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At least 19 recordsLinked to original sources
PubMed1988

Optical monitoring of activity of many neurons in invertebrate ganglia during behaviors.

Optical methods for monitoring neuron activity were developed because these methods lend themselves to simultaneous multiple-site measurements. With the use of new voltage-sensitive dyes, the dye-related pharmacology and photodynamic damage appear to be relatively unimportant. Using multiple-site measurements made with a 124-element photodiode array, we estimated that approximately 30 of the 200 neurons present in the Navanax buccal ganglion make action potentials during feeding and that approximately 300 of the 1100 neurons present in the Aplysia abdominal ganglion are active during the gill-withdrawal reflex. The fact that a light mechanical touch to the siphon skin activated such a large number of neurons in the abdominal ganglion suggests that understanding the neuronal basis of the gill-withdrawal reflex and its behavioral plasticity may be forbiddingly difficult.

Animals↗
PubMed1989

Optical measurement of action potential activity in invertebrate ganglia.

Optical monitoring methods have reached the level of development where activity from a network of cells can be recorded in a minimally-dissected behaving animal. The spike activity in the buccal ganglion of Navanax was monitored during feeding and activity in the Aplysia abdominal ganglion was monitored during the gill-withdrawal reflex. Approximately 30 neurons in the Navanax buccal ganglion were active during feeding and between 250 and 400 neurons in the Aplysia abdominal ganglion were active during the gill-withdrawal reflex. A reasonably complete understanding of the neuronal basis of the gill withdrawal may not be possible with presently available scientific methods. Substantial improvements in signal-to-noise ratio in optical measurements will be necessary before the majority of synaptic potentials can be detected optically. Understanding circuits that involve more than a few neurons will be a challenge to neurobiologists.

Action Potentials↗
PubMed1993

Optical measurement of action potential activity in invertebrate ganglia.

With a voltage-sensitive dye and an array of silicon photodiodes we monitored the action potential activity of a large fraction of the cells in the Aplysia abdominal ganglion during the gill-withdrawal reflex. This capability allowed a direct determination of the spread of sensory information within the 1,000 neurons of the ganglion. Surprisingly, approximately 30% of the neurons are activated by a light touch to a small area of siphon skin. It is likely that many other neurons also receive large synaptic potentials, either excitatory or inhibitory, and thus even a very mild and restricted stimulus will have widely distributed effects. It seems to us that these results will force a more pessimistic view of the present understanding of the neuronal basis of apparently simple behaviors.

Action Potentials↗
PubMed1994

Microglia in invertebrate ganglia.

The results of this study lend strong support to the concept of the existence in insects and molluscs of a distinctive class of neuroglial cells comparable to vertebrate microglia. The evidence presented is as valid as that used in reference to the separate status of vertebrate microglia--i.e., the demonstration of a close structural and functional relationship of these cells with cells of the immune system. As in vertebrates, the excision of ganglia from three invertebrate species (the molluscs Planorbarius corneus and Mytilus edulis and the insect Leucophaea maderae) and their maintenance in incubation media led to an exodus of small cells and their accumulation in the culture dish. During this process, they underwent conformational changes from stellate to rounded, and then to more or less ameboid, comparable to those indicative of the process of activation in the animals' immunocytes. Functional characteristics which these translocated microglia-like cells share with immunocytes are motility, phagocytotic activity, and adherence to the culture dish. Furthermore, the two cells have certain biochemical features in common--e.g., the presence of certain cytokines and (at least in Planorbarius) that of corticotropin. An additional phenomenon of particular interest for the classification of microglial elements is their response to morphine. At 10(-6) M, this drug decreases not only the number of cells emerging from the excised ganglia but also the degree of their transformation to the "active" ameboid form. This dose-dependent and naloxone-sensitive effect of morphine on microglial cells parallels that on activated immunocytes of the same species. Corresponding results demonstrating an inhibitory effect of morphine on mobilized microglial cells of the frog Rana pipiens indicate that this relationship between the two cell types under consideration also exists in vertebrates. Binding and displacement experiments with membrane homogenates of microglial cells as well as immunocytes of Mytilus have shown that the effects of morphine on both cell types are mediated by the same special opiate receptor (mu 3).

Animals↗
PubMed2006

Alcohol-, nicotine-, and cocaine-evoked release of morphine from invertebrate ganglia: model system for screening drugs of abuse.

BACKGROUND: Invertebrates express regulatory receptors, transporters, and channels responsive to established drugs of abuse, many of which mediate their effects through catecholamine pathways. We hypothesized that invertebrate neural systems may serve as models by which to evaluate the interactive pharmacological effects of these agents. MATERIAL AND METHODS: Ex vivo pharmacological trials determined the effects of saturating levels of ethanol on morphine levels in pooled Mytilus edulis ganglia via HPLC coupled to electrochemical detection and/or HPLC/RIA analyses. Additional trials evaluated the ability of ethanol, nicotine, and cocaine, to promote evoked release of 125I-labeled morphine from neural tissues, because intrinsically low levels of morphine did not allow direct quantification of its release. RESULTS: Incubation of pooled M. edulis pedal ganglia with 200 mM ethanol (approximately 1% ethanol v/v) resulted in a two-fold increase in morphine concentration at 15 min, return to baseline at 30 min, and a 50% decrease in morphine concentration at 60 min. Separate incubations of pooled M. edulis pedal ganglia and H. americanus nerve cord with ethanol, cocaine, and nicotine resulted in a statistically significant enhancement of 125I-trace labeled morphine release. CONCLUSIONS: The stimulatory effects of ethanol, nicotine, and cocaine on cellular expression and release of endogenous morphine suggest convergent mechanisms underlying the reinforcing and addictive properties for a variety of drugs of abuse. The evolutionary conservation of L-tyrosine as a common precursor to catecholamine and opiate/opioid signaling systems may define a functional triad involving endogenous morphine, dopamine, and other classes of addictive drugs.

Animals↗
PubMed2004

Reticuline exposure to invertebrate ganglia increases endogenous morphine levels.

OBJECTIVES: Given the presence of morphine, its metabolites and precursors in mammalian and invertebrate tissues, it became important to determine if exposing tissues to an opiate alkaloid precursor, reticuline, would result in increasing endogenous morphine levels. METHOD: Endogenous morphine levels were determined by high pressure liquid chromatography coupled to electrochemical detection and radioimmunoassay following incubation of Mytilus edulis pedal ganglia with reticuline. Nitric oxide (NO) release was determined in real-time via an amperometric probe. Mu opiate receptor affinity for opiate alkaloid precursors was determined by a receptor displacement assay. RESULTS: Morphine is present in the pedal ganglia of Mytilus edulis (1.43 +/- 0.41 ng/mg +/- SEM ganglionic wet weight). Ganglia incubated with 50 ng of reticuline, a morphine precursor in plants, for 1 hour exhibited a statistical increase in their endogenous morphine levels (6.7 +/- 0.7 ng/mg tissue wet weight; P<0.01). This phenomenon is concentration dependent. The increase in ganglionic morphine levels occurs gradually over the 60 min incubation period, beginning 10 minutes post reticuline addition. We show that reticuline (10(-6) M) does not stimulate ganglionic NO release in a manner resembling that of morphine (10(-6) M), which releases NO seconds after its exposure to the ganglia and lasts for 5 minutes. With reticuline, there is a 3 minute delay, which is followed by an extended release period. Furthermore, in binding displacement experiments both reticuline and salutaridine (another morphine precursor) exhibit no binding affinity for the pedal ganglia mu opiate receptor subtype. This finding is further substantiated using the positive control of human monocytes where the mu3 opiate receptor subtype has been cloned. CONCLUSION: Taken together, we surmise that the morphine's precursors are being converted to morphine. The experiments strongly indicate that pedal ganglia can synthesize morphine from reticuline.

Alkaloids↗
PubMed2003

Spatial profiling invertebrate ganglia using MALDI MS.

The ability of MALDI TOF MS to spatially map peptides and proteins directly from a tissue is an exciting advance to imaging mass spectrometry. Recent advances in instrumentation for MS have resulted in instruments capable of achieving several micron spatial resolution while acquiring high-resolution mass spectra. Currently, the ability to obtain high quality mass spectrometric images depends on sample preparation protocols that often result in limited spatial resolution. A number of sample preparation and matrix deposition protocols are evaluated for spatial profiling of Aplysia californica exocrine gland and neuronal tissues. Such samples are different from mammalian tissues, but make good targets for method optimization because of the wealth of biochemical information available on neuropeptide processing and distribution. Electrospray matrix deposition and a variety of freezing methods have been found to be optimum for these invertebrate tissues, with the exact protocols being tissue dependent.

Animals↗
PubMed2002

Cyclic nitric oxide release by human granulocytes, and invertebrate ganglia and immunocytes: nano-technological enhancement of amperometric nitric oxide determination.

BACKGROUND: Various tissues from vertebrates and invertebrates respond to external signal molecules by rapid release of nitric oxide (NO) mediated by constitutive nitric oxide synthase. MATERIAL/METHODS: Invertebrate immunocytes were collected from maintained stock and human granulocytes were isolated from leukocyte-enriched blood obtained from the Long Island Blood Services. The invertebrate ganglionic tissue was either extracted or exposed for ex vivo and in vivo evaluation. Nitric oxide release was measured using a newly developed NO-selective nanoprobe, exhibiting enhanced sensitivity. RESULTS: Evaluation of NO release from the pedal ganglia of the marine bivalve, Mytilus edulis, demonstrated in vitro release of NO that fluctuated from 969 to 1003 pM, with a mean change in NO of 35 pM/cycle and a mean cycle time of approximately 4 minutes. Basal release of NO/cycle from the ganglia in vivo was increased significantly to approximately 65 pM (P<0.05) with an increase in cycle time to approximately 7 minutes. Exposure of the ganglia to morphine in vivo resulted in a significant increase in NO release and a lack of NO pulsations. The fluctuation in NO release from immunocytes of Mytilus edulis was approximately 27 pM per cycle with a cycle time of 4 minutes whereas human granulocytes release fluctuated approximately 23 pM with a cycle time of 6 minutes. CONCLUSIONS: These data demonstrate that basal release of NO from various tissues is released in a cyclic manner and the cycle time and magnitude is subject to regulation by external stimuli.

Animals↗
PubMed1984

Alterations in high-affinity binding characteristics and levels of opioids in invertebrate ganglia during aging: evidence for an opioid compensatory mechanism.

In Mytilus and Leucophaea the high-affinity binding site density is significantly lower in old animals than in young animals, whereas the low-affinity site density remains unchanged. In Mytilus the estimated met-enkephalin and met-enkephalin-Arg6-Phe7 levels are significantly higher in old than in young animals. In Leucophaea only the met-enkephalin level can be determined, and it is also higher in old animals. The decrease in the high-affinity binding site density and the corresponding increase in endogenous enkephalin levels suggest the existence of an opioid compensatory mechanism associated with the aging process. In Mytilus there is a demonstrated decrease with age in intraganglionic dopamine levels in response to applied opiates. In addition, the inhibition of dopamine-stimulated adenylate cyclase activity by opiates also decreases in older animals. In Leucophaea the sex difference in opioid binding densities diminishes with age.

Adenylyl Cyclases↗
PubMed1992

Glial localization of interleukin-1 alpha in invertebrate ganglia.

1. Mytilus pedal ganglion contains a small population of glial cells that are immunopositive for interleukin-1 alpha. Positively stained fibers can also be seen in the neuropil of these sections. 2. The marine worm Nereis diversicolor also exhibits positive neural immunostaining for interleukin-1 alpha. 3. Both organisms contain hemocytes that contain immunoactivity for interleukin-1 alpha. The study suggests interleukin-1 alpha to be an ancient cytokine given its presence in organisms that evolved significantly earlier than mammals.

Animals↗
PubMed1981

High resolution analysis of [3H]2-deoxyglucose incorporation into neurons and glial cells in invertebrate ganglia: histological processing of nervous tissue for selective marking of glycogen.

The 2-deoxyglucose (2-DG) autoradiographic technique, in conjunction with 3H-labelled 2-DG and glutaraldehyde fixation, was applied to the isolated ganglia of the leech and the snail in order to analyse its potential use for the understanding of energy utilization in these simple nervous systems. Approximately 50% of the label is retained in these tissues after histological processing, and the method can be satisfactorily applied at the subcellular level. In both species most neurons progressively accumulate radioactivity over 15 min-1 h, although to different extents. In the leech the glial cells showed greater uptake than the neurons. Paired homologous neurons in contralateral buccal ganglia of the snail were equally labelled. In all structures studied by electron-microscope autoradiography the label was positively associated with glycogen. Freshly extracted glycogen from ganglia previously exposed to 2-DG was significantly labelled (2-10% of total radioactivity in the ganglia); thus the glutaraldehyde fixation did not appear responsible for artifactual binding of the label. The significance of the glycogen labelling and the potential of the technique for metabolic mapping in these nervous systems are discussed.

Animals↗
PubMed1986

Simultaneous monitoring of activity of many neurons from invertebrate ganglia using a multielement detecting system.

The optical monitoring system has reached a level of sophistication where activity from a network of cells can be recorded in a minimally dissected behaving animal. We monitored activity in the buccal ganglion of the mollusk, Navanax inermis, during spontaneous expansions and during feeding. Deleterious pharmacological effects and photodynamic damage appear to be negligible in this preparation. The S/N is large enough to detect individual cell's activity without signal averaging, provided the cell soma is of sufficient size (greater than 20 microns). Indeed, if the S/N is large enough, it is possible to see graded or subthreshold potentials without the use of signal averaging. The activity of adjacent cells in the same focal plane could be detected as different cells by a single detector. In addition, cells that were out of focus but whose projected images fell on a detector also have their activity recorded as a significant signal by that detector. This finding suggested that recording from all the cells in a ganglion was possible. Preliminary evidence suggests that our recordings from Navanax buccal ganglia are at least 70% complete. It appears that the assumption that most of the cells' activity is being recorded is reasonable. A problem that could prevent correct identification of activity was the effect of light scattering on the signal. A signal dispersed owing to light scattering could give an erroneous estimate as to the cell size. However, the effect of light scattering on Navanax signals is small, and we feel that our estimates of cell size are accurate.

Animals↗
PubMed2003

Endogenous pacemaker potentials develop into paroxysmal depolarization shifts (PDSs) with application of an epileptogenic drug.

Well-known invertebrate ganglia (buccal ganglia of Helix pomatia, abdominal ganglia of Aplysia californica) were used to study the contribution of synaptic potentials, central pattern generators, and endogenously generated neuronal potentials to the development of epileptiform activity. Epileptiform activity which was induced with application of pentylenetetrazol (1 to 100 mM) or etomidate (0.12 to 1.0 mM) consisted of paroxysmal depolarization shifts (PDSs) recorded simultaneously from several identified neurons with sharp microelectrodes. With application of an epileptogenic drug, endogenous pacemaker potentials develop into PDSs. With increasing concentration of the drug, (i) amplitude of pacemaker-depolarizations and (ii) delay of pacemaker-repolarization increased progressively finally resulting in PDSs. Additionally, the activation characterists of currents shifted from between -50 and -40 mV (pacemaker potentials, control conditions) to between -100 and -40 mV (PDS, epileptic conditions). Only neurons which generated pacemaker potentials under control conditions could generate PDSs under epileptic conditions. Chemical synaptic inputs triggered or blocked pacemaker potentials as well as PDSs. Activities induced from central pattern generators were identified with simultaneous recordings from several identified neurons. The central pattern generators could trigger or block pacemaker potentials as well as PDSs. Results demonstrate that, in the used model nervous systems, pacemaker potentials which are generated by the single neurons are the physiologic basis of epileptic activity.

Animals↗
PubMed2006

Alcohol-, nicotine-, and cocaine-evoked release of morphine from human white blood cells: substances of abuse actions converge on endogenous morphine release.

BACKGROUND: Normal human white blood cells (WBC) have the ability to synthesize morphine as do invertebrate ganglia. Furthermore, invertebrate neural tissues incubated with ethanol, cocaine, or nicotine results in a statistically significant enhancement of labeled morphine release. We now demonstrate that this also occurs with human WBC. MATERIAL/METHODS: Human blood was obtained from the Long Island Blood Services (Melville, NY). Polymorphonuclear cells (PMN) or mononuclear cells (MN) (10 million/ml) were bathed in phosphate buffered saline (PBS) medium containing purified RIA grade 125I-labeled morphine for trace labeling and quantification of media concentrations of morphine were via RIA. Cells were then incubated with cocaine, alcohol or nicotine and morphine release was determined. Residual levels of radioactivity in control tissues were always greater than 65% of total cpm, whereas in treated tissue differences depended on the amount of drug added. RESULTS: Incorporation rates of 125I-labeled morphine into PMN and MN were 7.85+/-0.36% and 1.42+/-0.19%, respectively. Separate incubations of PMN with ethanol, cocaine, or nicotine resulted in a statistically significant enhancement of 125I-labeled morphine released into the extracellular medium in a concentration dependent manner. CONCLUSIONS: These substances of abuse have been linked into a common pathway because of the common dopamine connection. Now, they are additionally linked because of their common effect on endogenous morphinergic processes. It is highly significant that these substances of abuse converge on a similar process, providing a mechanism to initiate their pleasure and addicting actions with continued frequent use.

Alcohols↗