Inhibitory Component of the Resistance Reflex in the Locomotor Network of the Crayfish

2002 ◽  
Vol 88 (5) ◽  
pp. 2575-2588 ◽  
Author(s):  
Morgane Le Bon-Jego ◽  
Daniel Cattaert
Keyword(s):  
Sensory Nerve ◽  
Chloride Concentration ◽  
Chordotonal Organ ◽  
Bathing Solution ◽  
Postsynaptic Potentials ◽  
Inhibitory Pathways ◽  
In Series ◽  
Chloride Channel Blocker ◽  
Inhibitory Components

The aim of this study was to investigate the inhibitory components of a resistance reflex in the walking system of the crayfish. This study was performed using an in vitro preparation of several thoracic ganglia including motor nerves and the proprioceptor that codes movements of the second joint (coxo-basipodite chordotonal organ—CBCO). Sinusoidal movements were imposed on the CBCO, and intracellular responses were recorded from levator (Lev) and depressor (Dep) motoneurons (MNs). We found that in MNs that oppose the imposed movements (e.g., the Lev MNs during the imposed downward movement), the response consists in a depolarization resulting from the summation of excitatory postsynaptic potentials (EPSPs). A movement in the opposite direction resulted in hyperpolarization during which inhibitory postsynaptic potentials (IPSPs) summated. The inhibitory pathway to each MN is oligosynaptic (i.e., composed of a small number of neurons in series) and involves spiking interneurons because it was blocked in the presence of a high-divalent cation solution. The IPSPs were mediated by a chloride conductance because their amplitude was sensitive to the chloride concentration of the bathing solution and because they were blocked by the chloride channel blocker, picrotoxin. Resistance reflex IPSPs related to single CBCO neurons could be identified. These unitary IPSPs were blocked in the presence of 3-mercapto-propionic acid, an inhibitor of gamma-amino-butyric acid (GABA) synthesis, indicating that they are mediated by GABA. In addition to this GABAergic pathway, electrical stimulation of the CBCO sensory nerve induced compound IPSPs that were blocked by glutamate pyruvate transaminase (GPT), indicating the presence of glutamatergic inhibitory pathways. These glutamatergic interneurons do not appear to be involved in the resistance reflex, however, as GPT did not block the unitary IPSPs. Functionally, the resistance reflex is mainly supported by movement-coding CBCO sensory neurons. We demonstrate that such movement-coding CBCO neurons produce both monosynaptic EPSPs in the MNs opposing imposed movements and oligosynaptic IPSPs in the antagonistic motoneurons. These results highlight the similarities between the inhibitory pathways in resistance reflex of the crayfish and in the stretch reflex of vertebrates mediated by Ia inhibitory interneurons.

scholarly journals In Vivo Analysis of Proprioceptive Coding and Its Antidromic Modulation in the Freely Behaving Crayfish

2005 ◽  
Vol 94 (2) ◽  
pp. 1013-1027 ◽  
Author(s):  
Didier Le Ray ◽  
Denis Combes ◽  
Cyril Déjean ◽  
Daniel Cattaert
Keyword(s):  
Motor Activity ◽  
Action Potentials ◽  
Physiological State ◽  
Sensory Nerve ◽  
Sensory Nerves ◽  
Chordotonal Organ ◽  
Electromyographic Activity ◽  
Sensory Coding ◽  
Freely Behaving

Although sensory nerves in vitro are known to convey both orthodromic (sensory) and antidromic (putatively modulating) action potentials, in most cases very little is known about their bidirectional characteristics in intact animals. Here, we have investigated both the sensory coding properties and antidromic discharges that occur during real walking in the freely behaving crayfish. The activity of the sensory nerve innervating the proprioceptor CBCO, a chordotonal organ that monitors both angular movement and position of the coxo-basipodite (CB) joint, which is implicated in vertical leg movements, was recorded chronically along with the electromyographic activity of the muscles that control CB joint movements. Two wire electrodes placed on the sensory nerve were used to discriminate orthodromic from antidromic action potentials and thus allowed for analysis of both sensory coding and antidromic discharges. A distinction is proposed between 3 main classes of sensory neuron, according to their firing in relation to levator muscle activity during free walking. In parallel, we describe 2 types of antidromic activity: one produced exclusively during motor activity and a second produced both during and in the absence of motor activity. A negative correlation was found between the activity of sensory neurons in each of the 3 classes and identified antidromic discharges during walking. Finally, a state-dependent plasticity of CBCO nerve activity has been found by which the distribution of sensory orthodromic and antidromic activity changes with the physiological state of the biomechanical apparatus.

In Vitro Investigation of Synaptic Relations Between Interneurons Surrounding the Trigeminal Motor Nucleus and Masseteric Motoneurons

1997 ◽  
Vol 78 (3) ◽  
pp. 1720-1725 ◽  
Author(s):  
Arlette Kolta
Keyword(s):  
Motor Nucleus ◽  
Trigeminal Motor Nucleus ◽  
Postsynaptic Potentials ◽  
In Vitro Investigation ◽  
Reciprocal Connections ◽  
Trigeminal Motoneurons ◽  
Inhibitory Components ◽  
Premotor Areas ◽  
Stimulation Of

Kolta, Arlette. In vitro investigation of synaptic relations between interneurons surrounding the trigeminal motor nucleus and masseteric motoneurons. J. Neurophysiol. 78: 1720–1725, 1997. Because of their many inputs and bilateral projections, interneurons surrounding the trigeminal motor nucleus (MotV) are thought to be very important in control of jaw movements and reflexes. However, their interactions with the trigeminal motoneurons are almost unknown. In the present study an in vitro slice preparation was used to investigate this relationship in rat. The zone bordering MotV has been subdivided into four regions: the supra-, juxta-, and intertrigeminal areas (SupV, JuxtV, and IntV, respectively) and the parvocellular reticular formation ventral and caudal to MotV. Stimulation of all areas evoked short-latency excitatory postsynaptic potentials (EPSPs) in masseteric motoneurons. Frequently the EPSPs masked inhibitory postsynaptic potentials (IPSPs) or were followed by long-lasting inhibitory potentials. Only responses obtained from stimulation of JuxtV and IntV seemed devoid of inhibitory components. The EPSPs were mediated through kainate/α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, whereas the IPSPs appear to be due to γ-aminobutyric acid and glycine. EPSPs and IPSPs were also recorded in SupV premotor interneurons after stimulation of IntV and MotV, respectively, thus suggesting that reciprocal connections exist between premotor areas and also between premotor interneurons of SupV and inhibitory interneurons located within MotV. It is concluded that the preparation used here will doubtless prove useful for further investigation of the circuitry involved in the bilateral coordination of the jaw.

Electrolyte secretion from rabbit pancreas in vitro

1965 ◽  
Vol 208 (6) ◽  
pp. 1171-1176 ◽  
Author(s):  
S. S. Rothman ◽  
F. P. Brooks
Keyword(s):  
Carbon Dioxide ◽  
Pancreatic Secretion ◽  
Chloride Concentration ◽  
Carbon Dioxide Concentration ◽  
Total Carbon ◽  
Bathing Solution ◽  
Vascular Perfusion ◽  
Secretory Rate ◽  
Plasma Filtration

A technic has been developed permitting direct collection of undiluted rabbit pancreatic secretion in vitro without vascular perfusion. The rates of secretion and output of electrolytes were comparable to those obtained in situ. When secretin was added, flow and bicarbonate concentration increased. Secretion in vitro ceased when inhibitors of glycolysis and aerobic metabolism were added to the bathing solution. The sodium concentration of the secretion exceeded that of the bathing solution in all but one observation. Potassium concentrations in secretion were linearly related (slope = 0.93) to the potassium concentration in the bath over a range of 5.8–12.0 mm. After 4–5 hr in vitro, the total carbon dioxide concentration of secretion had decreased while chloride concentration increased with no significant change in the rate of secretion. When secretory rate changed over a range of approximately 30–600 µliters/hr, chloride and carbon dioxide output varied directly with the rate of secretion. The osmolarity of the bathing solution and secretion were always equivalent. These results are incompatible with direct plasma filtration and bicarbonate-chloride exchange as the main mechanisms of pancreatic secretion.

Excitatory postsynaptic potentials recorded from regular-spiking cells in layers II/III of rat sensorimotor cortex

1992 ◽  
Vol 67 (3) ◽  
pp. 728-737 ◽  
Author(s):  
G. G. Hwa ◽  
M. Avoli
Keyword(s):  
Nmda Receptor Antagonist ◽  
Short Latency ◽  
Neuronal Membrane ◽  
Dependent Manner ◽  
Excitatory Postsynaptic Potentials ◽  
Normal Medium ◽  
Postsynaptic Potentials ◽  
Extracellular Stimuli ◽  
Relationship Of

1. Intracellular recording techniques were used to investigate the physiological and pharmacological properties of stimulus-induced excitatory postsynaptic potentials (EPSPs) recorded in regular-spiking cells located in layers II/III of rat sensorimotor cortical slices maintained in vitro. 2. Depending on the strength of the extracellular stimuli, a pure EPSP or an EPSP-inhibitory postsynaptic potential sequence was observed under perfusion with normal medium. The EPSPs displayed short latency of onset [2.4 +/- 0.7 (SD) ms] and were able to follow repetitive stimulation (tested less than or equal to 5 Hz). Variation of the membrane potential (Vm) revealed two types of voltage behavior for the short-latency EPSP. The first type decreased in amplitude with depolarization and increased in amplitude with hyperpolarization. In contrast, the second type behaved anomalously by increasing and decreasing in size after depolarization and hyperpolarization, respectively. 3. Several experimental procedures were carried out to investigate the mechanism underlying the anomalous voltage behavior of the EPSP. Results indicated that this type of Vm dependency could be mimicked by an intrinsic response evoked by a brief pulse of depolarizing current and could be abolished by N-(2,6-dimethylphenylcarbamoylmethyl)triethylammonium bromide (50 mM). Furthermore, the EPSP was not sensitive to the N-methyl-D-aspartate (NMDA) receptor antagonist 3-((+-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonate (CPP, 10 microM). Thus the anomalous voltage relationship of the neuronal membrane. 4. The involvement of non-NMDA receptors in excitatory synaptic transmission was investigated with their selective antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 1-10 microM). This drug greatly reduced or completely blocked the EPSP in a dose-dependent manner (1-10 microM). The IC50 for the CNQX effect was approximately 2 microM. In the presence of CNQX (10 microM) and glycine (10 microM), synaptic stimulation failed to elicit firing of action potential. However, a CPP-sensitive EPSP was observed. 5. When synaptic inhibition was reduced by low concentration of bicuculline methiodide (BMI, 1-2 microM), extracellular stimulation revealed late EPSPs (latency to onset: 10-30 ms) that were not discernible in normal medium. Similar to the short-latency EPSP, the Vm dependency displayed by this late EPSP could be modified by inward membrane rectifications. The late EPSP appeared to be polysynaptic in origin because 1) its latency of onset was long and variable and 2) it failed to follow repetitive stimuli delivered at a frequency that did not depress the short-latency EPSP.(ABSTRACT TRUNCATED AT 400 WORDS)

A new muscle receptor organ in the antenna of the rock lobster Palinurus vulgaris : mechanical, muscular and proprioceptive organization of the two proximal joints J0 and J1

1983 ◽  
Vol 218 (1210) ◽  
pp. 95-110 ◽  
Keyword(s):  
Anterior Part ◽  
Proximal Part ◽  
The Other ◽  
Chordotonal Organ ◽  
Excitatory Postsynaptic Potentials ◽  
Rock Lobster ◽  
Postsynaptic Potentials ◽  
Muscle Receptor ◽  
Physiological Properties ◽  
Receptor Organ

(i) Following previous work on the morphological and physiological properties of the two distal joints (J2, J3) of the atenna of the rock lobster Palinurus vulgaris , the mechanical, muscular and proprioceptive organization of the two proximal joints between the antennal segments S1 and S2 (J1) and between S1 and the cephalothorax (J0) have now been studied. (ii) Articulated by two classical condyles, J1 moves in a mediolateral plane. One external rotator muscle (ER) and three internal rotator muscles (IR1, IR2, IR3) subserve its movements. J0 is articulated by two different systems: a classical ventrolateral condyle and a complex sliding system constituted by special cuticular structures on the dorsomedial side of the S1 segment and on the rostrum between the two antennae. J0 moves in the dorsoventral plane by means of a levator muscle (Lm) and a depressor muscle (Dm). A third muscle, the lateral tractor muscle (LTm), associated with J0 and lying obliquely across S1, may modulate the level of friction between the S1 segment and the rostrum. (iii) Proprioception in J1 is achieved by a muscle receptor organ AMCO-J1 (antennal myochordotonal organ for the J1 joint) associating a small accessory muscle (S1.am) located in the proximal part of the S1 segment and a chordotonal organ inserted proximally on the S1.am muscle and distally on the S2 segment. J0 proprioception is ensured by a simple chordotonal organ (CO-J0) located in the anterior part of the cephalothorax. (iv) The S1.am muscle is innervated by three motoneurons characterized by their very small diameters and inducing respectively tonic excitatory postsynaptic potentials, phasic excitatory postsynaptic potentials and inhibitory postsynaptic potentials. Anatomical and physiological observations suggest functional correlation between S1.am and IR1 motor innervation. (v) Mechanical and muscular organization of J0 and J1 are compared with that of the other joints of the antenna. The properties of the AMCO-J1 proprioceptor are discussed in relation to the other muscle receptor organs described in crustaceans.

Connections between thoraco-coxal proprioceptive afferents and motor neurons in the locust

2000 ◽  
Vol 203 (3) ◽  
pp. 435-445
Author(s):  
M. Wildman
Keyword(s):  
Electrical Stimulation ◽  
Sensory Neurons ◽  
Motor Neurons ◽  
Chordotonal Organ ◽  
Synaptic Connections ◽  
Afferent Neurons ◽  
Postsynaptic Potentials ◽  
The Common ◽  
Proprioceptive Afferents ◽  
Stimulation Of

The position of the coxal segment of the locust hind leg relative to the thorax is monitored by a variety of proprioceptors, including three chordotonal organs and a myochordotonal organ. The sensory neurons of two of these proprioceptors, the posterior joint chordotonal organ (pjCO) and the myochordotonal organ (MCO), have axons in the purely sensory metathoracic nerve 2C (N2C). The connections made by these afferents with metathoracic motor neurons innervating thoraco-coxal and wing muscles were investigated by electrical stimulation of N2C and by matching postsynaptic potentials in motor neurons with afferent spikes in N2C. Stretch applied to the anterior rotator muscle of the coxa (M121), with which the MCO is associated, evoked sensory spikes in N2C. Some of the MCO afferent neurons make direct excitatory chemical synaptic connections with motor neurons innervating the thoraco-coxal muscles M121, M126 and M125. Parallel polysynaptic pathways via unidentified interneurons also exist between MCO afferents and these motor neurons. Connections with the common inhibitor 1 neuron and motor neurons innervating the thoraco-coxal muscles M123/4 and wing muscles M113 and M127 are polysynaptic. Afferents of the pjCO also make polysynaptic connections with motor neurons innervating thoraco-coxal and wing muscles, but no evidence for monosynaptic pathways was found.

Experimental Analysis of Pulsatile Flow Through Elastic Collapsible Tubes: Application to Cardiac Assist Device

1990 ◽  
Vol 112 (1) ◽  
pp. 75-79 ◽  
Author(s):  
O. Lichtenstein ◽  
U. Dinnar
Keyword(s):  
Systemic Circulation ◽  
Aortic Pressure ◽  
Assist Device ◽  
Cardiac Assist ◽  
Cardiac Assist Device ◽  
Non Invasive ◽  
Failing Heart ◽  
In Series ◽  
Vitro Analysis

This study presents a simulated analysis of Phased Compression Cardiac Assist Device (PCCAD) and evaluation of its applicability as a non-invasive temporary assist for a failing heart. The new technique is based on the chest pump mechanism for blood flow augmentation during external massage by phased compression of the abdominal and thoracic cavities. A semi-closed hydraulic system to simulate the systemic circulation was constructed; the system includes a left ventricle which functions according to the Starling principle and a pneumatic system which controls the pressures applied to the thoracic and abdominal cavities, in complete synchronization with the beating normal or failing heart. The possibility of manipulating the three pumps in series (venous, heart, and arterial) has been checked, and the principal parameters which effect the efficiency of the PCCAD were evaluated. This in-vitro analysis shows the high potential of a non-invasive temporary cardiac assist device. It points to the necessary measures one has to take in order to achieve good synchronization and to interfere externally with the augmentation of cardiac output or with the augmentation of root aortic pressure.

Effect of pH on chloride absorption in the flounder intestine

1988 ◽  
Vol 255 (2) ◽  
pp. G247-G252 ◽  
Author(s):  
A. N. Charney ◽  
J. I. Scheide ◽  
P. M. Ingrassia ◽  
J. A. Zadunaisky
Keyword(s):  
Small Intestine ◽  
Short Circuit ◽  
Ph Effect ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Solution Ph ◽  
Transport Pathway ◽  
Ussing Chambers ◽  
Chloride Absorption ◽  
In Series

Chloride absorption in the small intestine of the winter flounder, Pseudopleuronectes americanus, is reported to be sensitive to ambient pH. We studied this sensitivity in isolated stripped intestinal mucosa mounted in modified Ussing chambers. Unidirectional 36Cl fluxes (JClm----s, JCls----m) were measured under short-circuited conditions in bathing solutions containing various combinations of HCO3- (0-20 mM), partial pressure of CO2 (0-36 mmHg), and pH (6.77-7.85). We found that JClm----s, net 36Cl flux (JClnet), and short-circuit current (Isc) increased and JCls----m decreased predominately in response to increases in bathing solution pH. There was a linear relationship between pH and both JClnet (r = 0.92, P less than 0.01) and Isc (r = 0.96, P less than 0.005) between pH 6.77 and 7.74. The pH effect was completely reversible, did not require either CO2 or HCO3-, and was not affected by the presence of mucosal barium at 1 mM. Mucosal bumetanide (0.1 mM) completely inhibited the pH effect. These data suggest that the process by which Cl- is absorbed in the flounder intestine is sensitive to pH. The data do not indicate whether pH affects Na+-K+-2Cl- cotransport or a Cl- transport pathway in series with this process. The direction of Cl- absorption in response to pH contrasts with inverse relation of pH and Cl- absorption in mammalian small intestine.

Sign in / Sign up

Export Citation Format

Share Document