Dorsal Bodies Research Articles

The distribution and origin of VIP in the spinal cord of six mammalian species

The distribution of VIP-immunoreactivity was studied in the spinal cord and dorsal root ganglia of 6 mammalian species. Immunoreactive fibres and cell bodies were most apparent in the dorsal horn, dorsolateral funiculus, intermediolateral cell columns and the area around the central canal. The distribution of VIP immunoreactivity was similar in all species studied, mouse, rat, guinea pig, cat, horse and the marmoset monkey. There were fewer VIP fibres in the dorsal horn of cervical and thoracic segments than in lumbosacral segments. Using radioimmunoassay this gradient increase was quantitatively most marked in the sacral spinal cord of the cat. In dorsal root ganglia few nerve cell bodies but numerous fibres were present. A dual origin for VIP in the spinal cord is suggested: (A) Extrinsic, from dorsal root afferent fibres since immunoreactivity was decreased in dorsally rhizotomized animals (cats and rats) and in capsaicin pretreated rats (microinjection of dorsal root ganglia). (B) From local cell bodies intrinsic to the spinal cord which became visible after colchicine pretreatment of rats.

Effects of elevated haemolymph levels of the female gonadotropic dorsal body hormone on the cercarial production ofTrichobilharzia ocellata inLymnaea stagnalis

Juvenile specimens ofLymnaea stagnalis were exposed to 0 or 4 miracidia ofTrichobilharzia ocellata. The effects of experimentally raised haemolymph levels of the female gonadotropic dorsal body hormone (DBH) on female reproduction of the host were studied, and the effect on the production of cercariae was determined. Operations of snails and implantations of endocrine dorsal bodies (DB) were performed shortly after infection in three successive experiments. DB implants in non-infected snails (+DB snails) advanced the onset of ovipository activity and enhanced oocyte production compared to that in appropriate controls. In this the increase in haemolymph level is proved of DBH produced by the DB grafts. Infected +DB snails did not show any increase in the various aspects of female reproductive activity. DB implants also did not affect the production of cercariae. Thus the blocking action by the parasites on the development of the reproductive system could not be counteracted by elevating the DBH level in the haemolymph. These results are consistent with the hypothesis that the parasites intervene in the reproductive activity of the host at the level of the targets of the gonadotropic hormones.

Increased activity of the female gonadotropic hormone producing dorsal bodies in Lymnaea stagnalis infected with Trichobilharzia ocellata.

Juvenile specimens of Lymnaea stagnalis were exposed to 0 or 4 miracidia of Trichobilharzia ocellata. Dissection followed at day 22 post exposure. The effects of infection on the activity of the female gonadotropic hormone producing Dorsal Bodies (DB) were studied by phase-contrast and electron microscopy. Morphometry shows that the relative volume of DB cells of infected snails is 1.6 times as high as in controls. This is mainly due to a 45% higher cytoplasmic volume. The number of profiles of the Golgi apparatus increases by nearly 90% and the Golgi volume by 40% as a result of infection. Numerous omega-shaped indentations of the plasma membrane of the DB cell processes indicate the release of the contents of the DB hormone containing elementary granules. It is concluded that parasitic infection causes a clear increase in the synthetic activity of the DB. Most probably, the parasites exert the inhibiting effects on reproductive activity at the level of the targets of the reproductive hormones.

Changes in Catecholaminergic Neurons in Medulla Oblongata of Spontaneously Hypertensive rat

We determined catecholamine (CA) content in brain of spontaneously hypertensive rat (SHR) and observed a decrease of noradrenarine (NA) content in the brain stem as previous report. Then we used Glutaraldehyde-formaldehyde fluorescence method for histochemical study. Fluorescence of ventral Al and dorsal A2 cell bodies in medulla oblongata was decreased. NA accumulation in caudal nervous ending of nucleus tractus solitarius (NTS) was reduced in SHR of pre-hypertensive stage aged 4 weeks. There were no changes in other regions, thalamus, hypothalamus, substantia nigra, locus ceruleus and periventricular nucleus.

The distribution and origin of VIP in the spinal cord of six mammalian species

The distribution of VIP-immunoreactivity was studied in the spinal cord and dorsal root ganglia of 6 mammalian species. Immunoreactive fibres and cell bodies were most apparent in the dorsal horn, dorsolateral funiculus, intermediolateral cell columns and the area around the central canal. The distribution of VIP immunoreactivity was similar in all species studied, mouse, rat, guinea pig, cat, horse and the marmoset monkey. There were fewer VIP fibres in the dorsal horn of cervical and thoracic segments than in lumbosacral segments. Using radioimmunoassay this gradient increase was quantitatively most marked in the sacral spinal cord of the cat. In dorsal root ganglia few nerve cell bodies but numerous fibres were present. A dual origin for VIP in the spinal cord is suggested: (A) Extrinsic, from dorsal root afferent fibres since immunoreactivity was decreased in dorsally rhizotomized animals (cats and rats) and in capsaicin pretreated rats (microinjection of dorsal root ganglia). (B) From local cell bodies intrinsic to the spinal cord which became visible after colchicine pretreatment of rats.

Synchronous maturation of the female reproductive system and of the ovulation hormone-producing system in Lymnaea stagnalis

The intercerebral commissures (COMs) of young snails, which are in the male stage (10–15 mm shell height), contain only small quantities of ovulation hormone (CDCH): 0.6 OIU · COM −1 · g −1 snail (1 ovulation inducing unit = threshold dose for ovulation in adult recipients). During the subsequent period of female maturation the quantities of CDCH increase considerably up to a maximum of 47 OIU · COM −1 · g −1 snail at the onset of oviposition. In snails smaller than ca. 21 mm shell height oviposition cannot be induced by COM extract injections. It is concluded that maturation of the female reproductive system and of the ovulation hormone system occur simultaneously, and that both processes are stimulated by the hormone of the dorsal bodies (endocrine organs located upon the cerebral ganglia).

Does pyruvate prevent acrylamide neurotoxicity?: Implications for disease pathogenesis

We used the prototype environmental neurotoxin, acrylamide monomer, to evaluate the hypothesis that neurotoxin-induced nerve fiber degeneration results from inactivation of axonal glycolytic enzymes. Treating intoxicated rats with sodium pyruvate, we hypothesized, would bypass the putative neurotoxin-induced blockade in glycolysis, thus ameliorating neurobehavioral and morphologic measures of neurotoxicity. After establishing that pyruvate itself did not affect behavior, we examined its effects on acrylamide-intoxicated animals. Pyruvate treatment had a significant effect on only one of eight neurobehavioral measures, though others showed similar trends. A morphologic observation of lumbar dorsal root ganglion cell bodies and peripheral nerves failed to show an effect of pyruvate. Those results suggested that inactivation of glycolytic enzymes alone is not a sufficient explanation of pathogenesis.

Effects of two gonadotropic hormones on polysaccharide synthesis in the albumen gland of Lymnaea stagnalis, studied with the organ culture technique

A medium for culturing organs of the basommatophoran freshwater snail Lymnaea stagnalis is described. One of the accessory sex glands, the albumen gland, which produces proteins and galactogen as nutritive substances for the embryos, was cultured along with parts of the central nervous system (CNS), including the female gonadotropic hormone-producing dorsal bodies (DB). Culture time was 4 days. The cerebral ganglia and the DB appeared to have a strong stimulating influence on polysaccharide synthesis in the albumen gland. The remaining part of the CNS has a weak stimulating effect. The use of extracts (culture time 6–26 hr) of parts of the cerebral ganglia and of the DB showed that not only the dorsal body hormone (DBH), but also the ovulation hormone (CDCH)—a neurohormone produced by the caudodorsal cells located in the cerebral ganglia—stimulates the synthetic activity of the albumen gland. The action of these hormones is direct; i.e., it is not exerted via the gonad. Dose- and time-response relations for the DBH and the CDCH are very similar. No additional rise in stimulation occurred when the two hormones were administered together. Experiments with albumen glands of adult snails demonstrated that the presence of large quantities of secretory material in the gland inhibits the response to DBH and CDCH.

α-Bungarotoxin binding sites on sensory neurones and their axonal transport in sensory afferents

The autoradiographic localization of [ 125I]α-bungarotoxin binding sites on primary sensory fibres was investigated. Nicotinic α-bungarotoxin binding sites were localized to a small sub-population of large dorsal root ganglion cells in the rat, monkey, cat and human dorsal root ganglia. Ligation of the sciatic nerve or dorsal root in the rat resulted in an anterograde accumulation of binding sites proximal to the dorsal root ganglion, and a small retrograde accumulation. Unilateral dorsal root section in the rat produced a loss of toxin binding sites mainly within lamina III of the dorsal horn. These results suggest that nicotinic α-bungarotoxin binding sites manufactured in large dorsal root ganglion cell bodies are transported both centrally to the spinal cord and also peripherally.

Effect of the photoperiod on the time schedule of egg mass production in Lymnaea stagnalis, as induced by ovulation hormone injections

In the pulmonate snail Lymnaea stagnalis the neurosecretory caudo-dorsal cells (CDC) produce an ovulation hormone (CDCH) which is released at the periphery of the cerebral commissure (COM). Time schedules of the successive stages of the egg mass production following CDCH injection (COM extract) were determined at 20°. Ovulation is performed rapidly, within 10 to 20 min. The latencies of the other stages are: egg formation, 20–30 min; egg mass formation, 60–90 min; and oviposition, about 120 min. The duration of oviposition is dependent on the size of the egg mass and varies from 5 to 20 min. At a 16-hr photoperiod all stages start 10 min earlier than at a 12-hr photoperiod. It is suggested that the effect of the photoperiod is achieved by a change of release activities of dorsal bodies and/or of CDC. The possibility that a nervous mechanism is involved in the control of the packaging of the egg cells is discussed.

Immunohistochemical indications of gastrin releasing peptide - bombesin-like immunoreactivity in the nervous system of the rat. Codistribution with substance P-like immunoreactive nerve terminal systems and coexistence with substance P-like immunoreactivity in dorsal root ganglion cell bodies

Weak to strong gastrin releasing peptide - bombesin (GRP-BN)-like immunoreaactivity was found in fine varicose nerve terminal systems of low to high densities in several parts of the CNS. The highest densities of strongly immunoreactive terminals were found in the marginal layer and in the substantia gelatinosa of the spinal cord, and in parts of the nuc. tractus spinalis nervi trigemini. Morphometrical analysis in the spinal cord demonstrates that GRP-BN-like-immunoreactive and substance P (SP), but not somatostatin (SS)-immunoreactive nerve terminals strikingly codistribute. Coexistence of SP and GRP-BN-like immunoreactivities was demonstrated in trigeminal and spinal ganglion nerve cells. Thus, GRP-BN-like immunoreactivity may coexist with SP in certain SP-immunoreactive nerve terminal systems.

Effects of substance P on adult rat sensory ganglion neurones in vitro

Intracellular recordings were performed in vitro from dorsal root ganglion cell bodies isolated from adult rats. A- and C-type cells were distinguished according to the conduction velocity at their axons. Pressure application of substance P from extracellular electrodes caused a depolarization of some cells. This depolarization was accompanied by changes in membrane resistance. These results suggest that the cell bodies of spinal ganglion cells of adult animals may possess substance P receptors.

Selective effects of apomorphine on dorsal raphe neurons: A cytofluorimetric study

Using a quantitative cytofluorimetric method to detect changes in the intracellular levels of serotonin (5-HT) in individual neurons in rat brain, we have found that the dopaminergic agonist apomorphine increases 5-HT content of dorsal raphe cell bodies without affecting cells in the median raphe nucleus. Liquid Chromatographic studies revealed that apomorphine also elevated the concentrations of both 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in striatum, the projection site for dorsal raphe neurons. Conversely, the dopaminergic antagonist haloperidol, at a dose of 0.8 mg/kg, decreased 5-HT levels in dorsal raphe cells. A lower dose of haloperidol (0.4 mg/kg), which had no significant effect alone, completely blocked the effect of apomorphine in the dorsal raphe. These results support the hypothesis that the effects of apomorphine on serotonergic neurons are secondary to dopamine receptor stimulation.

Mature spinal ganglion cells are not sensitive to opiate receptor mediated actions

Intracellular recordings were performed in vitro from dorsal root ganglion cell bodies isolated from adult rats. A- and C-type cells were distinguished according to the conduction velocity of their axons. Bath perfusion of normorphine, methionine-enkephalin (M-E) or [ d-Ala 2, d-Leu 5]-enkephalin (DADL) did not alter membrane potential, threshold potential for spike initiation or the spike waveform either before or after addition of Ba 2+ and 4-aminopyridine. Perfusion with γ-aminobutyric acid (GABA) depolarized A- and C-type cells and decreased input resistance. Picrotoxin antagonized this action. Morphine or M-E applied by perfusion never altered the GABA-induced depolarizations. Iontophoretically administered morphine reduced the GABA-induced depolarization without alteration of resting membrane properties or spike form, while M-E increased the GABA-induced depolarization. In about 50% of cells tested M-E applied iontophoretically produced a reversible hyperpolarization associated with an elevated input resistance (120–200% control). None of the effects produced by the opioids were antagonized by naloxone applied by perfusion or iontophoretically. These results suggest that the cell bodies of spinal ganglion cells of adult animals lack opiate receptors.

Effects of brain extracts on oocyte maturation in Helisoma (Pulmonata: Mollusca).

Normal oocyte development and the effects of brain extract injections on egg laying and on oocyte ultrastructure have been investigated in two populations of Helisoma: an egg-laying population (H. duryi) and a non-egg-laying, overwintering population (H. trivolvis). Oocyte development in H. duryi resembles that in other pulmonate molluscs. Endocytotic profiles occur in maturing oocytes but not in young (previtellogenic) oocytes. Injected horseradish peroxidase (HRP) and ferritin can be found in the follicular space and between follicle cells 2–3 h after injection. Ultrastructural evidence indicates that these tracers are taken up by maturing oocytes, but not by young oocytes or follicle cells. In non-egg-laying H. trivolvis large oocytes lack endocytotic profiles although a follicular space and many yolk granules may be present. Injection of extracts of dorsal bodies or suboesophageal ganglia from H. duryi induces egg laying in H. trivolvis within a few days. Injection of dorsal body extract into non-egg-laying animals also induces the appearance of many endocytotic profiles in large oocytes. It is suggested that endocytotic uptake of yolk components is stimulated by dorsal body extract in these animals.

Bilaterally situated dorsal raphe cell bodies have only unilateral forebrain projections in rat

Bilaterally situated dorsal raphe cell bodies have only unilateral forebrain projections in rat

Control of the activities of the neurosecretory light green and Caudo-Dorsal Cells and of the endocrine dorsal bodies by the lateral lobes in the freshwater snail Lymnaea stagnalis (L.)

Quantitative light and electron microscopical results indicate that in the freshwater snail Lymnaea stagnalis removal of the cerebral lateral lobes (LL), which are involved in the stimulation of reproduction and the retardation of body growth, results in inactivation of the neurosecretory Caudo-Dorsal Cells (CDC; stimulate ovulation) and the endocrine Dorsal Bodies (DB; stimulate female reproduction) and in activation of the neurosecretory Light Green Cells (LGC; stimulate body growth). These results support the hypothesis that the LL influence growth and reproduction by stimulating the CDC and DB and inhibiting the LGC. The possible way(s) in which the LL control these endocrine centers as well as the physiological significance of this control are discussed.

Simultaneous fluorescent retrograde axonal tracing and immunofluorescent characterization of neurons

A simple method is described for simultaneously double labeling single neurons with fluorescent retrograde axonal tracers and immunofluorescence using an antibody to serotonin. Caudata-putamen injection of orange fluorescent propidium iodide, in particular, proved effective in retrogradely labeling dorsal raphe cell bodies. These same perikarya could be stained green with the indirect immunofluorescent method, using green fluorescent fluorescein isothiocynate (FITC) as the second antibody.

Enkephalin inhibits release of substance P from sensory neurons in culture and decreases action potential duration.

Sensory neurons grown in dispersed cell culture in the absence of non-neuronal cell types contain immunoreactive substance P that is chemically similar to synthetic substance P. When depolarized in high-K+ media (30-120 mM), the neurons release this peptide by a Ca2+-dependent mechanism. An enkephalin analogue, [D-Ala2]enkephalin amide, at 10 micron inhibits the K+-evoked release of substance P. At the same or lower concentrations, [D-Ala2]enkephalin amide and enkephalin decrease the duration of the Ca2+ action potential evoked and recorded in dorsal root ganglion cell bodies without affecting the resting membrane potential or resting membrane conductance. This modulation of voltage-sensitive channels may account for the inhibition of substance P release.

Toxic effects of adriamycin on the ganglia of the peripherial nervous system: a neuropathological study.

Rats were injected intravenously with 10 mg/kg of adriamycin (doxorubicin). All the treated animals developed severe posterior limb ataxia on days 11 and 12 following the injection. Mild ataxia of the forelimbs was noted later. The animals were killed between days 10 and 50. Light microscopy revealed changes in ganglion cells of the peripheral nervous system with sparing of neurons in the central nervous system. In the spinal, paravertebral and trigeminal ganglia, necrosis of neurons was followed by mild lymphocytic infiltration, and ultimate loss of ganglion cells, and a marked proliferation of nerve sheath cells. Electron microscopic study revealed increased numbers of neurofilaments and the presence of membrane-bound cisterns in the affected dorsal root ganglion cell bodies. It is concluded that adriamycin, an important anticancer therapeutic agent, has neurotoxic properties and that it selectively damages the ganglia of the peripheral nervous system.