Restoration of sensory and motor function in earthworm escape reflex pathways following ventral nerve cord transplantation

Abstract

Twelve segments of earthworm ventral nerve cord (VNC) were excised from either segments 10-22 (i.e., within the MGF sensory field) or segments 75-87 (i.e., within the LGF sensory field) in donor worms and heterotopically, or homotopically, transplanted into recipient animals. Morphological evidence indicated that by four days after transplantation, peripheral connections were formed between the transplanted VNC and the body wall of the recipient, many of these connections involving novel pathways projecting ventrally from the transplant. Restoration of giant fiber touch sensitivity in the transplant occurred from 4-14 days after transplantation. Regardless of the site of transplantation, the restored sensitivity (i.e., MGF versus LGF sensory field) always reflected the origin of the donor VNC. Restoration of MGF-mediated motor activity in the transplant occurred approximately 17-22 days after transplantation. In the case of heterotopic transplants (i.e., anterior VNC into posterior segments), the restored MGF-mediated muscle potentials were facilitating, indicating at least some tendency for persistence of this feature after transplantation. Behavioral observations suggested that reconnections involving other reflex pathways (e.g., those controlling setal movements and peristaltic locomotion) were made within the transplant region and that properties of the restored reflexes reflected those of the donor VNC. The rapid restoration of sensory and motor connections, despite heterotopic placement, indicates a significant capacity for peripheral regeneration by the transplanted VNC. On the other hand, the maintenance of various properties of reflex function, despite heterotopic transplantation, suggests a limited capacity for rearrangement of established central connections in the transplanted VNC.

Influence of ultraviolet radiation on selected physiological responses of earthworms

“…This study reveals striking changes in behavior after UV exposure. It can be inferred that these abnormal behaviors of the earthworm are mediated by the nervous system (Howell, 1939;Mulloney, 1970;Vining and Drewes, 1985;Hassoni et al, 1985). We therefore believe that these earthworms, especially A. gracilis, might be a new model animal suitable for studying the related neurophysiology, such as neuromuscular junction regulation and neurotransmitter release under UV exposure.…”

Influence of ultraviolet radiation on selected physiological responses of earthworms

“…This study reveals striking changes in behavior after UV exposure. It can be inferred that these abnormal behaviors of the earthworm are mediated by the nervous system (Howell, 1939;Mulloney, 1970;Vining and Drewes, 1985;Hassoni et al, 1985). We therefore believe that these earthworms, especially A. gracilis, might be a new model animal suitable for studying the related neurophysiology, such as neuromuscular junction regulation and neurotransmitter release under UV exposure.…”

Annotation of nerve cord transcriptome in earthworm Eisenia fetida

“…Acknowledging the correlation between nerve cord and escape reflex of earthworm, Drewes, 1984 indicated the activation of the giant nerve fibers in the ventral nerve cord is critically required to elicit the escape reflexes in the species under threatening external stimuli [8] . Subsequent studies have confirmed the transplantation of the ventral nerve cord in heterotrophic and homotropic manner has the capability of restoring the sensory and motor activities to reconstruct the crucial behavioral reflex pathways associated with the escape mechanism of the worm [9] .…”

Organization of the sensory system of the earthworm Lumbricus terrestris (Annelida, Clitellata) visualized by DiI

“…The importance of mechanical, chemical, and light perception in annelid skin reflexes and locomotory behavior was recognized by Knapp and Mill (1967). The stimulation of the body surface induces escape and withdrawal reflexes organized by complex neuronal mechanisms (Vining and Drewes,1985).…”

Influence of ultraviolet radiation on selected physiological responses of earthworms

“…This study reveals striking changes in behavior after UV exposure. It can be inferred that these abnormal behaviors of the earthworm are mediated by the nervous system (Howell, 1939;Mulloney, 1970;Vining and Drewes, 1985;Hassoni et al, 1985). We therefore believe that these earthworms, especially A. gracilis, might be a new model animal suitable for studying the related neurophysiology, such as neuromuscular junction regulation and neurotransmitter release under UV exposure.…”

Annotation of nerve cord transcriptome in earthworm Eisenia fetida

“…Acknowledging the correlation between nerve cord and escape reflex of earthworm, Drewes, 1984 indicated the activation of the giant nerve fibers in the ventral nerve cord is critically required to elicit the escape reflexes in the species under threatening external stimuli [8] . Subsequent studies have confirmed the transplantation of the ventral nerve cord in heterotrophic and homotropic manner has the capability of restoring the sensory and motor activities to reconstruct the crucial behavioral reflex pathways associated with the escape mechanism of the worm [9] .…”

Organization of the sensory system of the earthworm Lumbricus terrestris (Annelida, Clitellata) visualized by DiI

“…The importance of mechanical, chemical, and light perception in annelid skin reflexes and locomotory behavior was recognized by Knapp and Mill (1967). The stimulation of the body surface induces escape and withdrawal reflexes organized by complex neuronal mechanisms (Vining and Drewes,1985).…”

Influence of ultraviolet radiation on selected physiological responses of earthworms

“…This study reveals striking changes in behavior after UV exposure. It can be inferred that these abnormal behaviors of the earthworm are mediated by the nervous system (Howell, 1939;Mulloney, 1970;Vining and Drewes, 1985;Hassoni et al, 1985). We therefore believe that these earthworms, especially A. gracilis, might be a new model animal suitable for studying the related neurophysiology, such as neuromuscular junction regulation and neurotransmitter release under UV exposure.…”

Annotation of nerve cord transcriptome in earthworm Eisenia fetida

“…Acknowledging the correlation between nerve cord and escape reflex of earthworm, Drewes, 1984 indicated the activation of the giant nerve fibers in the ventral nerve cord is critically required to elicit the escape reflexes in the species under threatening external stimuli [8] . Subsequent studies have confirmed the transplantation of the ventral nerve cord in heterotrophic and homotropic manner has the capability of restoring the sensory and motor activities to reconstruct the crucial behavioral reflex pathways associated with the escape mechanism of the worm [9] .…”

Organization of the sensory system of the earthworm Lumbricus terrestris (Annelida, Clitellata) visualized by DiI

“…The importance of mechanical, chemical, and light perception in annelid skin reflexes and locomotory behavior was recognized by Knapp and Mill (1967). The stimulation of the body surface induces escape and withdrawal reflexes organized by complex neuronal mechanisms (Vining and Drewes,1985).…”