Primary afferent depolarization distribution of the γ-aminobutyric acid system in frog spinal cord

In the frog spinal cord primary afferent depolarization (PAD) constitutes a powerful inhibitory control mechanism. It has been suggested that -aminobutyric acid (GABA) is the transmitter substance involved in the genesis of PAD. In these studies we show that maximal glutamic acid decarboxylase activity is localized roughly 400–600 m from the dorsal surface, and that correlates well with the intraspinal distribution of field potentials associated with PAD. Measurement of GABA in serial spinal cord sections cut in a dorsal-ventral direction shows that high levels of GABA are seen at 400–600 m, with a peak at 800 m from the dorsal surface. Stimulation at frequencies shown to produce PAD augments the release of endogenous GABA from a superfused frog hemicord preparation.     

Histochemical study of the pre—and postnatal development of acetylcholinesterase in the rat spinal cord

The distribution of acetylcholinesterase(AChE)-positive structures in the developing rat spinal cord was studied with AChE-histochemistry.AChE-positive perikarya were first seen on embryonic day 14(E14) in the ventrolateral portion of the spinal cord.From that time onward.AChE=containing cells appeared gradually in the intermediate gray,dorsal horn and lateral spinal nucleus of the spinal cord in a ventral-to-dorsal,and lateral-to-medial order.No obvious rostral-to-caudal sequence was found.At birth,the distribution pattern of AChE-positive perikarya was basically similar to that in adults.After birth a dramatic increase in the AChE staining intensity extended from postnatal day 5(P5) to postnatal day 21(P21),In addition,two phases of transient AChE staining were observed in the external surface of the dorsal horn from embryonic day 15(E15) to embryonic day 21(E21) and in the marginal layer from embryonic day 21(E21) to postnatal day 14(P14),respectively.     

Regional distribution of α-neo-endorphin in rat brain and pituitary

α-Neo-endorphin was isolated as the first form of “big” Leu-enkephalin and its complete amino acid sequence has recently been established. Using an antiserum raised against synthetic α-neo-endorphin, a highly sentitive and specific radioimmunoassay was developed. The antiserum practically possesses no cross-reactivity to Leu-enkephalin, dynorphin[1–13] and PH-8P, and very little to β-neo-endorphin. Distribution of α-neo-endorphin has been determined in rat brain and pituitary by the use of the highly specific antiserum. The highest concentration was observed at posterior lobe of pituitary. Furthermore, immunoreactive α-neo-endorphin was characterized by gel-filtration and high performance liquid chromatography, and shown to be identical with authentic α-neo-endorphin.     

Δ-9-Tetrahydrocannabinol increases prodynorphin and proenkephalin gene expression in the spinal cord of the rat

Hypoalgesia induced by cannabinoid drugs has been found to implicate the opioid system. The effect of five days treatment with Δ-9-tetrahydrocannabinol (THC) was examined on prodynorphin (PDYN) and proenkephalin (PENK) gene expression in the spinal cord of male rats. PDYN and PENK gene expression was estimated measuring by northern blot analysis mRNA levels in the whole spinal cord, containing perikarya of these neurons. The subchronic treatment with THC (5 mg/kg/day; 5 days; i.p.) produced an increase in PDYN (39%) and PENK (34%) gene expression when compared with the vehicle treated group. These results suggest that the effects of THC in the spinal cord involve an increase in opioid activity, and therefore sustain the hypothesis of an interaction between the cannabinoid and opioid systems in this region.     

Comparative scanning and transmission electron microscopy studies of the ependyma of the central canal in the spinal cord of primates. I. Electron optical image of the ependyma in the central canal of the spinal cord of the callithrix monkey (Callithrix jacchus, Linné 1758)

The ependyma lining the central canal of the spinal cord of adult males and females monkey, Callithrix jacchus, was examined by scanning and transmission electron microscopy. The cross section of the lumen of the central canal are round, oval, or triangular. Light and dark ependymal cells, depending on the density of the cytoplasm, were found. The light ependymal cells are fewer than the dark cells. The ependyma cytoplasm contained numerous mitochondria, filamentous structures, one or more well-developed Golgi-complexes, vesicles of the smooth endoplasmic reticulum, ribosomes, lysosomes, multivesicular bodies, profiles of the rough endoplasmic reticulum, large osmophilic bodies, and microtubules. The nuclei of the ependyma cells usually have a simple, regular round or oval shape. They occupy a relatively large portion of the cell volume and lie in the central or mediobasal position. Some of the nuclei show deep invaginations into the karyoplasm. Most of the mitochondria occupy mainly the supranuclear portion of the apical cytoplasm. There are of the crista-typ. Ribosomes occur free in the cytoplasm, but some attached to the profiles of the rough endoplasmic reticulum or being arranged as polysomes. The filamentous structures are generally prominent cytoplasmic components and are distributed at the apical, lateral, or basal region of the ependymocytes. They are grouped into bundles and arranged in parallel arrays. Some of these bundles reach the plasmamembrane at the free lumina of the central canal, others take contact to the filamentous structures of the zonulae adherentes of the junctional complex below the free surface. The granular endoplasmic reticulum shows specializations. There profiles surrounding granular substances and widely distributed granulations in connection with the nuclear envelope. The functional significance of the deposition of these granulations is still unknown. The luminal surface of the ependymocytes bears many microvilli and cilia. The cilia are regularly arranged in cranio-caudal direction. Each cilium has the typical (9 + 2)-subfibres. The intercellular space at the surface of the ependymal layer shows a single zonula adherens or zonulae adherentes in the row. Tight junctions and gap junctions were not found in the material examined. Cell processes of liquor contacting neurons between adjacent ependyma cells, protruding into the lumen of the central canal, could be observed. The termination of these neurons contains accumulations of mitochondria in the central part, large amounts of vesicles, and small dense bodies. They have short microvilli and some stereocilia at the free surface.(ABSTRACT TRUNCATED AT 400 WORDS)     

Histochemical studies on the distribution of β-glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of the rat

Summary The present study compares the distribution of -glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of rat. In young cells there are indications of cyclic activity of these enzymes, i.e., in some stages there are perinuclear concentrations of the enzymes, at other times -glucuronidase and succinic dehydrogenase are uniformly distributed throughout the cytoplasm. These stages have been discussed with the identical distribution of mitochondria. However, in old spinal ganglion cells both -glucuronidase and succinic dehydrogenase become mainly concentrated in the pigment areas, suggesting thereby their possible role in the production of pigment, through the medium of the mitochondria.     

Colocalization of protein kinase C ⊺-subtype and calcitonin gene-related peptide in rat spinal cord

Summary Colocalization of calcitonin gene-related peptide (CGRP) and protein kinase C -subtype (PKC-) like immunoreactivities (LI) and the subcellular localization of CGRP-LI were studied in the ventral horn of rat spinal cord. Ultrastructurally CGRP-LI was localized on the membranes of the Golgi-complexes, in multivesicular bodies and in vesicles adjacent to the Golgi-complex in motoneuron perikarya. The colocalization of PKC- and CGRP-LI was detected in most of the ventral horn motoneurons. However, few motoneurons were only PKC--immunoreactive. These results suggest that PKC- may be involved in the regulation of CGRP release from motoric axon terminals.     

Responses of the spinal α-motoneurone-Renshaw cell system to various differentially distributed segmental afferent and descending inputs

A previously presented multi-loop model of the mammalian spinal -motoneurone-Renshaw cell system was extended to incorporate different physiological input patterns: Ia fibres from primary muscle spindle endings, spinal input systems descending in the ventral quadrant and from the nucleus ruber. The main goal of the computer simulation calculations was to present a number of dynamic input-output relations between these inputs which are distributed inhomogenously to different types of -MNs (that is, S-, FR-, and FF-type MNs) and the outputs of pools of the latter, for the purpose of experimental testing. The main outcome was that the phase relations of the outputs of the different types of MNs depend very much on the overall strength of recurrent inhibition, such that small changes of this strength, which appears to be small anyway, can significantly alter these phase relations. Since this strength is alterable through descending and segmental afferent inputs, this provides a physiological means of phase-decorrelation although it is unlikely to put the discharges of different MN types totally out of phase (by about 180°). Also, the inhomogeneity of recurrent inhibition would help to prevent a strong phase separation of this kind. Yet a decorrelation at the microscopic level could help suppress physiological tremor.     

Cystathionine β-synthase in structural elements of the human brain and spinal cord

By means of the immunohistochemical method, the presence and distribution of cystathionine β-synthase (CBS) was studied in nerve cells of the spinal cord and brainstem nuclei in eight men aged 18–44 years who had died as a result of causes not connected with damage to the central nervous system. CBS-positive neurons are revealed in all studied brain parts, in which their content varied in different nuclei from 0.9 to 17%. Large cells of motor nuclei more often had high and very high density of the reaction product deposition. In sensory nuclei the high portion was of small neurons with low intensity of the enzymatic reaction.     

Morphology and distribution of Müller cells in the retina of the toad Bufo marinus

We have previously shown that an antibody against neuron-specific enolase (NSE) selectively labels Müller cells (MCs) in the anuran retina (Wilhelm et al. 1992). In the present study the light- and electron-microscopic morphology of MCs and their distribution were described in the retina of the toad, Bufo marinus, using the above antibody. The somata of MCs were located in the proximal part of the inner nuclear layer and were interconnected with each other by their processes. The MCs were uniformly distributed across the retina with an average density of 1500 cells/mm². Processes of MCs encircled the somata of photoreceptor cells isolating them from each other by glial sheath, except for those of the double cones. Some of the photoreceptor pedicles remained free of glial sheath. Electron-microscopic observations confirmed that MC processes provide an extensive scaffolding across the neural retina. At the outer border of the ganglion cell layer these processes formed a non-continuous sheath. The MC processes traversed through the ganglion cell layer and spread beneath it between the neuronal somata and the underlying optic axons. These processes formed a continuous inner limiting membrane separating the optic fibre layer from the vitreous tissue. Neither astrocytic nor oligodendrocytic elements were found in the optic fibre layer. The significance of the uniform MC distribution and the functional implications of the observed pattern of MC scaffolding are discussed.     

Involvement of binding lipoproteins in the absorption and transport of α-tocopherol in the rat

1. Specific lipoproteins binding alpha-tocopherol but not its known metabolites have been isolated and identified from cytosol of rat intestinal mucosa and from serum. 2. A timestudy of the appearance of the orally administered alpha-[(3)H]tocopherol with these lipoproteins indicates that very-low-density lipoprotein of serum acts as a carrier of the vitamin. 3. The involvement of the mucosal lipoprotein in the absorption of the vitamin from the intestine has been inferred from observations on the amounts of alpha-tocopherol in serum of orotic acid-fed rats where release of lipoproteins from the liver to serum is completely inhibited. A considerable decrease in the association of alpha-tocopherol with serum very-low-density lipoprotein under this condition is interpreted to mean that serum lipoproteins are limiting factors for the transport of the vitamin across the intestine and that this is possibly effected by exchange of alpha-tocopherol between serum very-low-density lipoprotein and mucosal lipoprotein.     

Distinct systemic distribution of salusin-α and salusin-β in the rat

Salusin-α and salusin-β are multifunctional bioactive peptides that were initially predicted using in silico analyses. These peptides should be concomitantly biosynthesized from prosalusin in humans. However, little information is available yet on the biosynthesis and mode of presence of salusin-α and salusin-β in non-human species. In the present study, we examined whether salusin-α and salusin-β are conserved in the rat and whether salusin-α and salusin-β show distinct systemic distributions. Immunohistochemical analysis of rat tissues using a specific anti-rat salusin-α antibody detected immunoreactivity extensively in neuronal cells and fibers, and abundantly in the epithelial tissues throughout the organs. This distribution contrasts sharply with that of salusin-β, which is mainly localized to the neuroendocrine and hematopoietic systems. Western blot analysis of rat spleen extracts showed the presence of cleaved fragments corresponding to putative rat salusin-α. Reverse-phase and gel filtration high performance liquid chromatography analyses coupled with radioimmunoassay detection of rat urine extracts revealed a major immunoreactive component that co-eluted with synthetic putative rat salusin-β. These data support the processing of rat prosalusin into salusin-α and salusin-β despite absent dibasic amino acids between the two.     

Resolution of sensory and mucoid glycoconjugates with terminal α-galactose residues in the mucomicrovillar complex of the vomeronasal sensory epithelium by dual confocal laser scanning microscopy

The organization of the mucomicrovillar complex of the vomeronasal sensory epithelium of adult rats was examined using confocal laser scanning microscopy. In specimens labeled with the FITC-conjugated isolectin B₄ of Bandeiraea simplicifolia, which recognizes terminal -galactose sugar residues of glycoconjugates, we demonstrated that the mucomicrovillar complex was composed of islet-like structures with a high-density -galactose core. The mucomicrovillar complex was further resolved into sensory and mucoid components in double-labeling and dual scanning experiments. The sensory component, which consists of the dendritic terminals of olfactory marker protein-immunoreactive vomeronasal receptor neurons, contained cytosolic glycoconjugates with terminal -galactose sugar residues. The extracellular mucoid component consisted of glycoconjugates containing terminal -galactose derived from the glands associated with the vomeronasal organ. These results demonstrated the complex microchemical organization of the sensory and mucoid components of the mucomicrovillar complex.     

Absorption of α-MSH from subcutaneous and intraperitoneal sites in the rat

Pentobarbitone anesthetized rats were injected with 30 nmol (50 μg) α-MSH administered intraperitoneally (IP) and subcutaneously (SC) in an acid-saline vehicle, or SC in a zinc phosphate vehicle. Concentrations of α-MSH in plasma were measured by radioimmunoassay. The pharmacokinetic parameters for the three modes of administration were determined by fitting a one-compartment open model to the plasma level data. The $\text{t}\text{1}\text{2}$ for absorption using the saline vehicle was 7.3 and 5.6 min from the IP and SC sites, respectively. The $\text{t}\text{1}\text{2}$ for absorption from the zinc phosphate complex of 17.7 min was significantly longer. Five percent of the IP dose was absorbed into the systemic circulation giving a peak plasma level of 14.1 nmol/l. The absorption of 2–3 percent was significantly lower following SC administration; peak plasma levels were 8.3 and 4.8 nmol/l for the saline and zinc phosphate vehicles, respectively. The low percentage absorption values indicated a high degree of metabolism of the peptide by peripheral tissues on its passage from the injection sites into the circulation.     

The three-dimensional distribution of αA-crystalline in rat lenses and its possible relation to transparency

Lens transparency depends on the accumulation of massive quantities (600-800 mg/ml) of twelve primary crystallines and two truncated crystallines in highly elongated "fiber" cells. Despite numerous studies, major unanswered questions are how this heterogeneous group of proteins becomes organized to bestow the lens with its unique optical properties and how it changes during cataract formation. Using novel methods based on conical tomography and labeling with antibody/gold conjugates, we have profiled the 3D-distribution of the αA-crystalline in rat lenses at ～2 nm resolutions and three-dimensions. Analysis of tomograms calculated from lenses labeled with anti-αA-crystalline and gold particles (～3 nm and ～7 nm diameter) revealed geometric patterns shaped as lines, isosceles triangles and polyhedrons. A Gaussian distribution centered at ～7.5 nm fitted the distances between the ～3 nm diameter gold conjugates. A Gaussian distribution centered at ～14 nm fitted the Euclidian distances between the smaller and the larger gold particles and another Gaussian at 21-24 nm the distances between the larger particles. Independent of their diameters, tethers of 14-17 nm in length connected files of gold particles to thin filaments or clusters to ～15 nm diameter "beads." We used the information gathered from tomograms of labeled lenses to determine the distribution of the αA-crystalline in unlabeled lenses. We found that αA-crystalline monomers spaced ～7 nm or αA-crystalline dimers spaced ～15 nm center-to-center apart decorated thin filaments of the lens cytoskeleton. It thus seems likely that lost or gain of long-range order determines the 3D-structure of the fiber cell and possible also cataract formation.