     

Changes in physiological properties of frog taste cells following denervation

The structure of the taste organ and the physiological propertiesof the taste cell of the bullfrog (Rana catesbeiana) after theglossopharyngeal nerve transection were investigated. The frogtaste organ is composed of taste, supporting and basal cells.As nerve terminals within the taste organ degenerated, nerveresponses to mechanical, chemical and electrical stimuli graduallydeclined and finally ceased in 7 days during the summer and15 days during the winter. However, the taste cells still hadresting potentials and responded to four basic taste stimuliby generating receptor potentials with the various lengths ofduration, even 140 days after denervation. The glossopharyngealnerve transection affected the magnitude of resting potentialssignificantly. However, the taste, supporting and basal cellsmaintained their normal structures 140 days after surgery. Itis concluded, therefore, that neural dependency of the frogtaste organ is not as great as that in mammals.     

Photoreceptor-like outer segments in the pineal organ of the lovebird,Uroloncha domestica (Aves: Passeriformes)

Summary In the pineal organ of the lovebird, Uroloncha domestica, bulbous, cup-shaped and elongated outer segments of photoreceptor-like pinealocytes are demonstrated by scanning electron microscopy. These scarce outer segments, 4–11 m in length, extend into the pineal lumen. The present structural observations speak in favor of photosensitive pinealocytes in the pineal organ of Uroloncha domestica. The relation of the photoreceptor-like pinealocytes to acetylcholinesterase-positive nerve cells and a nervous connection between the pineal and the brain indicate that the pineal organ of this passeriform species may be the site of neuroendocrine and photoreceptive functions.Supported by a fellowship from the Japan Society for the Promotion of Science to M. UeckSupported by a grant from the Ministry of Education of Japan to K. Wake and by a grant of the Deutsche Forschungsgemeinschaft to M. Ueck     

Postnatal development of the intrinsic nervous system in the circumvallate papilla-vonEbner gland complex

We have studied the postnatal development of the intrinsic nervous system in the circumvallate papilla–vonEbner gland complex using NADPH-diaphorase cytochemistry, immunocytochemistry (for nitric oxide synthase-1 and -internexin) and electron microscopy. In rats sacrificed in their first day post partum (1p.p.), only isolated NADPH-diaphorase positive neurons were visible in the organ. At 2p.p., a small group of neurons was visible at the base of the papillae and positive neurons formed short chains close to the developing glandular tubules. In the following days, the NADPH-diapharase positive cells increased in number and nerve fibres were associated to small ganglia located at the base of the papilla or in the gland. After the first week of extrauterine life, the intrinsic nervous system was similar to the intrinsic system of adult animals. An immunocytochemical positivity for nitric oxide synthase-1 appeared at 4p.p. in neurons located in the gland and at 7p.p. in cells located at the base of the papilla. Immunocytochemical staining for -internexin showed that at 1p.p. developing nerve fibres were present in the connective tissue of the tongue's muscle layer. At 2–3p.p., developing nerve fibres were also present at the bases and in the core of the papilla. In the following days, the positivity for -internexin was reduced and one week after birth was virtually absent. Ultrastructural examination revealed that since 1p.p. isolated neurons can be found at the base of the papilla. In conclusion, the intrinsic nervous system originates from neurons present in the organ at the birth which, in the first days, undergo a biochemical and morphological maturation while the nerve fibres rapidly grow. These findings support the hypothesis that the intrinsic nervous system of the circumvallate papilla has a role in the maturation of the vonEbner gland.     

Pathways mediating abdominal phasic flexor muscle activity in crayfish with chronically cut nerve cords

1. Nerve cord transection abolishes the ability of crayfish (Procambarus clarkii) to produce tailflips in response to gradually applied tactile or proprioceptive stimulation of the abdomen, but this ability eventually returns. To determine the time-course of this return and to analyze its underlying neural pathways, we made behavioral observations, electromyographic recordings from abdominal phasic flexor muscles, and intracellular recordings from motoneurons in crayfish with cord lesions between the thorax and the abdomen.
2. Abdominal stimulation activated the phasic flexor muscles in the rostral 5 abdominal segments and their homologs in the 6th segment, the posterior telson flexor muscles. Nearly one-quarter of cord-transected animals responded to the stimuli with phasic flexor muscle activity by one week after the lesion, and almost 90% were responsive by 3 weeks.
3. Regeneration of axons across the lesion played little or no role in the recovery of phasic flexor muscle responsiveness. In addition, the lateral giant axons were not activated by the gradually applied stimuli that triggered phasic flexor muscle contractions. These results suggest that non-giant pathways confined to the abdominal nervous system become functional following chronic cord transection.
4. Retransection of the nerve cord below the original lesion showed that smaller subsets of the abdominal cord, including a single ganglion, could develop the ability to generate phasic flexor muscle contractions in response to gradually applied stimuli.
5. Phasic flexor motoneurons in cord-transected animals could be excited by stimulation of afferents throughout the abdomen. The sensory pathways producing this activation appear to project through the nerve cord without much cross-over between left and right sides.

     

Organization of the Nervous System and Sensory Organs in the Larva of the Marine Bryozoan Bowerbankia gracilis (Ctenostomata: Vesiculariidae): Functional Significance of the Apical Disc and Pyriform Organ

The organization of the nervous system and the histology and ultrastructure of the apical disc and the pyriform organ have been investigated by serial sections with light and electron microscopy for the larva of the vesiculariid ctenostome bryozoan Bowerbankia gracilis Leidy 1855. The nervous system consists of four major internal components: (1) a median-anterior nerve nodule; (2) an equatorial, subcoronal nerve ring; (3) paired aboral nerve cords; (4) paired antero-lateral nerve tracts. The nervous system is associated with the ciliated larval surface at the apical disc, the pyriform organ, the corona and the intercoronal cells. The paired aboral nerve cords extend from the apical disc to the nerve nodule, which gives rise to the paired antero-lateral nerve tracts to the pyriform organ and to paired lateral tracts that form the equatorial nerve ring. Ultrastructural evidence is provided for the designation of primary sensory cells in the neural plate of the apical disc and in the juxtapapillary regions of the pyriform organ. Efferent synapses are described between the equatorial nerve ring and the overlying coronal cells, which constitute the primary locomotory organ of the larva. The repertoire of potential functions of the apical disc and pyriform organ are discussed. It is concluded that the apical disc and pyriform organ constitute larval sensory organs involved in orientation and substrate selection, respectively. Their association with the major effector organs of the larva (the corona and the musculature) via the nervous system supports this interpretation.     

Integument and sensory nerve differentiation ofDrosophila leg and wing imaginal discs in vitro

Summary An ultrastructural analysis is presented of the cuticular and neural structures formed by the prothoracic leg and wing imaginal discs of maleDrosophila melanogaster larvae during culture in vitro with 0.2 g/ml of -ecdysone. A pupal cuticle, and subsequently an imaginal cuticle with a well-defined epicuticle and a laminated endocuticle is formed. The ultrastructure of the epidermis and of cuticular structures such as bristles, trichomes, apodemes, and tracheoles is very similar to that found in situ. Dendrites and nerve cell bodies are formed in vitro, and sensory axons form nerve bundles similar to those of normal appendages in situ, despite their isolation from the central nervous system. It is concluded that at the ultrastructural level, differentiation in vitro closely parallels the normal course of development.     

Intrastriatal injection of Parkinson’s disease intestine and vagus lysates initiates α-synucleinopathy in rat brain

Parkinson’s disease (PD) is characterized by the selective loss of dopaminergic neurons in the midbrain and the pathological accumulation of misfolded α-synuclein (α-syn) in the brain. A growing body of evidence suggests that the formation of misfolded α-syn and aggregation may begin in the peripheral nervous system, specifically the enteric nervous system, and then propagate to the central nervous system via the vagus nerve. However, the PD-like neuropathology induced by the intestine and vagus nerve extracts is rarely investigated. In this work, we injected lysates of the intestine and vagus obtained from a diagnosed PD patient, which contained abnormal α-syn aggregates, into the rat striatum unilaterally. Strikingly, such an injection induced dopaminergic neurodegeneration and α-syn depositions in the striatum, substantia nigra, and other brain regions, including the frontal cortex, somatosensory cortex, hypothalamus, brain stem, and cerebellum. Moreover, significant activation of microglia and the development of astrogliosis were observed in the substantia nigra pars compacta of the injected rats. These findings provide essential information for our understanding of PD pathogenesis, as we established for the first time that the α-syn aggregates in the intestine and vagus of a PD patient were sufficient to induce prion-like propagation of endogenous α-syn pathology in wild-type rats.Subject terms: Inflammation, Peripheral nervous system     

Embryonic and post-embryonic development of the polyclad flatworm Maritigrella crozieri; implications for the evolution of spiralian life history traits

Background

Planktonic life history stages of spiralians share some muscular, nervous and ciliary system characters in common. The distribution of these characters is patchy and can be interpreted either as the result of convergent evolution, or as the retention of primitive spiralian larval features. To understand the evolution of these characters adequate taxon sampling across the Spiralia is necessary. Polyclad flatworms are the only free-living Platyhelminthes that exhibit a continuum of developmental modes, with direct development at one extreme, and indirect development via a trochophore-like larval stage at the other. Here I present embryological and larval anatomical data from the indirect developing polyclad Maritrigrella crozieri, and consider these data within a comparative spiralian context.

Results

After 196 h hours of embryonic development, M. crozieri hatches as a swimming, planktotrophic larva. Larval myoanatomy consists of an orthogonal grid of circular and longitudinal body wall muscles plus parenchymal muscles. Diagonal body wall muscles develop over the planktonic period. Larval neuroanatomy consists of an apical plate, neuropile, paired nerve cords, a peri-oral nerve ring, a medial nerve, a ciliary band nerve net and putative ciliary photoreceptors. Apical neural elements develop first followed by posterior perikarya and later pharyngeal neural elements. The ciliated larva is encircled by a continuous, pre-oral band of longer cilia, which follows the distal margins of the lobes; it also possesses distinct apical and caudal cilia.

Conclusions

Within polyclads heterochronic shifts in the development of diagonal bodywall and pharyngeal muscles are correlated with life history strategies and feeding requirements. In contrast to many spiralians, M. crozieri hatch with well developed nervous and muscular systems. Comparisons of the ciliary bands and apical organs amongst spiralian planktonic life-stages reveal differences; M. crozieri lack a distinct ciliary band muscle and flask-shaped epidermal serotonergic cells of the apical organ. Based on current phylogenies, the distribution of ciliary bands and apical organs between polyclads and other spiralians is not congruent with a hypothesis of homology. However, some similarities exist, and this study sets an anatomical framework from which to investigate cellular and molecular mechanisms that will help to distinguish between parallelism, convergence and homology of these features.     

Acetylcholinesterase-containing nerve cells in the pineal complex and subcommissural area of the frogs,Rana ridibunda and Rana esculenta

Summary In Rana esculenta and Rana ridibunda the frontal organ and the pineal organ (epiphysis cerebri) form a pineal complex. Approximately 60 nerve cells of the frontal organ and 220–320 nerve cells of the pineal organ display a positive acetylcholinesterase reaction (Karnovsky and Roots, 1964). The dorsal wall of the pineal organ is considerably richer in acetylcholinesterase-positive neurons than the ventral wall (ratio 31); a group of unusually large-sized nerve cells occurs in the rostral portion of the frog pineal. Two different types of nerve cells were observed in the pineal complex: multipolar and pseudounipolar elements. The former are embedded in the pineal parenchyma and their processes penetrate radially into the plexiform layer, whereas the latter are distributed along the roots of the pineal tract near the basal lamina. The ratio of the multipolar to pseudounipolar neurons is 14 for the frontal organ and 35 for the pineal organ. The multipolar elements may be interneurons; the pseudouni-polar cells send one of their processes into the pineal tract. At the caudal end of the pineal organ 30–50 unipolar nerve cells are clustered in juxtaposition with the pineal tract, and other 30–50 unipolar neurons are scattered along the basis of the subcommissural organ. Some of these nerve cells emit their processes toward the mesencephalon and others toward the pineal organ via the pineal tract. The results are discussed with respect to previous physiological and morphological findings on the pineal complex of Anura.Supported by a fellowship from the Alexander von Humboldt Foundation, Federal Republic of Germany, to K. Wake. Completed November 22, 1973.Supported by the Deutsche Forschungsgemeinschaft.     

Neural activity of the frog's frontal organ during steady illumination

Summary The neural activity in the frontal organ nerve of frogs was recorded after 5 min of steady illumination. There was a monotonic decrease in the neural activity which could be defined by the equation, The exponenta varied from 0.15 to 0.23. This relationship held over a range of at least 6.0 log units, and the wavelength of the adapting light did not alter the results. It is suggested that these properties satisfy the requirements of a structure which could act as a dosimeter.We wish to thank Mr. O. Navarro for assistance with the experiment. Support for this work was provided by NEI- #EY00376-07.     

A self-organizing neural network sharing features of the mammalian visual system

This paper describes a neural network model whose structure is designed to closely fit neuroanatomical and-physiological data, and not to be most suitable for rigorous mathematical analysis.It is shown by computer simulation that a process of self-organization that departs from a fixed retinotopic order at peripheral layers and includes hebbian modifications of synaptic connectivity at higher processing levels leads to a system that is capable of mimicking various functions of visual systems:In the initial state the overall structure of the network is preset, individual connections at higher levels are randomly selected and their strength is initialized with random numbers.For this model the outcome of the self-organization process is determined by the stimulation during the developmental phase. Depending on the type of stimuli used the model can either develop towards a featureselective preprocessor stage in a complex vision system or towards a subsystem for associative recall of abstract patterns.This flexibility supports the hypothesis that the principles embodied are rather universal and can account for the development of various nervous system structures.Presented at teh 9th Cybernetics-Congress, Göttingen, March 1986     

A role for uninjured afferents in neuropathic pain

Diseases and injuries to the nervous system can lead to a devastating chronic pain condition called neuropathic pain. We review changes that occur in the peripheral nervous system that may play a role in this disease. Common animal models for neuropathic pain involve an injury to one or more peripheral nerves. Following such an injury, the nerve fibers that have been injured exhibit many abnormal properties including the development of spontaneous neural activity as well as a change in the expression of certain genes in their cell body. Recent data indicate that adjacent, uninjured nerve fibers also exhibit significant changes. These changes are thought to be driven by injury-induced alterations in the milieu surrounding the uninjured nerve and nerve terminals. Thus, alteration in neural signaling in both injured and uninjured neurons play a role in the development of neuropathic pain after peripheral nerve injury.