Physiological and anatomical properties of Leydig cells in the segmental nervous system of the leech

Keyser, Kent T.; Frazer, Bryan M.; Lent, Charles M.

doi:10.1007/bf00612707

Cited by 24 publications

(24 citation statements)

References 16 publications

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“…When the spontaneously active Leydig neuron (Keyser et al, 1982) was hyperpolarized with a negative current pulse, the glial cell slowly depolarized , suggesting a tonic influence of Leydig neurons with a low spontaneous activity on the glial membrane potential. To keep this tonic influence at a low rate, the Leydig activity was decreased (Ͻ0.5 Hz) or totally suppressed by constant hyperpolarizing current injection.…”

Section: Electrophysiologymentioning

confidence: 98%

“…1A). They are electrically and dye-coupled (Keyser et al, 1982) (Fig. 1C), and immunoreactive to a myomodulin-like peptide (Keating and Sahley, 1996).…”

Section: Morphological Relations Between Leydig Cells and Giant Glialmentioning

confidence: 99%

“…Assuming a cell soma diameter of 45 m (Keyser et al, 1982), the amount of TEA calculated to be in the cell body at the offset of injection was ϳ100 mM, which would then decline as a result of diffusion into the axon and numerous dendrites. The duration of the action potential and of the evoked glial current was measured at their half-maximum amplitude, respectively.…”

Section: Injection Of Teamentioning

confidence: 99%

“…The anatomy and some ultrastructural features of the Leydig neurons were first described by Keyser et al (1982), using horseradish peroxidase (HRP) and Lucifer Yellow staining and electron micrographs. It was shown that the Leydig neurons are not only electrically, but also dye-coupled to the contralateral and the adjacent ganglionic counterparts.…”

Section: Morphological Relationships Between Leydig Neurons and Giantmentioning

confidence: 99%

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Characterization of a synaptiform transmission between a neuron and a glial cell in the leech central nervous system

Britz

Lohr

Schmidt

et al. 2002

Glia

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The cross-talk between neurons and glial cells is receiving increased attention because of its potential role in information processing in nervous systems. Stimulation of a single identifiable neuron, the neurosecretory Leydig interneuron in segmental ganglia of the leech Hirudo medicinalis, which modulates specific behaviors in the leech, evokes membrane hyperpolarization directly in the giant glial cell (Schmidt and Deitmer. Eur J Neurosci 11:3125-3133, 1999). We have studied the neuron-to-glia signal transmission in the voltage-clamped giant glial cell to determine whether this interaction exhibits properties of a chemical synapse. The glial response had a mean latency of 4.9 s and was dependent on the action potential frequency; the glial cell responded to as few as five Leydig neuron action potentials in 50% of the trials. The glial current was sustained for minutes during repetitive Leydig neuron activity without any sign of desensitization. The current was sensitive to tetraethylammonium, and its reversal potential of -78 mV shifted with the external K+ concentration. The glial response increased with the duration of the neuronal action potentials and was sensitive to the external Ca2+/Mg2+ concentration ratio. The results suggest that Leydig neuron activity leads to a Ca2+-dependent release of transmitter from the neuronal dendrites, evoking an K+ outward current in the giant glial cell, implying a synapse-like transmission between a neuron and a glial cell.

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Section: Electrophysiologymentioning

confidence: 98%

“…1A). They are electrically and dye-coupled (Keyser et al, 1982) (Fig. 1C), and immunoreactive to a myomodulin-like peptide (Keating and Sahley, 1996).…”

Section: Morphological Relations Between Leydig Cells and Giant Glialmentioning

confidence: 99%

Section: Injection Of Teamentioning

confidence: 99%

Section: Morphological Relationships Between Leydig Neurons and Giantmentioning

confidence: 99%

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Characterization of a synaptiform transmission between a neuron and a glial cell in the leech central nervous system

Britz

Lohr

Schmidt

et al. 2002

Glia

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“…Thus, changes in heart rate can be induced both by inputs from the periphery (Arbas and Calabrese 1984;Davis 1986), as well as through interactions among central circuits and without feedback from the periphery (Arbas and Calabrese 1984). In our search for neural pathways involved in mediating these changes in heart rate, we found several by which accelerations of heart rate could be induced and additionally found the rather paradoxical result that stimulation of a certain group of electrically coupled neurons, the Leydig cells (Nicholls and Baylor 1968;Keyser et al 1982), produced pauses in motor burst production Calabrese 1983, 1984;Calabrese and Arbas 1985).…”

Section: Introductionmentioning

confidence: 81%

Leydig neuron activity modulates heartbeat in the medicinal leech

Arbas

Calabrese

1990

J Comp Physiol A

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1. Leydig neurons fire spontaneously at low rates (less than 4 Hz), but their activity increases with mechanical stimulation or electrical stimulation of mechanosensory neurons. These conditions also cause acceleration of bursting in heart motor neurons. 2. The firing rate of Leydig cells was found to regulate heart rate in chains of isolated ganglia. When Leydig neurons were made to fire action potentials at relatively high frequencies (ca. 5-10 Hz), however, heart motor neurons ceased bursting and were either silenced or fired erratically. 3. Firing of Leydig neurons at high rates caused bilateral heart interneurons of ganglia 3 or 4 to fire tonically rather than in their normal alternating bursts Tonic firing of these heart interneurons accounts for the prolonged barrages of ipsps recorded in heart motor neurons and the disruption of their normal cyclic activity. 4. Preventing spontaneous activity of Leydig neurons with injected currents in isolated ganglia caused deceleration of the heartbeat rhythm but did not halt oscillation. 5. Electrical stimulation of peripheral nerve roots with Leydig neuron activity suppressed in isolated ganglia caused acceleration of heart rate.

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Distribution and morphology of nociceptive cells in the CNS of three species of leeches

Johansen

Hockfield

McKay

1984

J of Comparative Neurology

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The present study describes the segmental variation in the distribution and morphology of nociceptive neurons (N cells) in the central nervous system of the leech. N cells of midbody ganglia can be segregated into lateral and medial types. We show that monoclonal antibodies specific for N cells can distinguish between the two populations. The monoclonal antibodies were used to map the complete distribution of the cells along the nervous cord. There are two pairs of the medial and lateral nociceptive neurons in the midbody ganglia, one pair of the medial type in the sex ganglia (5 and 6), and a pair of the lateral type in ganglia 20 and 21. The caudal brain is without nociceptive neurons. This distribution was confirmed by electrophysiological means. The morphology of N cells in different parts of the nervous system was investigated by intracellular horseradish peroxidase (HRP) injections. In the terminal segmental ganglia the N cells showed extensive arborizations in the head and tail brains and, contrary to N cells in the midbody ganglia, their arborizations spanned more than three segments. N cells are absent in the tail brain, but the N cells of ganglia 20 and 21 were shown to innervate the entire caudal region. The basic morphology of all N-cell homologues was found to be very similar for three leech species. In the sex ganglia the pair of N-cell homologues were examined in Haemopis, Hirudo, and Macrobdella. The results showed a progressive modification in the three species of the cell's morphology, peripheral projections, and physiological responses, possibly correlated with the evolution and complexity of the sexual organs. HRP injections and monoclonal antibody staining revealed that a common feature of N-cell homologues is the presence of processes that tightly surround the cell soma of other cells. This suggests that N cells may have other functional properties in addition to being primary sensory neurons.

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Physiological and anatomical properties of Leydig cells in the segmental nervous system of the leech

Cited by 24 publications

References 16 publications

Characterization of a synaptiform transmission between a neuron and a glial cell in the leech central nervous system

Characterization of a synaptiform transmission between a neuron and a glial cell in the leech central nervous system

Leydig neuron activity modulates heartbeat in the medicinal leech

Distribution and morphology of nociceptive cells in the CNS of three species of leeches

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