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1.
The effects of proctolin (RYLPT) on neurally evoked contractions of locust oviduct muscle were studied to examine the role of proctolin as a cotransmitter. Increasing the number of stimuli in a burst (from one to 30 stimuli) resulted in an increase in amplitude of contraction of locust oviduct muscle. Proctolin was capable of increasing the amplitude of neurally evoked contractions at lower-stimulus regimes (one- and two-stimulus bursts) but did not do so at higher-stimulus regimes (five- and 10-stimulus bursts). The effects of proctolin were dose dependent within the one- and two-stimulus regimes, with thresholds at 10−9 M and maxima at 2.5 × 10−8 M. Addition of proctolin increased the basal tonus and size of a postcontraction relaxation of the oviduct muscle in a dose-dependent manner during all stimulus regimes. However, the effect of proctolin on basal tonus and the postcontraction relaxation was much less at the higher stimulus regimes. Previously, several proctolin analogues have been tested for their ability to antagonize proctolin-induced contractions of the oviduct muscle. Since proctolin is proposed to be a cotransmitter at this neuromuscular junction, one of these analogues, cycloproctolin, was used to antagonize proctolin's effects on neurally evoked contractions. In the presence of the antagonist, the maximum amplitude induced by application of proctolin was decreased by 22.7%, while the proctolin-induced increase in basal tonus was decreased by 45.8%. Finally, the maximum increase in the size of the postcontraction relaxation caused by proctolin was lowered by 32.0%. The results of the present study show that exogenously applied proctolin is an excitant of the oviduct muscle at lower, rather than higher, stimulus regimes, and this latter inaction may be due to the corelease of endogenous proctolin during increased neural stimulation. © 1997 John Wiley & Sons, Inc. J Neurobiol 33: 139–150, 1997 相似文献
2.
C Mazzocco-Manneval M Kuczer D Konopinska B Fournier B.G Loughton J Puiroux 《Peptides》1998,19(10):1641-1651
Proctolin (Arg-Tyr-Leu-Pro-Thr) and proctolin analogs modified at position 1, 2, or 5 caused dose dependent contractions of Blaberus fore- and hindgut. The varying contractile effects between both tissues revealed the possible presence of receptor subtypes as identified by [GABA1]-proctolin. A single population of binding sites (Kd ≈ 100 n
) was deduced from Scatchard analysis. In addition, nanomolar concentrations of proctolin induced a dose-dependent hydrolysis of phosphoinositides (PIns) augmented by GTPγS (1 μ
) on foregut membranes but no accumulation of cAMP. Proctolin induced contractions are likely mediated via a phospholipase C linked to a heptahelical receptor bound to heterotrimeric G-proteins. 相似文献
3.
Grzegorz Rosiński Ignacy Korczyński Małgorzata Słocińska Robert Kuźmiński 《Insect Science》2011,18(2):160-165
Abstract The peptides proctolin, crustacean cardioactive peptide (CCAP) and FMRFamide, which are known to modulate insect muscle contractions, were assayed for their action on oviduct contractions in Hylobius abietis. A video microscopy technique and computer‐based method of data acquisition and analysis were used to investigate the effects of theses peptides on spontaneous contractions of continuously perfused oviducts. All three peptides tested stimulate spontaneous contraction activity of the pine weevil oviduct, increasing the frequency and amplitude of phasic contractions in a dose‐dependent manner. Proctolin is more potent as a stimulator than CCAP. For proctolin a threshold response of oviduct muscles is at concentration of peptide 10?11–10?10 mol/L and for CCAP at concentration range 10?10–10?9 mol/L. FMRFamide exerts a weak stimulatory effect on the oviduct, and at higher concentrations of the peptide (above 10?8 mol/L). The peptides exert different responses on oviduct contractions and they may play a role as functional regulators in such processes as egg movement and oviposition. 相似文献
4.
Jacques Puiroux Anne Pedelaborde Barry G. Loughton 《Insect biochemistry and molecular biology》1992,22(8):859-865
The binding of [3H]proctolin to oviduct membranes has been analyzed to investigate the nature of proctolin binding sites in the oviduct. Proctolin binding was found to be time dependent, proportional to concentration of membrane protein, saturable, specific and reversible. Two apparent proctolin binding sites were recognized. The first had a Kd of 400 ± 82 nM and a Bmax of 23.7 ± 6.7 pmol/mg protein. The second had a Kd of 2.4 ± 0.2 μM and a Bmax of 96.3 ± 16.7 pmo/mg protein.
Binding was specific in thatcompetition experiments with a wide range of peptides showed that only Arg-Tyr-Leu-Pro-Ala was an effective competitor at μM concentrations. All other peptides examined weekly reduced proctolin binding at concentrations above 50 μM. Certain peptides were found to potentiate [3]pproctolin binding at low μM concentrations (1–10 μM) and to inhibit proctolin binding at higher concentrations. The significance of these findings is discussed. 相似文献
5.
Proctolin has been isolated from oviduct extracts of Leucophaea maderae by HPLC. Quantitative bioassay with the hindgut of L. maderae demonstrated a proctolin titre of 0.93 +/- 0.15 ng/oviduct. Exposure to proctolin produced three changes in the spontaneous contractile activity of the oviduct: an increase in muscle tonus, an increase in the amplitude and frequency of phasic contractions. The sensitivity of the oviduct to proctolin was compared with the hindgut and foregut organ preparations from the same insect. Oviducts were responsive to proctolin in a calcium-free medium and the peptide also appeared to facilitate the reentry of calcium after depleted preparations were returned to normal levels of external calcium. 相似文献
6.
We have developed a semi-intact preparation-consisting of an isolated oviduct with abdominal ganglia VII and VIII intact and attached-with which to characterize the effects on oviduct contraction, of peptides that are bath applied to CNS tissues. The work presented here offers a qualitative analysis of the central effects of SchistoFLRFamide and proctolin upon action potentials recorded from the oviducal nerves and upon oviduct contraction. In the process of this, we hope to demonstrate that a previously characterized putative CNS SchistoFLRFamide receptor [Peptides 23 (2002) 765] is a functional receptor.SchistoFLRFamide (10(-6)M), bath applied to abdominal ganglion VII, caused an increase in action potential frequencies recorded from the oviducal nerves, as well as an increase in the frequency of phasic contractions of the oviduct. Although the function of this response is not known, these results further support the possibility that the putative CNS SchistoFLRFamide receptors are functional receptors.Proctolin (10(-6)M), bath applied to abdominal ganglion VIII, altered the rhythmic bursting of action potentials recorded from the oviducal nerve and changed the appearance and cycle duration of neurogenic oviduct contractions. 相似文献
7.
Angela B. Lange Ian Orchard William Lam 《Archives of insect biochemistry and physiology》1987,5(4):285-295
Proctolin increases the frequency and amplitude of myogenic contractions and results in a sustained contraction of the oviducts of Locusta migratoria. The possible mode of action of proctolin receptors on this visceral muscle has been investigated. Calcium-free saline, containing either 20 mM magnesium ions or 100 μM EGTA, inhibited myogenic contractions, lowered basal tension, and abolished all the effects of proctolin following a 20 min incubation. These effects were reversible upon washing with normal saline. Similar results were obtained with normal saline containing 10 mM cobalt ions. Nifedipine at 50 μM lowered basal tension, abolished myogenic contractions, and reduced the proctolin-induced sustained contraction by 42-62% at 0.5 nM proctolin and by 33-37% at 5 nM proctolin. Similar results were obtained with 100 μM verapamil. Proctolin was still capable of eliciting considerable contractions (25-67% of controls) in preparations depolarized with 100 mM potassium saline. The removal of calcium from the high-potassium saline reversibly abolished the potassium-induced contraction and reversibly blocked the action of proctolin. Nifedipine was ineffective in blocking the action of proctolin in high-potassium saline. Neither cyclic AMP levels nor cyclic GMP levels of the lateral oviducts were elevated by proctolin in the presence of a phosphodiesterase inhibitor. The results indicate that proctolin mediates its effects via an influx of external calcium ions. This calcium appears to enter through two channels, a voltage-dependent channel and a receptor-operated channel. Cyclic nucleotides do not appear to be involved in the action of proctolin in this visceral muscle. 相似文献
8.
ABSTRACT. A delicate lace-like membrane covers the ovaries of Tabanus sulcifrons. These membranes were found to contain muscle fibres that provide the organs with motile properties. The lateral oviducts consist of a single layer of longitudinal muscles that form a structural syncytium by means of an extensive anastomosis of the fibres comprising it. The common oviduct is composed of two muscle layers, an outer sheath of circular muscle and an inner substratum of longitudinal muscle. Both of these layers showed evidence of a structural syncytium. When isolated in saline, the oviduct was spontaneously active and gave a simple phasic pattern of contraction. Such muscle preparations were sensitive to both 5-hydroxytryptamine (5HT) and the insect myotropic peptide, proctolin. Excitation was generally indicated by a rise in muscle tonus or an increase in the frequency and amplitude of individual phasic contractions, or all three characteristics. The threshold for activation with 5HT was variable, ranging from as low as 4 × 10-9 M to 1 × 10-7 M. Proctolin evoked a noticeable increase in the tonus of most oviducts at 10-10 M. However, several preparations responded to as little as 3 × 10-11 M proctolin. 相似文献
9.
M. A. Saver J. L. Wilkens C. N. Airriess 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(7):473-482
The decapod crustacean heartbeat is initiated by the cardiac ganglion and is regulated by a variety of neuronal and hormonal
inputs. In this paper we examine the effects of the peptide hormone proctolin which appears to have multiple sites of action
in the shore crab, Carcinus maenas. To examine some of the potential sites of proctolin action we used three heart preparations: in situ intact and open hearts,
and isolated hearts. We provide evidence in support of the hypothesis that proctolin affects cardiac activity at many levels.
It acts at the cardiac ganglion to modulate burst rate and at the myocardium to alter contractile force. We calculated the
relationship between contractility and ganglionic output of in situ hearts as the ratio of ventricular pressure or tension
to amplitude of the electromyogram or intracellular excitatory junction potential. Large proctolin-induced changes in this
ratio, which could not be accounted for by ganglionic output, membrane potential or input resistance suggest direct action
on the myocardium. The greater increases in ventricular pressure than in tension in the in situ hearts may reflect proctolin-induced
contraction of the cardioarterial valves. Finally, proctolin can possibly influence heart rate by action on the cardioregulatory
nerves of the central nervous system.
Accepted: 11 May 1998 相似文献
10.
Both octopamine and proctolin potentiate nerve-evoked skeletal muscle contractions in the horseshoe crab, Limulus. The threshold concentration for octopamine was 10?9 to 10?8M, while for proctolin it was 3 × 10?9M. Norepinephrine and dopamine produced effects similar to octopamine but at higher thresholds; tyramine and serotonin were ineffective. Octopamine caused significant increases in amplitudes of excitatory postsynaptic potentials (epsps) of muscle fibers, but had little effect on muscle fiber input resistance or membrane potential. Also, octopamine did not affect depolarization of muscle fibers and subsequent contraction due to the direct action of exogenously applied glutamate. These results suggest that octopamine potentiates nerve-evoked contractions primarily by facilitating release of neuromuscular transmitter. At concentrations above 10?7M, however, octopamine sometimes caused muscle spikes in response to motoneuron stimulation, a finding that suggests that octopamine may also have some postsynaptic action. Proctolin potentiated the muscle contractions evoked by glutamate but had little effect on glutamate-evoked muscle fiber depolarization, muscle fiber input resistance, or membrane potential. Thus, proctolin appears to act directly on skeletal muscle to enhance contractility. The proctolin-induced potentiations of contraction were sometimes accompanied by modest increases in epsp amplitude, so that unlike lobster skeletal and Limulus cardiac neuromuscular preparations, proctolin may have a secondary direct synaptic effect. Both octopamine and proctolin have been found in Limulus cardiac ganglion. This potential access to the hemolymph and the relatively low threshold concentrations needed for physiological action suggest that octopamine and proctolin could function as hormonal modulators of neuromuscular function in Limulus. 相似文献
11.
Proctolin is a pentapeptide (arg-tyr-leu-pro-thr) found in nervous tissues throughout the phylum Arthropoda. Initially described as a peptidergic neuromuscular transmitter, it now appears that proctolin is a major arthropod neurohormone modulating nervous activity, muscle tonus and contractile force. Structure-function studies with synthetic analogues demonstrate diverse peptides which retain agonistic activity, but few exhibit a high degree of affinity for the cockroach hindgut receptor compared with proctolin (Kdapp = 2 x 10(-8) M). High affinity agonists (Kdapp less than or equal to 10(-7) M) are limited to [phe2]-proctolin, [lys1]-proctolin and specific N-terminal additions. In this regard the hindgut receptor differs in its ligand specificity from that reported for the locust extensor tibia receptor. Using the analogue studies to predict sequences which may act as agonists, we have examined the known vertebrate peptide hormones for proctolin-like sequences. A possible relationship between vasoactive intestinal peptide, proctolin and erythrophore concentrating hormone is critically evaluated. 相似文献
12.
Locustatachykinin III and IV: two additional insect neuropeptides with homology to peptides of the vertebrate tachykinin family 总被引:5,自引:0,他引:5
L Schoofs G M Holman T K Hayes J P Kochansky R J Nachman A De Loof 《Regulatory peptides》1990,31(3):199-212
Two myotropic peptides termed locustatachykinin III and IV were isolated from 9000 brain-corpora cardiaca-corpora allata-suboesophageal ganglion extracts of the locust, Locusta migratoria. The primary structures of Lom-TK III and IV were established as amidated decapeptides: Ala-Pro-Gln-Ala-Gly-Phe-Tyr-Gly-Val-Arg-NH2 (Lom-TK III) and Ala-Pro-Ser-Leu-Gly-Phe-His-Gly-Val-Arg-NH2 (Lom-TK IV). The locustatachykinins were synthesized and shown to have chromatographic and biological properties identical with those of the native materials. They stimulate visceral muscle contractions of the oviduct and the foregut of Locusta migratoria and of the hindgut of Leucophaea maderae. Both peptides exhibit sequence homologies with the vertebrate tachykinins. Sequence similarity is greater with the fish and amphibian tachykinins (up to 40%) than with the mammalian tachykinins. In addition, the intestinal and oviducal myotropic activity of the locustatachykinins is analogous to that of vertebrate tachykinins. Both chemical and biological similarities of vertebrate and insect tachykinins substantiates the evidence for a long evolutionary history of the tachykinin peptide family. 相似文献
13.
The biogenic amine octopamine and the pentapeptide proctolin are two important neuroactive chemicals that control contraction of the oviducts of the African locust Locusta migratoria. The physiological responses and signal transduction pathways used by octopamine and proctolin have been well characterized in the locust oviducts and this therefore provides the opportunity to examine the interaction between these two pathways. Octopamine, via the intracellular messenger adenosine 3',5'-cyclic monophosphate (cyclic AMP), inhibits contraction of the oviducts, while proctolin, via the phosphoinositol pathway, stimulates contraction. We have examined the physiological response of the oviducts to combinations of octopamine and proctolin and also looked at how combinations of these affect one of the main intracellular mediators of the octopamine response, namely cyclic AMP. It was found that application of octopamine to the oviducts led to a dose-dependent reduction in tonus of the muscle and also a decrease in the amplitude and frequency of spontaneous phasic contractions. Octopamine-induced relaxation was enhanced in the presence of the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX). Octopamine was also able to inhibit proctolin-induced contractions of the oviducts in a dose-dependent manner. A 10(-9) M proctolin-induced contraction was inhibited by 83% in the presence of 10(-5) M octopamine, and was completely inhibited in the presence of 10(-5) M octopamine plus 5x10(-4) M IBMX. Octopamine led to a dose-dependent increase in cyclic AMP content as measured by radioimmunoassay. In the presence of 10(-9) M proctolin, this octopamine-induced increase in cyclic AMP was reduced by as much as 60%. Proctolin also caused a dose-dependent decrease in the cyclic AMP elevation produced by 5x10(-6) M octopamine. These results indicate that octopamine and proctolin can antagonize each other's physiological response when added in combination, and that proctolin is able to modulate the response of the oviducts to octopamine by influencing cyclic AMP levels. 相似文献
14.
- 1.1. Proctolin and a second myotropic peptide were extracted from the hindgut of the cockroach Leucophaea maderae with methanol-water-acetic acid (90:9:1). The two peptides were easily separated by HPLC on a μ-Bondapak-phenyl column.
- 2.2. Like proctolin, the second peptide was heat stable and was inactivated by the exopeptidases aminopeptidase M and carboxypeptidase Y.
- 3.3. The response of the isolated hindgut to the new peptide was distinguishable from the response to proctolin by the following features: (a) a longer interval following application (1–4 min) to reach a maximum contraction, and (b) a much larger amplitude for single phasic contractions. Like proctolin, the new peptide could cause a protracted stimulation of the hindgut for more than 2 hr.
15.
S E Banner S J Wood R H Osborne K J Cattell 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1990,95(2):233-236
1. Octopamine (OA) (10(-7)-10(-5) M) relaxed isolated foreguts. Tyramine mimicked the effects of OA but was 64x less potent. 2. Proctolin (10(-8) M to 10(-6) M) induced contraction of isolated foreguts was antagonised non competitively by tyramine. 3. Mianserin (10(-6) M) was a non competitive antagonist of relaxation caused by tyramine but was without effect on proctolin induced contraction. 4. Caffeine (1 microM and 2 microM) caused non competitive inhibition of proctolin-induced tissue contraction. 5. It is concluded that tyramine antagonises proctolin-induced contraction of the foregut by activating an adenylate cyclase-linked OA2 receptor. 相似文献
16.
Proctolin, a myotropic substance with potent activity on the proctodeal (hindgut) muscles of the cockroach, (L.), has been identified by the use of Edman degradation and dansylation techniques as Arg-Tyr-Leu-Pro-Thr. Synthesis of the pentapeptide having this sequence and exhibiting the properties of natural proctolin confirmed the structure. Threshold activity on proctodeal muscle occurs at about 10−9 M proctolin. 相似文献
17.
Modulatory effects of proctolin on a crab ventilatory muscle 总被引:1,自引:0,他引:1
Proctolin enhances nerve-evoked, phasic contractions of a selected respiratory muscle of the shore crab, Carcinus maenas, but has no effect on muscle tonus. Proctolin also increases the work and power output of this muscle. These effects are functionally appropriate in view of previous reports that proctolin stimulates the ventilatory rhythm. They also suggest that proctolin exerts coordinated modulatory control at the central and peripheral levels of the gill ventilatory system. In contrast, serotonin, dopamine and octopamine have no effect on this muscle. 相似文献
18.
James R. Groome Marianne de Tschaschell Winsor H. Watson III 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(5):631-643
1. The morphology and innervation of the midgut (intestine) in the horseshoe crab, Limulus polyphemus was investigated. The organization of this tissue was examined with routine histology. Radioimmunoassay, immunohistochemistry and high performance liquid chromatography were employed to detect, localize and identify peptidergic innervation of the midgut. The actions of synthetic and native proctolin-like and FMRFamide-like peptides were compared on the isolated midgut preparation. 2. Levels of proctolin and FMRFamide were determined in extracts of Limulus midgut tissue using radioimmunoassay. High levels of proctolin-like immunoreactivity (69.5 +/- 11.3 ng/g) were detected, while levels of FMRFamide-like immunoreactivity (0.8 +/- 0.2 ng/g) were less. Proctolin levels were equally distributed, while the levels of FMRFamide-like immunoreactivity exhibited an anterior bias. 3. Proctolin- and FMRFamide-like immunoreactivities in the Limulus midgut were localized with immunohistochemistry. Proctolin- and FMRFamide-immunoreactive elements were detected in intestinal nerve branches and individual fibers running along the surface of the midgut in whole-mount preparations. In sectioned tissue, staining for these peptides was observed throughout the midgut, typically associated with muscle bands and fibers. Only a few immunoreactive cell bodies were observed. 4. Proctolin, and several FMRFamide-like peptides produced distinct and opposing actions on the isolated Limulus midgut preparation. Proctolin elicited contracture and rhythmic contractions of this tissue, while FMRFamide and N-terminally extended analogs of FLRFamide relaxed gut tension. FMRFamide-like peptides partially reversed the excitatory actions of proctolin. 5. Proctolin- and FMRFamide-like peptides in Limulus midgut extracts were partially characterized with high performance liquid chromatography. One peak of proctolin-like activity was detected on a linear gradient of 18 to 31.5% acetonitrile. The native proctolin-like peptide produced excitatory actions on the isolated midgut preparation which were indistinguishable from those produced by synthetic proctolin. Several peaks of FMRFamide-like bioactivity (Busycon radula protractor muscle assay) were detected with a linear gradient of 5 to 30% acetonitrile. Fractions from two distinct peaks produced FMRFamide-like inhibitory effects on the isolated Limulus midgut preparation. These findings suggest a role for proctolin-like and FMRFamide-like peptides as regulators of intestinal motility in Limulus. 相似文献
19.
Neuromuscular transmission in an insect visceral muscle 总被引:2,自引:0,他引:2
The electrical properties of the muscles of locust oviduct have been examined using intracellular recordings. The muscle cells are both dye and electrically coupled. They possess a wide array of spontaneous electrical activity ranging from slow oscillations of membrane potential to action potentials. In addition to possessing spontaneous electrical activity, certain regions of the oviduct are under motor control. The amplitude of evoked excitatory junction potentials (EJPs) increased step wise revealing innervation from a maximum of three motor units. These EJPs underwent summation and facilitation, and reached a critical threshold at which point the membrane revealed an active response. Bath applied glutamate, aspartate, proctolin, and octopamine were tested for their ability to alter resting potential and EJPs. L-glutamate (1.6 X 10(-5) M and above) produced a dose-dependent depolarization of membrane potential accompanied by a reduction in amplitude of EJPs. Although L-aspartate resulted in similar effects, the concentrations required were higher than those for glutamate. Proctolin (6.3 X 10(-11) M-6.0 X 10(-9) M) resulted in a dose-dependent depolarization but had little or no effect on amplitude of EJPs. Application of D, L-octopamine (3.2 X 10(-5) M-1.7 X 10(-4) M) induced a small hyperpolarization and a reduction in amplitude of EJP. It is suggested that contractions of locust oviduct appear to be regulated by a combination of a classical neurotransmitter such as glutamate, along with the neuromodulators octopamine and proctolin. 相似文献
20.
Marciniak P Kuczer M Rosinski G 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(6):721-730
Three neuropeptides Zopat-MS-2 (pEDVDHVFLRFa), Zopat-SK-1 (pETSDDYGHLRFa) and Zopat-NVPL-4trunc. (GRWGGFA), recently isolated
from the neuroendocrine system of the Zophobas atratus beetle, were tested for their myotropic and hyperglycaemic activities in this species. These peptides exerted differentiated
dose-dependent and tissue specific physiological effects. Zopat-MS-2 inhibited contractions of the isolated heart, ejaculatory
duct, oviduct and hindgut of adult beetles and induced bimodal effects in the heart contractile activity of pupae in vivo.
It also increased the haemolymph free sugar level in larvae of this species, apart from myotropic activity. Zopat-SK-1 showed
myostimulatory action on the isolated hindgut of the adult beetles, but it decreased contractions of the heart, ejaculatory
duct and oviduct. Injections of this peptide at a dose of 2 μg also caused delayed cardioinhibitory effects on the heartbeat
of the pupae. Together with the ability to increase free sugar level in the haemolymph of larvae these were new physiological
activities of sulfakinins in insects. Zopat-NVPL-4trunc. inhibited the muscle contractions of the two organs: hindgut and
ejaculatory duct but it was inactive on the oviduct and the heart of the adult beetles. This peptide also increased free sugar
level concentration in the haemolymph of Z. atratus larvae. These physiological actions are the first biological activities discovered for this group of the insect peptides.
The present work showed pleiotropic activity of three neuropeptides and indicates that the visceral muscle contractions and
the haemolymph sugar homeostasis in Z. atratus are regulated by complex mechanisms. 相似文献