Transferrin is necessary and sufficient for the neural effect on growth in amphibian limb regeneration blastemas

Cell proliferation during the early phase of growth in regenerating amphibian limbs requires a permissive influence of nerves. Based on analyses of proliferative activity in denervated blastemas, it was proposed that nerves provide factors important for cells to complete the proliferative cycle rather than for mitogenesis itself. One such factor, the iron-transport protein transferrin (Tf), is abundant in regenerating peripheral nerves where it is axonally transported and released at growth cones. Using blastemas in organ culture, which have been widely used in previous investigations of the neural effect on growth, it was shown here that the growth-promoting activity of neural extract was completely removed by immuno-absorption with antiserum against Tf and restored by addition of Tf. Purified Tf or a low molecular weight ferric ionophore were as active as the neural extract in this assay, indicating that the trophic effect of Tf involves its capacity for iron delivery. Both Tf and ferric ionophore also maintained DNA synthesis in denervated blastemas in vivo . A dose-response assay indicated that purified axolotl Tf stimulates growth of cultured blastemal cells at concentrations as low as 100 ng/mL. The Tf mRNA in axolotl nervous tissue was shown by northern analysis to be similar in size to that of liver. These results are discussed together with those from previous in vitro studies of blastemal growth and support the hypothesis that cell division in the blastema depends on axonally released Tf during the early, nerve-dependent phase of limb regeneration.     

Impaired effect of relaxin on vasoconstrictor reactivity in spontaneous hypertensive rats

Relaxin is thought to be involved in vasodilation to pregnancy by increasing endothelium-dependent vasodilation and compliance, and decreasing myogenic reactivity. Primary (essential) hypertension predisposes to circulatory maladaptation and subsequent gestational hypertensive disease. This study aimed to determine that vascular responses to chronic exposure to relaxin are impaired in young female rats with primary hypertension. In 10–12 weeks old Wistar-Hannover rats (WHR) and spontaneous hypertensive rats (SHR), we determined vascular responses in isolated kidney and mesenteric arteries after 5-days of chronic exposure to relaxin (4 μg/h) or placebo. SHR show decreased sensitivity to phenylephrine (by 67%, p < 0.01) and renal perfusion flow (RPFF, by 19%, p < 0.01), but no changes in flow-mediated vasodilation, myogenic reactivity or vascular compliance. In WHR, relaxin stimulated flow-mediated vasodilation (2.67 fold, from 48 ± 9 to 18 ± 4 μl/min, p = 0.001), inhibited myogenic reactivity (from −1 ± 2 to 7 ± 3 μm/10 mm Hg, p = 0.01), and decreased sensitivity to phenylephrine (28%, from 1.39 ± 0.08 to 1.78 ± 0.10 μM, p < 0.01), but left compliance and RPFF unchanged. NO-blockade by l-NAME diminished most relaxin-mediated responses. In SHR, the vasodilator effects of relaxin were blunted for myogenic reactivity and sensitivity to phenylephrine, with similar effects on flow-mediated vasodilation, compliance, RPFF and equal Rxfp1 (relaxin family peptide receptor) gene expression, as compared to WHR. Primary hypertension blunts both the relaxin-induced inhibition of myogenic reactivity and α-adrenergic vasoconstrictor response, independent from Rxfp1 gene expression, while the relaxin-dependent enhanced flow-mediated vasodilation remains intact. This implies selective resistance to relaxin in young subjects suffering from primary hypertension.     

Licht- und fluoreszenzmikroskopische Untersuchungen zur Innervation des Luftsacksystems der Vögel

Zusammenfassung Die Innervation der Wandungen des abdominalen Luftsacks und der thorakalen Luftsäcke sowie des horizontalen und schrägen Septum wird bei Haushuhn (Gallus domesticus L.) und Höckerschwan [Cygnus olor (Gmelin)] untersucht mit zwei Versilberungstechniken und der Falck-Hillarp-Methode zur Demonstration biogener Amine. In allen Luftsäcken finden sich adrenerge Plexus, die teilweise zum Gefäßsystem und zur glatten Muskulatur der Luftsackwandung in Beziehung stehen, und ausgedehnte ganglienzellhaltige (parasympathische) Nervennetze. Große Teile der Plexus können keiner identifizierbaren Struktur zugeordnet werden. Die quantitative Bestimmung des Katecholamingehaltes in glattmuskulärem Gewebe von Huhn und Schwan (M. tensor septi obliqui) zeigt erhebliche Differenzen. Beim Huhn ist nur Noradrenalin nachweisbar; beim Schwan finden sich hingegen eine wesentlich höhere Noradrenalinkonzentration, große Mengen an Adrenalin und Spuren von Dopamin. Bei beiden Arten sind in den thorakalen Luftsäcken sensible Endigungen vorhanden, die besonders beim Schwan eine große Mannigfaltigkeit zeigen. Die funktionelle Bedeutung der Befunde, insbesondere die Relevanz der Rezeptoren des Luftsacksystems für die nervöse Steuerung der Atmung, wird unter Berücksichtigung experimentell-physiologischer Untersuchungen diskutiert. Es zeigt sich dabei, daß eine eindeutige Korrelation der morphologischen und der physiologischen Befunde zur Zeit nicht möglich ist.

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The innervation of the avian air-sac system an investigation by means of the light and fluorescence microscope

Summary The innervation of the walls of the abdominal and the thoracic air sacs and of the horizontal and oblique septa of the domestic fowl and the mute swan have been investigated by means of two silver-impregnation techniques and by the method of Falck-Hillarp for demonstration of biogenic amines. In the air sacs there are adrenergic plexus associated with the vascular system, and with the smooth musculature of the septa and air sac walls; there is also a widespread (parasympathetic) nerve net containing ganglion cells. Large parts of the plexus cannot be associated with any identifiable structure. The quantitative detection of the catecholamines in the smooth-muscle tissue of the oblique septum of the two species reveals considerable differences. In the domestic fowl only noradrenaline is present. In the swan, on the contrary, the noradrenaline level is much higher; there is also a large amount of adrenaline, and a trace of dopamine is detectable. The walls of the thoracic air sacs of both species contain sensory endings; in the swan these are of diverse types. The functional importance of the results, and, in particular, the relation of the receptors of the air-sac system to the nervous control of ventilation, have been discussed in regard to experimental physiological investigations. It is not yet possible to present an unequivocal correlation between the results of morphological and physiological investigations.

Medizinische Dissertation unter Anleitung von Priv.-Doz. Dr. Dr. H.-R. Duncker.     

Ultrastructure of microtubules in dermal melanophores and spinal nerve of the Antarctic teleost Pagothenia borchgrevinki

Summary The antarctic teleost, Pagothenia borchgrevinki inhabits the Antarctic Ocean where the water temperature remains around -1.9° C throughout the year. Dermal melanophores of this fish respond within minutes to epinephrine and theophylline with melanosome aggregation and dispersion, respectively. Numerous cytoplasmic microtubules are present in these cells despite the low environmental temperature. In longitudinal profiles, many microtubules are twisted, beaded and sometimes even branched. In cross sections, C-, U-, S-, 6- and other irregularly shaped tubules are observed. Nocodazole partially disrupts microtubules and inhibits epinephrine-induced pigment aggregation. Pigment movements are also prevented by erythro-9-[3-(2-hydroxynonyl)] adenine. Although the participation of these incomplete microtubules in cell motility remains uncertain, the results indicate that this fish has a cold-resistant microtubule system on which melanosome movements depend. Unlike those in melanophores, microtubules in the axons of spinal nerves are of uniform thickness and often contain an electron-dense core in the center.     

Further evidence for the existence of intralobular nerves in the rat liver

Summary In a recent study (Skaaring and Bierring, 1976) we found cholinesterase positive nerve-like structures in the lobules of rat liver, and scanning electron microscopy revealed cords having a distribution pattern similar to that of the cholinesterase-positive structures. To obtain further evidence for an intralobular nerve supply the methods of cobalt and Procion Yellow nerve staining (Stretton and Kravitz, 1968; Iles and Mulloney, 1971; Pitman, Tweedle and Cohen, 1972) were adapted, iontophoretic introduction of the dyes being attempted through cut axonal ends in the surface of small excised blocks of rat liver.     

Intragastric administration of AMG517, a TRPV1 antagonist,enhanced activity-dependent energy metabolism via capsaicin-sensitive sensory nerves in mice

ABSTRACT

Transient receptor potential vanilloid 1 (TRPV1), a nociceptive cation channel, is known to play roles in regulating the energy metabolism (EM) of the whole body. We previously reported that TRPV1 antagonists such as AMG517 enhanced EM in mice, however, these mechanisms remain unclear. The aim of this study was to explore the mechanisms underlying the enhancement of EM by AMG517, a selective TRPV1 antagonist, in mice. Respiratory gas analysis indicated that intragastric administration of AMG517 enhanced EM along with increasing locomotor activity in mice. Next, to clarify the possible involvement with afferent sensory nerves, including the vagus, we desensitized the capsaicin-sensitive sensory nerves of mice by systemic capsaicin treatment. In the desensitized mice, intragastric administration of AMG517 did not change EM and locomotor activity. Therefore, this study indicated that intragastric administration of AMG517 enhanced EM and increased locomotor activity via capsaicin-sensitive sensory nerves, including vagal afferents in mice.     

Effects of heterologous cross-suture between the postganglionic sympathetic and the preganglionic parasympathetic nerve trunks of submandibular glands in cats

Summary After sectioning the postganglionic adrenergic sympathetic nerve trunk for the submandibular gland, as close to the submandibular artery as practicable, its central end was sutured to the peripheral end of the preganglionic cholinergic parasympathetic nerve trunk for the gland, the chorda, which had been sectioned where it left the lingual nerve. The effects of this heterologous cross-sature were studied at different times, up to 1 year afterwards, by assessing the physiological and pharmacological responses of the glands and the neuro-histochemical changes in the nerve trunks and in the nerves within the glands.In all cases adrenergic sympathetic nerves grew across the site of suture and down the erstwhile cholinergic parasympathetic trunk, eventually to develop connections in the gland. In some cases the functional adrenergic reinnervation of the submandibular gland appeared to result exclusively or predominantly from the direct downgrowth of adrenergic axons to the gland, via the crossed nerves. In other cases however, in addition to a direct glandular reinnervation, there was some physiological and morphological evidence which suggested that possible heterogenous synaptic contacts may have been created between postganglionic sympathetic axons and cholinergic ganglion cells in the chorda nerve.This work was supported by a grant from the Joint Research Committee, King's College Hospital.     

Subsurface near‐infrared laser stimulation of the periprostatic cavernous nerves

Successful identification and preservation of the cavernous nerves (CN), which are responsible for sexual function and vulnerable to damage during prostate cancer surgery, will require subsurface detection of the CN's beneath a thin fascia layer. This study explores the feasibility of optical nerve stimulation (ONS) in the rat with a fascia layer placed over the CN. Two near‐infrared diode lasers with wavelengths of 1455 and 1550 nm were operated in continuous‐wave mode for stimulation of the CN in 8 rats, in vivo. Successful ONS was confirmed by an intracavernous pressure (ICP) response in the rat penis at 1455 nm through fascia with a thickness up to 110 μm and at 1550 nm through fascia with a thickness up to 450 μm. Higher incident laser power was required to produce an ICP response as fascia thickness was increased. Also, weaker and slower ICP responses were observed as fascia thickness was increased. Subsurface ONS of the rat CN at a depth of 450 μm using a 1550 nm laser is feasible as an intermediate step towards developing ONS as an intra‐operative diagnostic tool for identification and preservation of the cavernous nerves during prostate cancer surgery. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Differential inhibition of noradrenaline release mediated by inhibitory A1-adenosine receptors in the mesenteric vein and artery from normotensive and hypertensive rats

Mesenteric arteries and veins are densely innervated by sympathetic nerves and are crucial in the regulation of peripheral resistance and capacitance, respectively, thus, in the control of blood pressure. Presynaptic adenosine receptors are involved in vascular tonus regulation, by modulating noradrenaline release from vascular postganglionic sympathetic nerve endings. Some studies also suggest that adenosine receptors (AR) may have a role in hypertension. We aim at investigating the role of presynaptic adenosine receptors in mesenteric vessels and establish a relationship between their effects (in mesenteric vessels) and hypertension, using the spontaneously hypertensive rats (SHR) as a model of hypertension. Adenosine receptor-mediated modulation of noradrenaline release was investigated through the effects of selective agonists and antagonists on electrically-evoked [³H]-noradrenaline overflow. CPA (A₁AR selective agonist: 1–100 nM) inhibited tritium overflow, but the inhibition was lower in SHR mesenteric vessels. IB-MECA (A₃AR selective agonist: 1–100 nM) also inhibited tritium overflow but only in WKY mesenteric veins. CGS 21680 (A_2AAR selective agonist: up to 100 nM) failed to facilitate noradrenaline release in mesenteric veins, from both strains, but induced a similar facilitation in the mesenteric arteries. NECA (non-selective AR agonist: 1, 3 and 10 μM), in the presence of A₁ (DPCPX, 20 nM) and A₃ (MRS 1523, 1 μM) AR selective antagonists, failed to change tritium overflow. In summary, the modulatory effects mediated by presynaptic adenosine receptors were characterized, for the first time, in mesenteric vessels: a major inhibition exerted by the A₁ subtype in both vessels; a slight inhibition mediated by A₃ receptors in mesenteric vein; a facilitation mediated by A_2A receptors only in mesenteric artery (from both strains). The less efficient prejunctional adenosine receptor mediated inhibitory effects can contribute to an increase of noradrenaline in the synaptic cleft (both in arteries and veins), which might conduce to increased vascular reactivity.     

Anatomical studies on Margaritifera margaritifera and Cumberlandia monodonta (Mollusca: Pelecypoda: Margaritiferidae)

The family Margaritiferidae has received little serious anatomical study since the early twentieth centurv. The present paper attempts to provide information, derived from relaxed preserved and living material, on aspects of the mantle anatomy and neuroanatomy of two species, Margaritifera margaritifera and Cumberlandia monodonta . An historical overview of the systematics of the family is provided along with a proposed division of major groups within the genus Margaritifera .
The diaphragm of margaritiferids is complete, rather than incomplete as previously interpreted, and is formed bv both the gills and the diaphragmatic septa, the latter of which, in life, cover a portion of the posterior outer gill demibranchs and separate the branchial and suprabranchial chambers. Union of the diaphragmatic septa posteriorly draws the mantle margins together, separating the inhalent and exhalent apertures and thus completing the diaphragm.
The general visceral nervous system of each species is consistent with that of other bivalves. Differences from other unionaceans include the possession of a small, as opposed to a large, dorsal supra-anal bifurcation. Also, each of the two species studied lacks the anterior loop of the branchial nerve reported in some other unionaceans.