Reflexes Mediated by Non-Impulsive Afferent Neurones of Thoracic-Coxal Muscle Receptor Organs in the Crab, Carcinus Maenas: I. Receptor Potentials and Promotor Motoneurone Responses

1980 ◽  
Vol 86 (1) ◽  
pp. 275-303
Author(s):  
A. J. CANNONE ◽  
B. M. H. BUSH
Keyword(s):  
Carcinus Maenas ◽  
Receptor Potential ◽  
Reflex Response ◽  
Shore Crab ◽  
Sensory Fibre ◽  
Muscle Receptor ◽  
Receptor Organ ◽  
Length Changes ◽  
Receptor Muscle

Address for reprints. 1. A preparation of the thoracic-coxal muscle receptor organ of the posterior leg of the shore crab, in which central synaptic efficacy of the sensori-motor reflex pathways is maintained for long periods, is described. 2. The reflex response to receptor muscle stretch commonly involves three promotor motoneurones, designated Pm1-3 in order of their recruitment. 3. Motoneurone Pm1, and less frequently Pm2 and Pm3, may be tonically active during maintained receptor length changes within the in situ length range of the receptor muscle. 4. The following observations suggest that the T rather than the S sensory fibre provides the afferent drive onto reflexly activated promotor motoneurones: selective section of the S or T sensory fibres; frequency ‘envelopes’ of individual motoneurone responses to trapezoid stretch stimuli, including features such as adaptation and velocity sensitivity of the reflex response; and the ‘hysteresis’ in the response to increasing followed by decreasing receptor length changes, with or without superimposed trapezoid stretch stimuli. 5. The initial reflex response to ramp stretch can be directly related to the complex ‘initial component’ of the T fibre receptor potential waveform. This comprises a variable spiky alpha (α) component, followed by a longer duration, more predictable beta (β) component, which depends upon stimulus parameters such as stretch velocity and the length and tension of the receptor muscle at the onset of stretch. 6. In the de-efferented receptor muscle, changes in compliance or ‘tonus’ resulting from receptor manipulation have a marked effect on the sensory, and hence reflex, response to stretch. As this would have profound implications for the functioning of this muscle receptor organ in vivo, a role for the receptor motor innervation in counteracting any such response variability seems likely.

Reflexes Mediated by Non-Impulsive Afferent Neurones of Thoracic-Coxal Muscle Receptor Organs in the Crab, Carcinus Maenas: II. Reflex Discharge Evoked by Current Injection

1980 ◽  
Vol 86 (1) ◽  
pp. 305-331
Author(s):  
A. J. CANNONE ◽  
B. M. H. BUSH
Keyword(s):  
Carcinus Maenas ◽  
Reflex Response ◽  
Experimental Conditions ◽  
Maximum Slope ◽  
Sensory Fibre ◽  
Reflex Pathways ◽  
Unknown Property ◽  
Voltage Frequency ◽  
Receptor Muscle

Address for reprints. 1. Injection of depolarizing and hyperpolarizing currents into the nonimpulsive S and T sensory fibres has allowed a quantitative analysis of the input-output relationships of this sensory-reflex system. 2. Graded depolarization of the T fibre typically results in sigmoid voltage-frequency relationships for motoneurones Pm1–3, the maximum ‘slopes’ in the most sensitive preparation being 31, 47.5 and 33 Hz/mV respectively, without taking into account further afferent attenuation within the thoracic ganglion. 3. Graded depolarizations of the S fibre recruit four motoneurones Pmi-4 common to the T fibre reflex pathway, although activation thresholds are much higher and the maximum slope or ‘gain’ of the voltage frequency relationships is much reduced compared to that of the T fibre reflex pathways. Thus, although the S fibre synapses either directly or indirectly with promotor motoneurones, typical 5–10 mV stretch-induced receptor potentials remain sub-threshold for a contribution to the reflex output, albeit under experimental conditions and at all but the most extended receptor muscle lengths. 4. Differentiating between motor impulse amplitudes, and using simultaneously recorded promotor muscle junction potentials as a further aid, establishes at least nine motoneurones as being reflexly recruited by the S and T fibres: Pm1–8 by the T fibre and Pm1–4 and Pm9 by the S fibre. 5. Hyperpolarization of the T and S fibres confirms that ongoing tonic motor activity is peripherally determined by receptor length prescribed T fibre ‘resting’ potentials, rather than by the more linearly related S fibre ‘resting’ potentials at different receptor muscle lengths. Moreover, suppression of the reflex response by sensory fibre hyperpolarizations coincident with stretch stimuli leaves little doubt that it is the T rather than the S fibre that provides the sensory drive for the stretch reflex in vitro. 6. By using long duration, constant value T fibre depolarizing potentials, the postsynaptic component of adaptation for Pm1–3 has been found to be slight, in contrast to the more rapid adaptation of the higher threshold Pm 5–8 motoneurones. Moreover, adaptation rates for Pm 1–3 discharges are lower the smaller the afferent drive. It is suggested therefore that reflexly activated promotor MNs can be differentiated into ‘tonic’ and ‘phasic’ categories. 7. Motoneurone Pm2 sometimes discharges in the form of ‘rigid’ (7–8 ms intervals) impulse couplets. At low mean reflex frequencies all Pm2 impulses are locked into couplets (‘complete’ patterning). While both ‘rigid’ and ‘complete’ patterning break down abruptly as mean frequencies increase, re-establishment is more gradual (hysteretic) with decreasing mean frequencies. Patterning, albeit a particularly labile phenomenon, is almost certainly an intrinsic, if unknown, property of the motoneurone itself.

PROPRIOCEPTIVE INPUT FROM TWO BASAL JOINT STRETCH RECEPTORS TO LEG MOTONEURONES IN THE ISOLATED THORACIC GANGLION OF THE SHORE CRAB

1992 ◽  
Vol 163 (1) ◽  
pp. 187-208
Author(s):  
STEWART I. HEAD ◽  
BRIAN M.H. BUSH
Keyword(s):  
Motor Nerve ◽  
Carcinus Maenas ◽  
Thoracic Ganglion ◽  
Shore Crab ◽  
Chordotonal Organ ◽  
Leg Muscles ◽  
Receptor Organ ◽  
Motor Nerves

The reflex effects and interactions of two proprioceptors upon motoneurones supplying the four basal leg muscles of the shore crab Carcinus maenas have been studied in a new in vitro preparation consisting of the thoracic-coxal muscle receptor organ (TCMRO) and the coxo-basal chordotonal organ (CBCO) isolated together with the whole thoracic ganglion complex to which they were still connected by their afferent nerves. Each receptor strand was stimulated mechanically, while recording intracellularly from motoneurones in the ganglion, and extracellularly from the cut motor nerves innervating the promotor and remotor muscles of the thoracic-coxal (T—C) joint and the levator and depressor muscles of the coxo-basal (C—B) joint. Stretch of the TCMRO evoked reflex firing in several units in the promotor motor nerve, confirming previous studies. In addition to this ‘intrajoint’ reflex, however, TCMRO stretch also elicited ‘interjoint’ reflex responses in motoneurones of both the levator and depressor muscles. Similarly, stretch and release of the CBCO produced intrajoint resistance reflexes in levator and depressor motoneurones, respectively, as well as interjoint reflexes in promotor and remotor motoneurones. In general, the CBCO produced stronger reflex effects in all four motor nerves than did the TCMRO. Intracellular recordings from individual motoneurones of all four muscles revealed that the majority of them received convergent input from both proprioceptors. The importance of such convergent input in vivo is discussed

Sensory feedback and central afferent interaction in the muscle receptor organ of the crab, Carcinus maenas

1996 ◽  
Vol 76 (2) ◽  
pp. 788-798 ◽  
Author(s):  
M. Wildman ◽  
A. Cannone
Keyword(s):  
Action Potentials ◽  
Sensory Feedback ◽  
Carcinus Maenas ◽  
Small Diameter ◽  
Sensory Response ◽  
Fiber Direction ◽  
Single Action ◽  
Muscle Receptor ◽  
Leg Muscles ◽  
Receptor Organ

1. An interaction exists between two proprioceptive afferent neurons innervating the thoracic-coxal muscle receptor organ (TCMRO) of the crab, Carcinus maenas. Intracellular recordings were made from the extraganglionic regions of the afferents in order to characterize this interaction and its effects on sensory feedback. 2. A current-induced depolarization of the nonspiking T fiber of the TCMRO results in a depolarization of the P fiber, a small-diameter (7 microns) neuron innervating the same receptor. This interaction is graded in amplitude, and may result in a single action potential being superimposed on the graded response of the P fiber. A hyperpolarization of the T fiber has a smaller effect on the P fiber than a depolarization of similar amplitude. The interaction is rectified in a T- to P-fiber direction, and has a minimum central delay of approximately 3.6 ms. 3. The site of the interaction between the afferents is situated centrally, within the thoracic ganglion. Action potentials evoked in the P fiber by a T-fiber depolarization propagate actively and antidromically to the periphery. 4. Central modulation of the interaction occurs, because the amplitude of a T-fiber-induced depolarization is reduced in the P fiber during centrally generated spontaneous bursts of activity in the motoneurons of basal leg muscles. 5. Because of the interaction between T and P fibers, action potentials recorded from the peripheral portion of the P fiber during receptor stretch may be either orthodromic, resulting directly from the effects of the stretch on the sensory endings of the P fiber, or antidromic, resulting from the central input from the T fiber. 6. The T- to P-fiber interaction may serve to extend the dynamic sensitivity range of the P fiber, in particular by amplifying its sensory response at short receptor lengths and low velocities of stretch.

Cardiac performance in semi-isolated heart of the crab Carcinus maenas

1994 ◽  
Vol 266 (3) ◽  
pp. R781-R789
Author(s):  
J. L. Wilkens ◽  
B. R. McMahon
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Isolated Heart ◽  
Carcinus Maenas ◽  
Ventricular Volume ◽  
Whole Body ◽  
Shore Crab ◽  
Stroke Work ◽  
Adaptive Responses

A semi-isolated, in situ heart preparation of the shore crab, Carcinus maenas, supported by its alary ligaments, pumps vigorously for hours at a mean heart rate of 49.7 beats/min and cardiac output of 30 ml.kg-1.min-1. These hearts show no adaptive responses to changes in pericardial sinus pressure, outflow resistance, or afterload. Direct perfusion-induced stretch of the heart wall causes increases in contractile force but minimal changes in heart rate. Stroke work and power are lower than comparable values for animals with myogenic hearts and closed circulatory systems. The values for heart rate and cardiac output are lower than in vivo values and may in part reflect the technique used as well as intrinsic performance of the heart without neural and neurohormonal inputs. Morphometrically the heart represents 0.2% of whole body weight, and the mean stroke volume of 0.35-0.45 ml/kg represents an ejection fraction of 27-34% of ventricular volume (1.4 ml/kg).

The Uptake of Cadmium Into the Haemolymph of the Shore Crab Carcinus Maenas: The Relationship With Copper and Other Divalent Cations

1977 ◽  
Vol 67 (1) ◽  
pp. 147-161
Author(s):  
D. A. WRIGHT
Keyword(s):  
Divalent Cations ◽  
Cadmium Concentration ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Cadmium Level ◽  
Haemolymph Protein ◽  
Urine Cadmium ◽  
The Relationship

When Carcinus was exposed to 20 μ-mol l−1 cadmium, the haemolymph cadmium level was initially dependent upon the salinity of the external medium. After 14 days the mean haemolymph cadmium level in 50% s.w. animals was nearly twice that of 100% s.w. animals. This trend was not sustained, however, and the situation was complicated by occasional inconsistent values. In both in vivo and in vitro conditions nearly all the haemolymph cadmium becomes bound to haemolymph protein within a few days. The relationship between haemolymph cadmium, copper and protein concentration has been investigated. Although the latter are highly correlated with each other, cadmium formed a significant positive relationship with haemolymph copper (r = 0.523) and protein (r = 0.533) only after 3–4 weeks uptake. Exposure to 20 μ-mol l−1 cadmium has no obvious effects on haemolymph protein and copper concentrations, which are clearly dependent on feeding status. Mortalities among experimental animals were often preceded by a rise in haemolymph cadmium concentration. This is usually seen before there are any obvious signs of tissue breakdown. Urine cadmium loss is probably unimportant as a pathway for the elimination of this metal. Urine cadmium concentrations often exceeded serum cadmium levels indicating that cadmium may sometimes be eliminated in bound form.

Reversal of a Walking Leg Reflex Elicited by a Muscle Receptor

1981 ◽  
Vol 90 (1) ◽  
pp. 197-203
Author(s):  
R. A. DiCAPRIO ◽  
F. CLARAC
Keyword(s):  
Carcinus Maenas ◽  
Passive Movement ◽  
Reflex Activity ◽  
Shore Crab ◽  
Central State ◽  
Muscle Receptor ◽  
State Of Activity

Passive movement of the basal (thoracic-coxal) leg joint in the shore crab Carcinus maenas normally elicits a resistance reflex in the promotor and remotor motoneurones. Remotion of the joint excites promotor moto-neurones and promotion excites remotor motoneurones. This reflex behaviour may reverse and become an assistance reflex, where movement of the joint excites the motoneurones innervating the muscle which would assist the passive movement. This reversal of reflex activity appears to be dependent upon the central state of activity of the animal.

scholarly journals Crustacean hyperglycaemic hormone (CHH)-like peptides and CHH-precursor-related peptides from pericardial organ neurosecretory cells in the shore crab, Carcinus maenas, are putatively spliced and modified products of multiple genes

2001 ◽  
Vol 356 (1) ◽  
pp. 159-170 ◽  
Author(s):  
Heinrich DIRCKSEN ◽  
Detlef BÖCKING ◽  
Uwe HEYN ◽  
Christa MANDEL ◽  
J. Sook CHUNG ◽  
...  
Keyword(s):  
Signal Peptide ◽  
Carcinus Maenas ◽  
Penaeid Shrimp ◽  
Neurosecretory Cells ◽  
Shore Crab ◽  
Amino Acid Peptide ◽  
C Terminus ◽  
Gene Structures

About 24 intrinsic neurosecretory neurons within the pericardial organs (POs) of the crab Carcinus maenas produce a novel crustacean hyperglycaemic hormone (CHH)-like peptide (PO-CHH) and two CHH-precursor-related peptides (PO-CPRP I and II) as identified immunochemically and by peptide chemistry. Edman sequencing and MS revealed PO-CHH as a 73 amino acid peptide (8630Da) with a free C-terminus. PO-CHH and sinus gland CHH (SG-CHH) share an identical N-terminal sequence, positions 1–40, but the remaining sequence, positions 41–73 or 41–72, differs considerably. PO-CHH may have different precursors, as cDNA cloning of PO-derived mRNAs has revealed several similar forms, one exactly encoding the peptide. All PO-CHH cDNAs contain a nucleotide stretch coding for the SG-CHH41–76 sequence in the 3′-untranslated region (UTR). Cloning of crab testis genomic DNA revealed at least four CHH genes, the structure of which suggest that PO-CHH and SG-CHH arise by alternative splicing of precursors and possibly post-transcriptional modification of PO-CHH. The genes encode four exons, separated by three variable introns, encoding part of a signal peptide (exon I), the remaining signal peptide residues, a CPRP, the PO-CHH1–40/SG-CHH1–40 sequences (exon II), the remaining PO-CHH residues (exon III) and the remaining SG-CHH residues and a 3′-UTR (exon IV). Precursor and gene structures are more closely related to those encoding related insect ion-transport peptides than to penaeid shrimp CHH genes. PO-CHH neither exhibits hyperglycaemic activity in vivo, nor does it inhibit Y-organ ecdysteroid synthesis in vitro. From the morphology of the neurons it seems likely that novel functions remain to be discovered.

In vivo effects of serotonin and fluoxetine on cardio-ventilatory functions in the shore crab Carcinus maenas (L. 1758)

2019 ◽  
Vol 207 ◽  
pp. 132-141 ◽  
Author(s):  
Alexandrine Robert ◽  
Tiphaine Monsinjon ◽  
Romain Péden ◽  
Virginie Rasoamampianina ◽  
Jean-Claude Le Mével ◽  
...  
Keyword(s):  
Carcinus Maenas ◽  
Shore Crab ◽  
In Vivo Effects
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