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At least 1,063 records · Page 59Linked to original sources

PubMed1983

Behavior of intracellular cyclic nucleotide and calcium in pentylenetetrazole-induced bursting activity in snail neurons.

To elucidate the intracellular mechanism of the bursting activity which is characteristic of seizure discharge, the behavior of the intracellular cyclic nucleotide and the intracellular calcium during pentylenetetrazole (PTZ)-induced bursting activity in snail neurons was investigated. Cyclic AMP was increased about 3-fold by the incubation of ganglia with PTZ. The effect of PTZ on phosphodiesterase activity measured using either cyclic AMP or cyclic GMP as substrate showed a slight increase in cyclic AMP phosphodiesterase activity. The release of calcium from the lysosome fraction was increased by the incubation of ganglia with dibutyryl cyclic AMP. Protein kinase activity was stimulated by the incubation of ganglia with PTZ. Adenylate cyclase activity was stimulated by the incubation of ganglia with PTZ. These findings suggest that PTZ-induced bursting activity in snail neurons is initiated by an intracellular increase of cyclic AMP, which promotes calcium release from lysosomes and induces protein kinase activation.

Adenylyl Cyclases↗

PubMed1987

Intracellular calcium concentration during pentylenetetrazol-induced bursting activity in snail neurons.

To clarify the role of intracellular free calcium in the provocation of bursting activity, the intracellular calcium concentration was measured using calcium-sensitive microelectrodes during pentylenetetrazol (PTZ)-induced bursting activity in snail neurons. In the PTZ-sensitive neurons of the snail, Euhadra peliomphala, the intracellular calcium concentration was higher than that in the normal state during PTZ-induced bursting activity, but lower than that which induced the calcium-activated potassium conductance elevation. By application of 50 microM calcium ionophore, A23187, a slight increase in intracellular calcium concentration with a slight depolarization occurred. Then a greater increase of intracellular calcium concentration with bursting activity was observed. By application of 100 microM A23187, a rapid and intense increase of intracellular calcium concentration with hyperpolarization was observed. These findings suggest that, for the provocation of bursting activity, sustained elevation of the intracellular calcium concentration, higher than that in the normal state but lower than that which evokes calcium-activated potassium conductance elevation, is required.

Action Potentials↗

PubMed1993

Repeated naloxone treatments and exposures to weak 60-Hz magnetic fields have 'analgesic' effects in snails.

Results of studies with rodents have shown that animals repeatedly injected with the opioid antagonist, naloxone, acquire a hypoalgesic response to thermal nociceptive stimuli. The present study revealed a similar response in the terrestrial pulmonate snail, Cepaea nemoralis. Snails receiving daily injections of naloxone followed by measurements of thermal nociceptive sensitivity also developed hypoalgesia. Daily brief (30-min) exposures to a weak 60-Hz magnetic field (1.0 gauss or 0.1 mT), which acutely antagonize opioid-mediated nociception and antinociception in a manner comparable to that of naloxone, also led to the expression of a hypoalgesic responses. This suggests that opioid antagonist-induced thermal hypoalgesia may be a basic feature of opioid systems. This naloxone- and magnetic field-induced 'analgesia' is consistent with either a facilitation of aversive thermal conditioning and or antagonism of the excitatory, hyperalgesic effects of low levels of endogenous opioids.

Analgesia↗

PubMed1985

[Control of secretory activity of multifid glands by castration and grafting in the snail Helix aspersa].

Castration of juvenile snails results in a cessation of multified gland cell differentiation. Many months later, the cells still resemble polarized epithelial cells and show no signs of secretory activity. Transplantation of nondifferentiated cells from multifid gland of castrated snails into normal adults initiated secretory activity. The experiments show that the presence of the gonad is essential for the multifid glands to develop secretory activity and that its influence is mediated by an endocrine factor which is transported in the hemolymph.

Animals↗

PubMed1989

Variations of somatostatin-like immunoreactivity in the circumoesophageal ganglia, the hepatopancreas, the mantle edge, and the hemolymph of shell-repairing snails (Helix aspersa).

Immunocytology and radioimmunoassays demonstrate the presence of immunoreactive somatostatin-like (IR-SOM-LI) material in the tissues of young or adult snails Helix aspersa bred under short or long day in controlled artificial conditions. Neurosecretory cells in the circumoesophageal ganglia and in the digestive gland, small fibers in the hepatopancreas, and small granules in the mantle epithelial cells are immunoreactive toward antisomatostatin. In all experimented animals shell fractures induce variations of the IR-SOM-LI concentrations in all assayed tissues whatever the lighting conditions were underwent. These findings support the hypothesis that in Helix one or more substances related to the vertebrate tetradecapeptide is (are) involved in the repair processes but that the storage and the metabolism may be different during the biological cycle of the snails. These results are compared with those previously published using different gastropods and different methods.

Animals↗

PubMed1992

Enzyme studies on human and snail beta-mannosidase using a fluorescence assay and an HPLC/diode array method with Man beta (1-4)GlcNAc as substrate.

1. Snail beta-mannosidase showed a Km value of 0.05 mM toward MU-beta-Man and could not be inhibited by Man, GlcNAc, Man beta(1-4)GlcNAc, Man beta(1-4)GlcNAc beta(1-N)urea or Man beta(1-4) GlcNAc beta(1-4)GlcNAc. 2. The Km value of the snail enzyme towards Man beta(1-4)GlcNAc, as measured by HPLC, was 10 mM, explaining the lack of inhibition. 3. The Km value of the human serum beta-mannosidase towards MU-beta-Man was 0.3 mM, but the human enzyme was not capable of degrading Man beta(1-4)GlcNAc in detectable amounts.

Animals↗

PubMed1994

Anticardiolipin antisera from lupus patients with seizures reduce a GABA receptor-mediated chloride current in snail neurons.

The effects of circulating anticardiolipin (ACL) antisera in lupus patients on the LP5 central neuron of snail were studied. Both GABA and glutamate increased a chloride conductance of the LP5 neuron. The ACL antisera decreased the GABA-elicited responses in a concentration dependent manner while it had no effect on glutamate-elicited responses. The ACL antisera affected neither the resting membrane current, nor the membrane conductivity of neuron. Antisera without the activity of anticardiolipin did not decrease the GABA-elicited responses. The seizure incidence of the patients with higher ACL antisera levels is also higher. It is concluded that ACL antisera inhibited the GABA ionophore receptor complex in a snail central neuron.

Animals↗

PubMed1976

Use of snail enzyme for the selection of glucose-and mannose-negative mutants in Saccharomyces cerevisiae.

The relationship between growth and sensitivity of Saccharomyces cerevisiae cells to snail enzyme led us to work out the conditions for using this enzyme to isolate mannose-negative and glucose-negative mutants. The technique is based on a prior growth on a glycerol medium in which any cell becomes resistant to snail enzyme, followed by a period of growth in a medium in which only the wild-type cells can grow, thereby becoming sensitive to the enzyme. This technique was very effective in both tested cases. This result suggests that the method described might also be applied to isolate other kinds of mutant.

Ethyl Methanesulfonate↗

PubMed1993

Acetylcholine receptor binding characteristics of snake and cone snail venom postsynaptic neurotoxins: further studies with a non-radioactive assay.

The binding of postsynaptic neurotoxins from snake and marine cone snail (Conus sp.) venoms to nicotinic acetylcholine receptor (AchR) was investigated with an ELISA-based, non-radioactive assay. Three snake postsynaptic toxins from the long-chain group (Naja naja kaouthia cobratoxin, Naja oxiana neurotoxin I, Bungarus multicinctus alpha-bungarotoxin) and short-chain group (Naja naja atra cobrotoxin, Naja oxiana neurotoxin II, and Laticauda semifasciata erabutoxin b) were studied. Both types of snake postsynaptic toxins showed a dose-response with constant AchR (50 micrograms/ml) and varying toxin concentrations (50-0.035 micrograms/ml). The minimum detection limits of the assay for snake toxins ranged from 310 to 1240 ng/ml (40-160 pmole/ml), depending on the toxin. Unlike any of the short-chain toxins, long-chain toxins consistently bound less receptor and reached maximum absorbance levels with toxin concentrations of 10-50 micrograms/ml. Competition for AchR binding between cone snail postsynaptic neurotoxins (conotoxins GI, MI, SI) and alpha-bungarotoxin or cobrotoxin resulted in a dose-response. The postsynaptic conotoxins were uniformly better competitors for AchR binding with alpha-bungarotoxin than with cobrotoxin. Heat stability studies with neurotoxin I, erabutoxin b, or cobrotoxin revealed a loss in AchR binding activity with increasing temperature. alpha-Bungarotoxin heated at 90 degrees C had increased AchR binding activity by 105%, relative to 25 degrees C samples, but lost the majority of its binding activity after 100 degrees C. The enhanced binding of heated alpha-bungarotoxin to AchR was specific, as evidenced by a competitive dose-response with unheated alpha-bungarotoxin, but heated toxin lacked any biological activity in the mouse lethal assay. When conotoxins GI or MI were heated at 100 degrees C, there was no detectable loss in AchR binding activity, and only a slight decrease in mouse lethality.

Animals↗

PubMed1995

Bioaccumulation and toxic effects of elevated levels of 3,3',4,4'-tetrachloroazobenzene (33'44'-TCAB) towards aquatic organisms. III: Bioaccumulation and toxic effects of detrital 33'44'-TCAB on the aquatic snail, Indohiramakigai (Indoplanorbis exustus).

The polychlorinated aromatic compound 3,3',4,4'-tetrachloroazobenzene (33'44'-TCAB) is a contaminant of many 3,4-dichloroaniline (3,4-DCA) based herbicides, and of agricultural soils. In this study, the aquatic snail Indohiramakigai (Indoplanorbis exustus) was exposed to detrital 33'44'-TCAB. The snails absorbed 33'44'-TCAB from their environment, but only to a maximum level of approximately 287 ppb (whole body basis). This level of 33'44'-TCAB did not appear to cause any harmful effects.

Animals↗

PubMed1983

Non-respiratory haemolymph proteins in the vineyard snail Helix pomatia. Changes after phagocytosis in vivo.

Haemolymph proteins from the vineyard snail Helix pomatia were studied by chromatographic and immune-electrophoretic techniques with the dual purpose of characterizing the normal composition of haemolymph and to look for possible opsonins. The oxygen-carrying proteins, alpha- and beta-haemocyanin, were by far the most abundant proteins, but at least three non-respiratory proteins could be demonstrated. We found consistent changes in the appearance of the immunoprecipitation pattern of these non-respiratory proteins after the injection of particulate foreign matter into the snail's circulation, and we suggest that they may be opsonins. We also found a haemagglutinin in haemolymph. It was present in very low concentration and was similar to, but not identical with the haemagglutinin which is present in the albumin gland.

Animals↗

PubMed1984

A precipitin for human serum proteins as released under stress by a marine invertebrate, the marsh snail, Littorina irrorata.

A substance released into the environment by stressed marsh snails, Littorina irrorata, precipitates with the beta globulin and albumin fractions of human serum proteins. Other diverse invertebrate species may produce a similar substance. Invertebrate precipitins have not been widely reported, and none like the one described. Some physicochemical and adaptive characteristics of the snail precipitin are presented. This precipitin can be produced in large quantities and has potential application as a diagnostic reagent.

Animals↗

PubMed1983

Detection of snail hemocyanin in the whole hemolymph by serologically specific electron microscopy.

This study demonstrates the applicability of the serologically specific electron microscopy (SSEM) technique in the detection of hemocyanin molecules in the whole hemolymph of the snail, Megalobulimulus ovatus. The results are positive and easily reproducible. The SSEM might be useful as a technique for taxonomic studies of snails as well as to study structural aspects of their hemocyanin molecules.

Animals↗

PubMedDate not supplied

MIF-1 and Tyr-MIF-1 antagonize morphine and opioid but not non-opioid stress-induced analgesia in the snail, Cepaea nemoralis.

The effects of prolyl-leucyl-glycinamide (MIF-1, PLG), tyrosine-prolyl-leucyl-glycinamide (Tyr-MIF-1, YPLG) and naloxone on morphine and warm and cold stress-induced increases in the latency of the thermal (40 degrees C hot plate) avoidance behaviors of the terrestrial snail, Cepaea nemoralis, were examined. All three substances blocked the morphine- and warm stress-induced opioid analgesia, while having no effects on non-opioid cold stress-induced analgesia. Tyr-MIF-1 had a significantly greater inhibitory effect than MIF-1. These results indicate that MIF-1 and Tyr-MIF-1 antagonize the antinociceptive effects of exogenous opiates and opioid-mediated analgesia in snails in a manner analogous to that described for mammals. This raises the possibility of an evolutionary conservation of functional opioid antagonists.

Animals↗

PubMedDate not supplied

Pertussis toxin reduces the day-night rhythm of nociception and mu and kappa opioid peptide-mediated antinociception in the snail, Cepaea nemoralis.

There is accumulating evidence that pertussis toxin-sensitive G proteins are associated with the transduction of opioid-mediated antinociception in mammals. The present study examined the effects of hemocel injections of pertussis toxin (0.10 microgram) on the day-night rhythm of nociception and mu and kappa opioid-mediated antinociception in a mollusc, the land snail, Cepaea nemoralis. Five days after treatment, pertussis toxin significantly reduced the naloxone-sensitive, opioid-mediated nocturnal peak in the day-night rhythm of nociception [as measured by the latency of response to a thermal (40 degrees C) stimulus] in Cepaea, without affecting the daytime response latency. Pertussis toxin also significantly decreased the antinociceptive effects of the mu agonist, DAMGO, and blocked those of the kappa opioid agonist, U-69,593. These results suggest that G protein substrates of pertussis toxin are associated with the transduction of opioid-mediated nociception and antinociception in the snail, Cepaea.

Animals↗

PubMedDate not supplied

Antinociceptive effects of the enkephalinase inhibitor, SCH 34826, in the snail, Cepaea nemoralis.

In vertebrates the effects of endogenous opioid peptides are limited by proteolytic enzymes such as endopeptidase 24.11 (enkephalinase), which cleaves the Gly-Phe bonds in both methionine- and leucine-enkephalin. SCH 34826 ((S)-N-[n-[1-[(2,2-dimethyl-1,3-dioxolan-4yl) methoxy]carbonyl]-2-phenylethyl]-L-phenylalanine-B-alanine) is a potent, highly specific, enkephalinase inhibitor that has marked analgesic effects in mammals. The present study examined the effects of SCH 34826 on opioid-mediated aversive thermal (nociceptive) response of an invertebrate, the land snail, Cepaea nemoralis. SCH 34828 had significant, dose-related antinociceptive effects in Cepaea that were reduced by naloxone and completely blocked by the specific data opiate antagonist, ICI-174,864, and only weakly affected by the specific kappa opiate antagonist nor-binaltrophimine. These findings with SCH 34826 suggest that an enkephalinase similar to that in vertebrates is present and involved in the mediation of opioid (enkephalin) activity in the snail, Cepaea.

Analgesics↗

PubMed1996

Pronociceptive effects of the neuropeptide, nociceptin, in the land snail, Cepaea nemoralis.

The peptide, Phe-Gly Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln-OH, recently isolated from rat brain, has been suggested to be an endogenous agonist for an orphan, opioid-like receptor (ORL1). This peptide, called "nociceptin" (or orphanin FQ), has been suggested to have pronociceptive, hyperalgesic functions. The present study examined the effects of nociceptin on aversive thermal (nociceptive) responses in an invertebrate, the land snail, Cepaea nemoralis. Nociceptin had significant, dose-related pro-nociceptive effects in Cepaea, whereas the opioid peptide, dynorphin A, which shares some sequence similarities with nociceptin, had significant antinociceptive effects. The effects of dynorphin were blocked by the kappa-opiate receptor antagonist, nor-binaltorphimine, whereas those of nociceptin were unaffected. Repeated daily administrations of nociceptin resulted in reduced pronociceptive effects, suggestive of the development of tolerance to the hyperalgesic actions of this opioid-related peptide. These findings suggest that the novel peptide, nociceptin, can influence nociceptive responses in the snail, Cepaea, in a manner similar to that indicated for rodents.

Amino Acid Sequence↗

PubMed1993

Effects of the small cardioactive peptide B (SCPB) on adenylate cyclase of the central nervous system and peripheral organs of the freshwater snail Planorbarius corneus.

The effect of the small cardioactive peptide B (SCPB) on adenylate cyclase activity of the central nervous system (CNS) and some peripheral organs of the freshwater snail Planorbarius corneus was investigated. This peptide stimulates enzyme activity in a dose-dependent manner in all the tested ganglia, in the salivary glands, the buccal mass and the oesophagus. The amount required for half-maximal stimulation is approx 0.1 microM. Moreover, the response of adenylate cyclase to SCPB progressively increases with time, without desensitizing. On the other hand, the peptide is ineffective on heart adenylate cyclase. The responsiveness of adenylate cyclase activity to the peptide and the wide distribution of SCPB-related immunoreactivity in all the tested ganglia suggest that this substance may exert an important role as neurotransmitter as well as neuromodulator in the CNS of the snail. Since SCPB is consistently present in the buccal and cerebral ganglia, associated nerves, salivary glands, buccal mass and oesophagus, and in the light of the appreciable effects exerted by SCPB on adenylate cyclase activity in the examined peripheral tissues, we suggest that the peptide is strongly involved in the control of feeding behaviour of P. corneus.

Adenylyl Cyclases↗