scholarly journals A GABAB receptor on an identified insect motor neurone

1995 ◽  
Vol 198 (4) ◽  
pp. 889-894
Author(s):  
D Bai ◽  
D Sattelle
Keyword(s):  
Cell Body ◽  
Periplaneta Americana ◽  
Gabab Receptor ◽  
Reversal Potential ◽  
Motor Neurone ◽  
Induced Responses ◽  
K Channels ◽  
Metathoracic Ganglion

The vertebrate GABAB receptor (GABABR) agonists 3-aminopropylphosphonous acid (3-APPA), SK&F97541 and 3-aminopropylphosphonic acid (3-APA) are able to induce a hyperpolarization on the cell body of motor neurone Df in the metathoracic ganglion of the cockroach (Periplaneta americana), although the classic vertebrate GABABR agonist l-baclofen fails to induce any responses on the same neurone. Consistent with the findings on vertebrate GABABRs, the 3-APPA-induced responses on Df were also insensitive to the GABAAR antagonists bicuculline and picrotoxin. However, the GABABR antagonists saclofen and CGP35348 also failed to block this GABAB-like response. These results indicate a novel pharmacology for the GABAB-like receptors on the Df neurone. The reversal potential indicates that these GABAB-like receptors may be coupled to K+ channels.

Pharmacology of skeletal muscle GABA-gated chloride channels in the cockroach Periplaneta americana.

1997 ◽  
Vol 200 (23) ◽  
pp. 2947-2955
Author(s):  
M Schnee ◽  
J Rauh ◽  
S D Buckingham ◽  
D B Sattelle
Keyword(s):  
Skeletal Muscle ◽  
Cell Body ◽  
Gaba Receptors ◽  
Gaba Receptor ◽  
Chloride Channels ◽  
Periplaneta Americana ◽  
Motor Neurone ◽  
Aminobutyric Acid ◽  
Induced Responses ◽  
Muscle Responses

The pharmacology of -aminobutyric acid (GABA)-gated chloride channels of the coxal levator (182c,d) muscle of the cockroach Periplaneta americana has been investigated and the data compared with similar findings for the cell body of the cockroach fast coxal depressor motor neurone (Df). Muscle GABA receptors resembled those of the motor neurone cell body in their sensitivity to picrotoxinin and insensitivity to bicuculline. However, muscle GABA receptors were insensitive to the neuronal GABA receptor agonists isoguvacine (10(-4) mol l-1) and 3-aminopropane sulphonic acid (10(-3 )mol l-1). The benzodiazepine flunitrazepam, which at 10(-6 )mol l-1 greatly enhances the amplitude of the motor neurone GABA-induced responses, failed to affect muscle responses to GABA when tested at the same and at a higher (10(-4 )mol l-1) concentration. The convulsant t-butylbicyclophosphorothionate was a weak antagonist of cockroach muscle GABA receptors, whereas several cyclodienes were much more effective antagonists. Thus, studies using a benzodiazepine and several convulsant antagonists reveal differences in the pharmacology of muscle and neuronal GABA receptors of the cockroach Periplaneta americana.

Structure and Synaptic Activation of the Fast Coxal Depressor Motoneurone of the Cockroach, Periplaneta Americana

1972 ◽  
Vol 56 (3) ◽  
pp. 647-656
Author(s):  
J. F. ILES
Keyword(s):  
Cell Body ◽  
Periplaneta Americana ◽  
Excitatory Input ◽  
Synaptic Activation ◽  
Synaptic Response ◽  
Metathoracic Ganglion ◽  
Procion Yellow ◽  
Giant Fibres

1. Using Procion Yellow dye injection the structure of the fast coxal depressor motoneurone was determined. 2. The cell body of the slow depressor motoneurone was located within the metathoracic ganglion. 3. Intracellular records from the fast motoneurone failed to reveal any post-synaptic response when the largest abdominal giant fibres were stimulated. 4. Smaller abdominal afferent fibres gave an excitatory input.

scholarly journals L-Glutamate Receptors on the Cell Body Membrane of an Identified Insect Motor Neurone

1989 ◽  
Vol 144 (1) ◽  
pp. 449-462 ◽  
Author(s):  
K. A. WAFFORD ◽  
D. B. SATTELLE
Keyword(s):  
Glutamate Receptors ◽  
Cell Body ◽  
Time Course ◽  
Periplaneta Americana ◽  
Chloride Concentration ◽  
Motor Neurone ◽  
Diethyl Ester ◽  
Equilibrium Potential ◽  
Receptor Subtypes ◽  
Similar Time

Current-clamp experiments on an identified neurone have demonstrated the presence of L-glutamate receptors in the insect central nervous system. The cell body of the fast coxal depressor motor neurone (Df) in the metathoracic ganglion of the cockroach Periplaneta americana exhibits a hyperpolarizing response to L-glutamate, accompanied by an increase in membrane conductance. The response is dependent on both intracellular and extracellular chloride concentration, but is not affected by changes in potassium concentration. The hyperpolarization reverses at −82mV (the equilibrium potential for chloride), is mimicked by the action of L-aspartate, blocked by the antagonists picrotoxin and γ-D-glutamylglycine (γ-DGG) at high concentrations (1.0×10−4mol l−1), and is enhanced by L-amino phosphonobutyrate (L-APB). The response is insensitive to glutamate diethyl ester (GDEE), cis-2,3-piperazine dicarboxylic acid (cis-2,3- PDA) and D-amino phosphonobutyrate (D-APB). The 1-glutamate-activated increase in chloride conductance does not cross-desensitize with the γ-aminobutyric acid (GAB A) response on the same cell. It is less sensitive than the GAB Aresponse to block by picrotoxin. In addition, γ-DGG specifically blocks the L-glutamate receptor. A depolarizing response is elicited by kainate and quisqualate; it is associated with an increase in conductance, and exhibits a much slower time course than the response to 1-glutamate, indicating a different underlying mechanism. L-Cysteate produces a small depolarizing response of similar time course to that produced by 1-glutamate. L-Homocysteate and N-methyl-D-aspartate (NMDA) are ineffective on the cell body membrane when applied at concentrations up to 1.0×10−3mol l−1. This first detailed description of the properties of L-glutamate receptors on an identified insect neurone reveals that they are not readily accommodated in the existing classification of receptor subtypes, based on vertebrate pharmacology.

The Physiology and Morphology of Median Nerve Motor Neurones in the Thoracic Ganglia of the Locust

1982 ◽  
Vol 96 (1) ◽  
pp. 325-341
Author(s):  
MALCOLM BURROWS
Keyword(s):  
Synaptic Input ◽  
Motor Neurone ◽  
Abdominal Muscles ◽  
Thoracic Ganglia ◽  
Synaptic Potentials ◽  
Metathoracic Ganglion ◽  
Inspiratory Motor ◽  
Motor Neurones ◽  
Chemical Synapses ◽  
The Right

Simultaneous intracellular recordings have been made from the two expiratory, and from the two inspiratory motor neurones which have their axons in the unpaired median nerves of the thoracic ganglia. Each motor neurone has an axon that branches to innervate muscles on the left and on the right side of one segment. The expiratory neurones studied were those in the meso- and meta-thoracic ganglia which innervate spiracular closer muscles. The depolarizing synaptic potentials underlying the spikes during expiration are common to the two closer motor neurones in a particular segment. Similarly, during inspiration when there are usually no spikes, the hyperpolarizing, inhibitory potentials are also common to both motor neurones. The synaptic input to the neurones can be derived from four interneurones; two responsible for the depolarizing potentials during expiration and two for the inhibitory potentials during inspiration. The inspiratory neurones studied were those in the abdominal ganglia fused to the metathoracic ganglion which innervate dorso-ventral abdominal muscles. During inspiration the two motor neurones of one segment spike at a similar and steady frequency. The underlying synaptic input to the two is common. During expiration, when there are usually no spikes, the hyperpolarizing synaptic potentials are also common to both neurones. In addition they match exactly the depolarizing potentials occurring at the same time in the closer motor neurones. The same set of interneurones could be responsible. No evidence has been revealed to indicate that the two closer, or the two inspiratory motor neurones of one segment are directly coupled by electrical or chemical synapses. The morphology of both types of motor neurone is distinct from that of other motor neurones in these ganglia. Both types branch extensively in both the left and in the right areas of the neuropile.

Electrical Characteristics of the Membrane Of An Identified Insect Motor Neurone

1980 ◽  
Vol 86 (1) ◽  
pp. 49-61
Author(s):  
G. F. GWILLIAM ◽  
M. BURROWS
Keyword(s):  
Electrical Properties ◽  
Conduction Velocity ◽  
Average Velocity ◽  
Motor Neurone ◽  
Electrical Characteristics ◽  
Initiation Zone ◽  
Active Membrane ◽  
Metathoracic Ganglion ◽  
Different Parts

1. The electrical properties of the membrane of an identified locust motor neurone, the fast extensor tibiae in the metathoracic ganglion, have been investigated to determine: the distribution of excitable and inexcitable membrane; the impulse initiation zone; and the conduction velocity of the spike in the ganglion and in the axon. 2. The waveform of extracellularly recorded spikes indicates that the transition from inactive to active membrane occurs along the region of the neurite which bears many arborizations within the neuropile. 3. Measurements of the delay between orthodromically or antidromically evoked spikes, recorded at the soma and other points along the neurite, place the impulse initiating zone close to the transition between active and inactive membrane. 4. Within the ganglion, the spike is conducted at different velocities over different parts of the neurite. The average velocity within the ganglion is, however, only about a seventh of that in the axon (0.54 m.s−1 against 4.1 m.s−1).

scholarly journals Ionic Basis of Membrane Potential and of Acetylcholine-evduced Currents in the Cell Body of the Cockroach Fast Coxal Depressor Motor Neurone

1990 ◽  
Vol 151 (1) ◽  
pp. 21-39 ◽  
Author(s):  
JONATHAN A. DAVID ◽  
DAVID B. SATTELLE
Keyword(s):  
Cell Body ◽  
Outward Current ◽  
Motor Neurone ◽  
Resting Potential ◽  
Inward Current ◽  
Current Voltage ◽  
Low K ◽  
Current Voltage Relationship ◽  
Ionic Basis ◽  
Voltage Relationship

The ionic basis of the resting potential and of the response to acetylcholine (ACh) has been investigated in the cell body membrane of the fast coxal depressor motor neurone in the metathoracic ganglion of the cockroach Periplaneta americana. By means of ion-sensitive microelectrodes, intracellular concentrations of three ion species were estimated (mmoll−1): [K+]i, 1443; [Na+]i, 9±1; [Cl−], 7±1. The resting potential of continuously superfused cells was −75.6±1.9mV at 22° C. A change in resting potential of 42.0±2.5mV accompanied a decade change in [K+]o. Experiments with (10−4moll−1) ouabain, Na+ injection, low temperature (10°C) and non-superfused cells indicated the presence of an electrogenic sodium pump. Under current-clamp, the cell body membrane was depolarized by sequentially applied, ionophoretic pulses (500ms duration) of ACh. Under voltage-clamp, such doses of ACh resulted in an inward current which was abolished in low-Na+ saline. Ion-sensitive electrodes revealed an increase in [Na+]i but no change in [Cl−1]j in response to externally applied ACh. The ACh-induced current-voltage relationship was shifted in a negative direction by low-K+ saline. The AChinduced inward current was usually followed by a delayed outward current which reversed at Ek. Low-K+ saline had the same effect on this outward component as depolarizing the membrane. This suggests that the outward current component is carried by K+. The ACh-induced inward current and the delayed outward current were potentiated either when [Ca2+]i was lowered by injecting the calcium chelator BAPTA or by exposure of the cell to low-Ca2+ saline. High-Ca2+ saline reduced the inward component of the response and produced a negative shift in the AChinduced current-voltage relationship. The amplitude of the delayed outward

A Time-Dependent Excitability change in the soma of an identified Insect Motoneurone

1992 ◽  
Vol 162 (1) ◽  
pp. 251-263
Author(s):  
JULES C. HANCOX ◽  
ROBERT M. PITMAN
Keyword(s):  
Cell Body ◽  
Action Potentials ◽  
Periplaneta Americana ◽  
Channel Blocker ◽  
Time Dependent ◽  
Sodium Channel Blocker ◽  
Plateau Potentials ◽  
Excitability Change ◽  
Membrane Oscillations

Long-term, current-clamp recordings were made from the cell body of the fast coxal depressor motoneurone (Df) of the third thoracic ganglion of the cockroach Periplaneta americana. In freshly dissected preparations the response to shortduration, suprathreshold, depolarising current pulses was a graded series of damped membrane oscillations similar to those reported previously in this neurone. The response to current injection changed, however, with increasing time after setting up the preparation: cells developed the ability to exhibit all-ornone action potentials. Their amplitude, however, was usually insufficient to overshoot 0 m V. Our observations suggest that the enhancement in excitability is dependent on time following dissection rather than on time following impalement. Recordings taken from neurone somata mechanically divided from their processes indicated that the time-dependent changes in excitability were not attributable to changes in synaptic input to the neurone and, moreover, that the cell body was involved in action potential genesis. The action potentials were resistant to treatment with the sodium channel blocker tetrodotoxin (up to 10−5 mol l−1), but were reversibly abolished when preparations were bathed in saline containing cadmium ions (1 mmol l−1) or manganese ions (20 or 40 mmol l−1) and, therefore, the inward current underlying these events was largely, if not entirely, carried by calcium ions. These time-dependent action potentials can co-exist with plateau potentials. In neurones giving both plateau potentials and time-dependent action potentials, plateau potentials can drive action potentials in bursts.

scholarly journals Ontogenesis of Presynaptic GABAB Receptor-Mediated Inhibition in the CA3 Region of the Rat Hippocampus

1998 ◽  
Vol 79 (3) ◽  
pp. 1341-1348 ◽  
Author(s):  
Olivier Caillard ◽  
Heather A. McLean ◽  
Yehezkel Ben-Ari ◽  
Jean-Luc Gaïarsa
Keyword(s):  
Pyramidal Neurons ◽  
Gabab Receptor ◽  
Hippocampal Slices ◽  
Reversal Potential ◽  
Rat Hippocampus ◽  
Dependent Manner ◽  
Paired Pulse ◽  
Ca3 Pyramidal Neurons ◽  
Paired Pulse Depression ◽  
Ca3 Region

Caillard, Olivier, Heather A. McLean, Yehezkel Ben-Ari, and Jean-Luc Gaı̈arsa. Ontogenesis of presynaptic GABAB receptor-mediated inhibition in the CA3 region of the rat hippocampus. J. Neurophysiol. 79: 1341–1348, 1998. γ-Aminobutyric acid-B(GABAB) receptor-dependent and -independent components of paired-pulse depression (PPD) were investigated in the rat CA3 hippocampal region. Intracellular and whole cell recordings of CA3 pyramidal neurons were performed on hippocampal slices obtained from neonatal (5–7 day old) and adult (27–34 day old) rats. Electrical stimulation in the hilus evoked monosynaptic GABAA postsynaptic currents (eIPSCs) isolated in the presence of the ionotropic glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 μM) and d(−)2-amino-5-phosphovaleric acid (d-AP5, 50 μM) with 2(triethylamino)- N-(2,6-dimethylphenyl) acetamine (QX314) filled electrodes. In adult CA3 pyramidal neurons, when a pair of identical stimuli was applied at interstimulus intervals (ISIs) ranging from 50 to 1,500 ms the amplitude of the second eIPSC was depressed when compared with the first eIPSC. This paired-pulse depression (PPD) was partially blockedb y  P - 3 - a m i n o p r o p y l - P - d i e t h o x y m e t h y l  p h o s p h o r i c  a c i d(CGP35348, 0.5 mM), a selective GABAB receptor antagonist. In neonates, PPD was restricted to ISIs shorter than 200 ms and was not affected by CGP35348. The GABAB receptor agonist baclofen reduced the amplitude of eIPSCs in a dose-dependent manner with the same efficiency in both adults and neonates. Increasing the probability of transmitter release with high Ca2+ (4 mM)/low Mg2+ (0.3 mM) external solution revealed PPD in neonatal CA3 pyramidal neurons that was 1) partially prevented by CGP35348, 2) independent of the membrane holding potential of the recorded cell, and 3) not resulting from a change in the reversal potential of GABAA eIPSCs. In adults the GABA uptake blocker tiagabine (20 μM) increased the duration of eIPSCs and the magnitude of GABAB receptor-dependent PPD. In neonates, tiagabine also increased duration of eIPSCs but to a lesser extent than in adult and did not reveal a GABAB receptor-dependent PPD. These results demonstrate that although GABAB receptor-dependent and -independent mechanisms of presynaptic inhibition are present onGABAergic terminals and functional, they do not operate at the level of monosynaptic GABAergic synaptic transmission at early stages of development. Absence of presynaptic autoinhibition of GABA release seems to be due to the small amount of transmitter that can access presynaptic regulatory sites.

scholarly journals Amyloid Precursor Protein (APP) and GABAergic Neurotransmission

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 550 ◽  
Author(s):  
Bor Luen Tang
Keyword(s):  
Amyloid Precursor Protein ◽  
Gabab Receptor ◽  
Reversal Potential ◽  
Proteolytic Processing ◽  
Precursor Protein ◽  
Mammalian Brain ◽  
Gabaergic Neurotransmission ◽  
Physiological Importance ◽  
Presynaptic Plasma Membrane ◽  
Etiological Agents

The amyloid precursor protein (APP) is the parent polypeptide from which amyloid-beta (Aβ) peptides, key etiological agents of Alzheimer’s disease (AD), are generated by sequential proteolytic processing involving β- and γ-secretases. APP mutations underlie familial, early-onset AD, and the involvement of APP in AD pathology has been extensively studied. However, APP has important physiological roles in the mammalian brain, particularly its modulation of synaptic functions and neuronal survival. Recent works have now shown that APP could directly modulate γ-aminobutyric acid (GABA) neurotransmission in two broad ways. Firstly, APP is shown to interact with and modulate the levels and activity of the neuron-specific Potassium-Chloride (K+-Cl−) cotransporter KCC2/SLC12A5. The latter is key to the maintenance of neuronal chloride (Cl−) levels and the GABA reversal potential (EGABA), and is therefore important for postsynaptic GABAergic inhibition through the ionotropic GABAA receptors. Secondly, APP binds to the sushi domain of metabotropic GABAB receptor 1a (GABABR1a). In this regard, APP complexes and is co-transported with GABAB receptor dimers bearing GABABR1a to the axonal presynaptic plasma membrane. On the other hand, secreted (s)APP generated by secretase cleavages could act as a GABABR1a-binding ligand that modulates presynaptic vesicle release. The discovery of these novel roles and activities of APP in GABAergic neurotransmission underlies the physiological importance of APP in postnatal brain function.

Ultrastructure of a sensillum associated with the pharynx of the cockroach Periplaneta americana

1996 ◽  
Vol 74 (11) ◽  
pp. 1999-2008
Author(s):  
R. Gary Chiang ◽  
K. G. Davey
Keyword(s):  
Electron Microscopy ◽  
Cell Body ◽  
Extracellular Space ◽  
Direct Contact ◽  
Periplaneta Americana ◽  
Sensory Cell ◽  
Sensory Cells ◽  
Osmotic Concentration ◽  
Sensory Cilia ◽  
Ultrathin Sections

A sensillum associated with the pharynx of the cockroach Periplaneta americana was examined in serial ultrathin sections using electron microscopy. This sensillum consisted of a group of 10–20 similar sensillar subunits. Each sensillar subunit possessed one 60- to 70-μm long dendritic sheath that made direct contact with the cuticle. The dendritic sheath enclosed 3–5 sensory cilia arising from 3–5 sensory cells located in a cluster approximately 30 μm proximal to the base of the sheath. Between the sensory cell body and the base of the sheath the dendrites were wrapped by the sheath-forming cell. Before entering the dendritic sheath itself, the dendrites crossed through an extracellular space, the ciliary sinus. No cuticular specializations, such as a well-defined sensory hair or pore, were observed. The structure of this sensillum suggests that it responds poorly to mechanical distortion of its surroundings. This characteristic supports the hypothesis that this sensillum measures the osmotic concentration of the ingested food.

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