Role of the visceral nerve in heart rate variations during different behavioral patterns in Megalobulimus sanctipauli (mollusca,gastropoda, pulmonata)

• 1.1. The role of the visceral nerve in mediating the changes in heart rate associated with different behavioral patterns was investigated in Megalobulimus sanctipauli.
• 2.2. The results of acute and chronic denervation experiments indicate that the visceral nerve has no excitatory or inhibitory tonic action on the heart of snails retracted into the shell, nor does it account for the increase in heart rate associated with the locomotion and feeding behaviors.
• 3.3. These changes in heart rate are, probably, indirect effects of increased activity such as an increase in venous return.
• 4.4. The visceral nerve is responsible for approximately 3/4 of the increase in heart rate associated with the first minute of extrusion.
• 5.5. The small increase in heart rate observed in denervated animals is probably caused by an increase in venous return generated by muscle activity that forces the head and food out of the shell.

     

Organ specific changes in energy metabolism due to anaerobiosis in the sea mussel Mytilus edulis (L.)

• 1.1. Anaerobic energy metabolism was investigated in different organs of Mytilus edulis and the whole animal.
• 2.2. Succinate accumulates to high levels in most organs but remains low in the hemolymph.
• 3.3. After 16 hours propionate accumulation is observed in all organs. Experimental evidence is not sufficient yet to point out organs that produce more propionate than others.
• 4.4. Acetate is a minor end product.
• 5.5. Acetate and propionate are found in the hemolymph in amounts equal to those in the organs.
• 6.6. Animals incubated in oxygen-free seawater accumulate more end products than animals exposed to air, in the form of volatile fatty acids that are excreted into the incubation water.
• 7.7. Alanine and glutamine increase in the posterior adductor muscle. Aspartate decreases in the total animal, posterior adductor muscle and gills, while in the hemolymph decrease in alanine, asparagine, serine, threonine and proline are observed.

     

Neurotransmitters of cephalopods

1. ACh, dopamine, noradrenaline, 5-HT,l-glutamate, and GABA are widely distributed in cephalopods and probably all function as neurotransmitters; octopamine also occurs and at one site is known to act as a neuromodulator.
2. Several peptides are also present, as well as nitric oxide synthase.
3. In the brain and sense organs cholinergic, aminergic, serotonergic and glutamatergic systems seem to be the most important.
4. ACh is also active in the gut, vascular system and some body muscles: it is generally inhibitory. The ACh receptors are similar to the vertebrate nicotinic type.
5. The catecholamines are important in the gut and vascular system: they are generally excitatory. The NA receptors are like the α-adrenergic subtype of vertebrates, but the nature of the DA and OA receptors is less certain.
6. 5-HT is important in the gut but is endogenous in some chromatophore nerves and acts on receptors that seem like the vertebrate 5-HT₁ type.
7. l-glutamate is an excitatory transmitter at the chromatophore (and probably at other) nerve-muscle junctions and is an extremely strong candidate for being the excitatory transmitter at the squid giant synapse. There are NMDA receptors on Schwann-cells but the receptors on neurons and muscles are like the vertebrate kainate type.
8. Little is known about the mode of action of cephalopod peptides; nor has it ever been shown that they co-exist with conventional transmitters in these animals.
9. The structure of one (FMRFamide) receptor has been elucidated, but apart from this nothing is known of the molecular biology of receptors in cephalopods.

     

Discharge patterns of lagenar and saccular neurones of the goldfish eighth nerve: Displacement sensitivity and directional characteristics

• 1.1. The responses of goldfish lagenar and saccular neurones were analyzed for underwater sound stimulation and head vibration in three orthogonal directions.
• 2.2. Both organs show similar sound pressure and displacement sensitivity below 200 Hz, and respond to a motional stimulus component at 100 Hz.
• 3.3. Calculated directions of best sensitivity in the saggital and horizontal planes correspond with hair cell orientation maps.
• 4.4. Stimulus-response phase-angles correspond only roughly with the patterns to be expected from a simple model for hair cell stimulation.
• 5.5. Variation in the degree of coupling between hair cell cilia and the otolith, and complex three-dimensional relative motion patterns probably occur in both organs.

     

Calcium binding by sarcoplasmic reticulum and mitochondria isolated from an annelid visceral muscle in relation to whole muscle calcium influx and efflux

• 1.1. Nereis pharangeal visceral muscle is composed of obliquely striated fibres with low mitochondrial density and moderately developed sarcoplasmic reticulum.
• 2.2. Isolated mitochondria and sarcoplasmic reticulum showed moderate passive calcium binding but only low ATP-promoted calcium binding which was inhibited by caffeine.
• 3.3. Whole fibres preloaded with Ca⁴⁵ showed a two compartment efflux. The slow, presumably intracellular, compartment accounted for only 10% of total Ca⁴⁵ activity.
• 4.4. Both acetylcholine and high KCl treatments stimulated calcium influx, causing contractures while calcium-free and EGTA treatments inhibited both these contractures and normal spontaneous contractions.
• 5.5. Lanthanum inhibited normal contractility and KCl contractures. Lanthanum also inhibited Ca⁴⁵ influx but was without effect on Ca⁴⁵ efflux.
• 6.6. It is concluded that there is little calcium storage capacity in these visceral muscle fibres and that normal contractions are strongly dependent upon extracellular calcium influx.

     

Analysis of peptide biosynthesis in the neurointermediate lobe of Xenopus laevis using high-performance liquid chromatography: occurrence of small bioactive products

• 1.1. Ppeitde biosynthesis in neurointermediate lobes of black adapted Xenopus laevis was studied using pulse-chase incubation and reversed-phase, high-performance liquid chromatographic analysis.
• 2.2. During the pulse period one major product was synthesized, which was subsequently converted to 12 chase peptides, suggesting a precursor-product mode of biosynthesis for this tissue.
• 3.3. Chase peptides I, II and IV possessed high melanotropic activity. Alpha-MSH did not appear to be among the chase peptides. Peptide II had also high corticotropic activity.
• 4.4. Peptides I and II are probably small, since they were TCA-soluble and ran faster on acid-urea gels than α-MSH. They may, however, well be structurally related to this latter hormone.

     

Heart rates of adult red-spotted newts,Notophthalmus viridescens in air and submerged in normoxic and hypoxic water at different temperatures

• 1.1. Heart rates of adult aquatic red-spotted newts can be conveniently recorded using an impedance pneumograph.
• 2.2. Heart rates decrease linearly with decreasing temperature.
• 3.3. Submergence in normoxic and hypoxic water at 10°, 15°, and 20°C results in bradycardia which is more pronounced in hypoxic water.
• 4.4. At 5°C one newt exhibited the above pattern, but bradycardia was not exhibited by the other newt during normoxic submergence.
• 5.5. Diminishing heart rates are probably due to oxygen deficiency, not immersion alone.
• 6.6. Recovery from bradycardia in air is rapid and not linked with resumption of aerial breathing.

     

Varying amounts of stretch stimulus regulate stretch-induced muscle hypertrophy in the chicken

• 1.1. The effects of different amounts of passive stretch per day and number of days of stretch on muscle hypertrophy in the chicken patagialis (PAT) muscle were determined.
• 2.2. Stretch for 24 hr per day (h/d) resulted in a more rapid hypertrophy both on a wet and dry tissue basis (P < 0.001) than stretch for 4 h/d.
• 3.3. Stretch increased PAT weight 43% and 25% in 24 h/d and 4 h/d treatments, respectively, after 10 days of stretch, but by day 25 of stretch there was no difference between treatments.
• 4.4. In a second experiment, the PAT muscle was hypertrophied and then the effects of intermittent stretch (4 h/d) on regression of hypertrophy (muscle atrophy) were investigated.
• 5.5. Intermittent stretch (4 h/d) for 5 and 10 d significantly (P < 0.001) inhibited regression of hypertrophied muscle.
• 6.6. The results of the present study indicate that stretch-induced hypertrophy can be modulated by varying the amount of stretch applied per day.
• 7.7. Intermittent stretch can be used to inhibit the regression which occurs when a continuous stretch stimulus is removed.
• 8.8. Intermittent stretch is a useful model for investigating mechanisms of muscle hypertrophy and inhibition of muscle atrophy.

     

Sex differences in vascular reactivity to adrenergic agents in the rat

• 1.1.The study was designed to determine if there are sex-dependent differences in vascular reactivity to adrenergic agents.
• 2.2.Vascular reactivity of both aortic and tail artery smooth muscle from male and female rats to various vasoactive agents was assessed. 3.li]The vascular response of aortic smooth muscle to both phenylephrine and isoproterenol were significantly greater in male rats as compared to females.
• 3.4.There were apparent sex differences in responsiveness to the KCl-induced, non-receptor mediated contraction of aortic smooth muscle in that the sensitivity to KCl was enhanced in male rats.
• 4.5.No sex differences were observed in tail artery preparations.
• 5.6.Phentolamine reduced the maximal tension induced by KCl in the tail artery but not aortic artery preparations. This effect was not sex dependent.
• 6.7.No differences in the vascular smooth muscle responsiveness to acetylcholine or sodium nitrate was observed between groups or within different vascular beds.
• 7.8.The increased sensitivity of males to adrenergic challenge could explain in part some of the existing sex differences in cardiovascular disease and hypertension.

     

Proteolysis post mortem in North Atlantic krill

• 1.1. The autoproteolytic processes in selected species of North Atlantic krill, Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Krøyer) and T. raschii (M. Sars) have been examined at 0°C by following the release of peptides and free amino acids.
• 2.2. The krill contains high levels of peptide hydrolases, and autoproteolysis seems to be due mainly to digestive enzymes localized in the hepatopancreas and the intestinal tract of the animals.
• 3.3. During autoproteolysis the individual amino acids were generally released at rates corresponding to their proportion in the bulk protein of the krill. The major exceptions were alanine which accumulated in amounts larger than was to be expected from the composition of the krill protein, and glutamic acid/glutamine, aspartic acid/asparagine, arginine, and to some extent glycine, proline and serine, which accumulated to a lesser extent than was to be expected.
• 4.4. Storage of krill for 1 week resulted in only minor changes in the total content of amino acids as determined after acid hydrolysis, with the exception of alanine which increased in concentration.
• 5.5. The results suggest that the formation of free alanine is partly due to reactions other than proteolysis.
• 6.6. The release of free amino acids was accompanied by a considerable increase in the amount of small peptides, and glutamic acid/glutamine, aspartic acid/asparagine, glycine and proline tended to accumulate in these peptides.
• 7.7. The autoproteolytic activity of the Thysanoessa species showed seasonal variations, probably in response to food availability. In the case M. norvegica, the results suggest that there are smaller fluctuations in the level of proteolytic enzymes, probably indicating less pronounced variations in the food intake over the year.

     

Seasonal changes of lipids and fatty acids in oyster tissues (Crassostrea virginica) and estuarine particulate matter

• 1.1. Lipid concentration in adductor muscle ranged from 2–68, in visceral mass from 5–28, in mantle and gill from 5–20 and in heart from 27.8–79 mg/g wet tissue. Particulate matter lipids varied from 1.0–2.6 mg/1 of estuarine water.
• 2.2. Neutral and polar lipids ranged from 25–38% of the total lipids in the oyster tissue and from 62–75% of the estuarine particulate organic matter.
• 3.3. Seasonal maxima of lipid concentrations varied among oyster tissues. Peak particulate lipids occurred in November.
• 4.4. It is proposed that seasonal variation in oyster lipids was more related to reproductive cycles than to food lipid supply.

     

Lactate dehydrogenase of goldfish red and white muscle in relation to thermal accumulation

• 1.1. Activities of the red and white muscle LDH from 8°C-acclimated goldfish were about three times higher than those acclimated to 28°C.
• 2.2. Isozyme composition and some kinetic properties of the red muscle LDH differed from those of the white muscle enzyme.
• 3.3. The amount of red muscle as well as LDH activity tended to increase during cold acclimation.

     

Domain structure of the 90-kDa stress protein: Heparin- and antibody-binding domain

• 1.1. To understand the physiological roles of the 90-kDa stress protein (HSP90), we investigated the heparin- and antibody-binding domains of the protein.
• 2.2. For heparin-binding sites, HSP90 was digested completely with trypsin, and the digests were applied to a heparin-Sepharose column and eluted with 1.0 M NaCl, followed by 8.0 M urea.
• 3.3. Each elutant was purified by a reverse-phase C₁₈ column.
• 4.4. Two peptides from the NaCl-eluted fraction and no peptide from the urea-eluted fraction were purified.
• 5.5. The purified peptides were sequenced by an automated peptide sequencer.
• 6.6. One of the heparin-binding sites was present between Leu-362 and Arg-365; another was present between Leu-645 and Lys-648.
• 7.7. These two peptides were basic and considerably hydrophilic.
• 8.8. For antibody-binding sites, HSP90 was mildly digested with trypsin, electrophoresed on SDS-polyacrylamide gels and transferred to PVDF membranes.
• 9.9. The four bound of the trypsin fragments could be sequenced with a peptide sequencer.
• 10.10. There was only one antibody-binding peptide, 38 kDa, starting from Pro-2. The others showed no cross-reactivity with the antibody and started from Leu-283.
• 11.11. Therefore, the epitopes of HSP90 are present between Pro-2 and Leu-282.
• 12.12. The heparin-binding sites are present from the middle region of the HSP90 molecule, and the antigen sites are at the N-terminal domain.

     

Carbonic anhydrase III content in various equine muscles

• 1.1. In this study, carbonic anhydrase III (CA-III) content in 18 equine muscles was determined by enzyme immunoassay.
• 2.2. It was found to differ in several muscles.
• 3.3. That in external intercostal muscle, rectus abdominis muscle and splenius muscle from four horses was very high.
• 4.4. Although the masseter muscle had only type I fibers, CA-III content was similar to that in mixed-fiber type muscles such as the biceps femoris muscle.
• 5.5. It thus appear that equine type I fibers can be further subgrouped.

     

Sulphhydryl protease inhibitors from pineapple plant stem

• 1.1. Pineapple stem extract, consisting of a mixture of the protease bromelain and sulphhydryl protease inhibitors, was fractionated by gel permeation chromatography.
• 2.2. Inhibitor-containing fractions were further resolved by ion exchange chromatography on DEAE-cellulose, giving 12 chromatographically distinct inhibitory fractions.
• 3.3. These 12 inhibitory fractions all show an inhibition specificity towards bromelain.
• 4.4. Reduction, S-carboxymethylation and refractionation of each of these inhibitory fractions gave, for each fraction, two separated peptides of ca 13 and 40 amino acids in length, respectively.
• 5.5. The amino acid compositions and the N-terminal sequences of these peptides show the inhibitors to be a closely homologous set. Both the constituent peptides of each fraction are microheterogeneous. Each DEAE-cellulose chromatogram peak contains a co-eluting set of iso-inhibitors.
• 6.6. Structural microvariations within these isoinhibitors have a minor influence on inhibitor activity towards bromelain.

     

Presynaptic modulation of sensory afferents in the invertebrate and vertebrate nervous system

• 1.1. Ultrastructural examination of the central terminals of sensory afferent neurons in both invertebrates and vertebrates demonstrates that the synapses that form the substrate for presynaptic inhibition and facilitation are almost universally present.
• 2.2. Presynaptic modulation of afferent input acts in many ways which tailor the inflow of sensory information to the behaviour of the animal, effectively providing a means of turning this on and off, or of combining information of the same or different modalities to refine responsiveness or clarify ambiguity.
• 3.3. Presynaptic modulation may act in several different roles on the same afferent.
• 4.4. A comparison of the mechanisms of presynaptic inhibition in different animals demonstrates the likelihood of a variety of common mechanisms,several of which may act simultaneously on the same terminal.These include changes in the conductance of the afferent membrane to Cl^-, K⁺and Ca²⁺ions, in addition to less well understood mechanisms that directly affect transmitter release.
• 5.5.A single transmitter can produce several effects on a terminal through the same or different receptors.
• 6.6. Ultrastructural studies of afferent terminals reveal that only a proportion of boutons on a given afferent may receive presynaptic input and that this may depend on the region of the nervous system in which these are found or on the identity of the postsynaptic neurons contacted.
• 7.7. The synaptic relationships of afferent terminals can be complex. In invertebrates different types of presynaptic neuron may interact synaptically,as may postsynaptic dendrites in vertebrates.
• 8.8. Axons presynaptic to afferent terminals in vertebrates frequently synapse also with dendrites postsynaptic to the afferents.
• 9.9. In both invertebrates and vertebrates reciprocal interactions between afferents and postsynaptic neurons are seen.
• 10.10. Ultrastructural immunocytochemistry reveals the likely dominance of GABA as an agent of presynaptic inhibition but also demonstrates the possible presence of other transmitters some of whose roles are less completely understood.

     

Axonal mapping of neurosecretory Helix bursting cells. Functional aspects of peripheral multibranched axons

• 1.1. The peripheral axon distribution from two bursting neurons was investigated using electrophysiological methods. Both of these cells send out a bundle of axon branches which goes via the visceral nerve to the heart and in the uterine nerve.
• 2.2. The relative number of axon branches in the two nerves was determined through double-shock experiments.
• 3.3. The axon bundle takes the visceral nerve and its uterine branch, supplying the effector systems in parallel.
• 4.4. Slight differences in conduction velocity between the axon branches produce an enlargement of the efferent volley.
• 5.5. The number of active axon branches conveying orthodromic or antidromic spikes is controlled by inhibitory potentials converging onto the initial part of the bundle, so that the two bursting cells amount to a pool of 35 to 40 interconnected nerve cells.
• 6.6. The atypical axonal distribution of the two bursting cells might be related to their neurosecretory properties.

     

PACAP and Other Neuropeptide Targets Link Chronic Migraine and Opioid-induced Hyperalgesia in Mouse Models*

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Highlights

• •Characterized the peptides involved in migraine and opioid-induced hyperalgesia (OIH).
• •Identified more than 1500 peptides in seven nervous system regions.
• •Discovered seven peptides significantly changed with migraine and nine with OIH.
• •Validated PACAP involvement in both conditions via pharmacological studies.

     

AMP-deaminase from human skeletal muscle. Subunit structure,amino-acid composition and metal content of the homogenous enzyme

• 1.1. Homogenous human skeletal muscle AMP-deaminase was obtained by chromatography on phosphocellulose.
• 2.2. Native enzyme molecular weight was 290,000, while a value of 71,000 was found for the subunit molecular weight.
• 3.3. No distinct differences were found in amino-acid composition of human skeletal muscle AMP-deaminase as compared with other vertebrate enzymes.
• 4.4. Human muscle AMP-deaminase contains about 2g-atom of zinc per 280,000; considerable amounts of calcium and magnesium were also found.

     

Further study of effects of synthetic peptides on identifiable giant neurones of an african giant snail (Achatina fulica Férussac)

• 1.1. Effects of the following peptides at 10⁻⁴ M on identifiable giant neurones of Achatina fulica Férussac were examined: physalaemin, eledoisin, bradykinin, neurokinin A, neurokinin B, neuromedin B, gastrin releasing peptide decapeptide (neuromedin C), gastrin releasing peptide (14–27), cholecystokinin tetrapeptide, cholecystokinin octapeptide, thyrotropin releasing hormone, Arg-vasotocin, γ-melanocyte stimulating hormone.
• 2.2. The six neurones tested were as follows: PON (periodically oscillating neurone), TAN (tonically autoactive neurone), RAPN (right anterior pallial neurone), d-RPLN (dorsal-right parietal large neurone), VIN (visceral intermittently firing neurone) and d-VLN (dorsal-visceral large neurone).
• 3.3. Of the peptides examined, only Arg-vasotocin at 10⁻⁴ M produced the excitatory effects on PON, VIN and d-VLN. Physalaemin showed slight inhibitory effects on TAN; this substance was sometimes almost ineffective on the neurone.
• 4.4. The other peptides examined were completely ineffective on all of the neurones tested.