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Modulating Behavior in C . elegans Using Electroshock and Antiepileptic Drugs

View Article: PubMed Central - PubMed

ABSTRACT

The microscopic nematode Caenorhabditis elegans has emerged as a valuable model for understanding the molecular and cellular basis of neurological disorders. The worm offers important physiological similarities to mammalian models such as conserved neuron morphology, ion channels, and neurotransmitters. While a wide-array of behavioral assays are available in C. elegans, an assay for electroshock/electroconvulsion remains absent. Here, we have developed a quantitative behavioral method to assess the locomotor response following electric shock in C. elegans. Electric shock impairs normal locomotion, and induces paralysis and muscle twitching; after a brief recovery period, shocked animals resume normal locomotion. We tested electric shock responses in loss-of-function mutants for unc-25, which encodes the GABA biosynthetic enzyme GAD, and unc-49, which encodes the GABAA receptor. unc-25 and unc-49 mutants have decreased inhibitory GABAergic transmission to muscles, and take significantly more time to recover normal locomotion following electric shock compared to wild-type. Importantly, increased sensitivity of unc-25 and unc-49 mutants to electric shock is rescued by treatment with antiepileptic drugs, such as retigabine. Additionally, we show that pentylenetetrazol (PTZ), a GABAA receptor antagonist and proconvulsant in mammalian and C. elegans seizure models, increases susceptibility of worms to electric shock.

No MeSH data available.


Related in: MedlinePlus

Electroshock results in paralysis and recovery of C. elegans.(A) Freeze-frame image of a wild-type C. elegans inside an experimental tube. The images are still frames from a video of the raw data seen in S1 Video and are taken before, during, and after the electric shock (47V, 3 sec). Before the shock, the animal moves in a sinusoidal wave pattern. After the shock, the animal recovers locomotion within ~30 seconds. The recovered worm is represented with an asterisk. (B) Quantification of the visual in (A) depicts the mean recovery time of wild-type (33.0±4.5 seconds), which are compared to unc-25 mutants (89.5±10.5 seconds). Error bars represent standard error of the mean and significance was determined using Student’s t-test where ***P≤0.001 and n≥35.
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pone.0163786.g002: Electroshock results in paralysis and recovery of C. elegans.(A) Freeze-frame image of a wild-type C. elegans inside an experimental tube. The images are still frames from a video of the raw data seen in S1 Video and are taken before, during, and after the electric shock (47V, 3 sec). Before the shock, the animal moves in a sinusoidal wave pattern. After the shock, the animal recovers locomotion within ~30 seconds. The recovered worm is represented with an asterisk. (B) Quantification of the visual in (A) depicts the mean recovery time of wild-type (33.0±4.5 seconds), which are compared to unc-25 mutants (89.5±10.5 seconds). Error bars represent standard error of the mean and significance was determined using Student’s t-test where ***P≤0.001 and n≥35.

Mentions: We set out to develop a model of seizure in C. elegans using electric shock to induce convulsions similar to practices in other systems [24, 25]. To begin, worms were placed in a transparent plastic tube containing M9 saline solution (Fig 1). Both ends of the tube were plugged with copper wire and connected to a square-pulse generating stimulator. The voltage was chosen based on a voltage-response curve with wild-type worms where average recovery time at 47V is approximately half that of the recovery time at 60V (maximum voltage with recovery; S1 Fig). This method allowed us to assess approximately ten worms per experiment by recording animals with a camera. During a brief electric shock application for 3 seconds, worms display paralysis and elongation (S1 Video, Fig 2A). This is immediately followed by slow unilateral body-bends and convulsions. We define convulsions as repeated unilateral body bends with muscle twitching. With removal of electric shock, convulsions were followed by rapid recovery in which most animals resume sinusoidal, swimming movement (S1 Video). For all experiments, animals were habituated in M9 solution for 30 minutes prior to electric shock.


Modulating Behavior in C . elegans Using Electroshock and Antiepileptic Drugs
Electroshock results in paralysis and recovery of C. elegans.(A) Freeze-frame image of a wild-type C. elegans inside an experimental tube. The images are still frames from a video of the raw data seen in S1 Video and are taken before, during, and after the electric shock (47V, 3 sec). Before the shock, the animal moves in a sinusoidal wave pattern. After the shock, the animal recovers locomotion within ~30 seconds. The recovered worm is represented with an asterisk. (B) Quantification of the visual in (A) depicts the mean recovery time of wild-type (33.0±4.5 seconds), which are compared to unc-25 mutants (89.5±10.5 seconds). Error bars represent standard error of the mean and significance was determined using Student’s t-test where ***P≤0.001 and n≥35.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036823&req=5

pone.0163786.g002: Electroshock results in paralysis and recovery of C. elegans.(A) Freeze-frame image of a wild-type C. elegans inside an experimental tube. The images are still frames from a video of the raw data seen in S1 Video and are taken before, during, and after the electric shock (47V, 3 sec). Before the shock, the animal moves in a sinusoidal wave pattern. After the shock, the animal recovers locomotion within ~30 seconds. The recovered worm is represented with an asterisk. (B) Quantification of the visual in (A) depicts the mean recovery time of wild-type (33.0±4.5 seconds), which are compared to unc-25 mutants (89.5±10.5 seconds). Error bars represent standard error of the mean and significance was determined using Student’s t-test where ***P≤0.001 and n≥35.
Mentions: We set out to develop a model of seizure in C. elegans using electric shock to induce convulsions similar to practices in other systems [24, 25]. To begin, worms were placed in a transparent plastic tube containing M9 saline solution (Fig 1). Both ends of the tube were plugged with copper wire and connected to a square-pulse generating stimulator. The voltage was chosen based on a voltage-response curve with wild-type worms where average recovery time at 47V is approximately half that of the recovery time at 60V (maximum voltage with recovery; S1 Fig). This method allowed us to assess approximately ten worms per experiment by recording animals with a camera. During a brief electric shock application for 3 seconds, worms display paralysis and elongation (S1 Video, Fig 2A). This is immediately followed by slow unilateral body-bends and convulsions. We define convulsions as repeated unilateral body bends with muscle twitching. With removal of electric shock, convulsions were followed by rapid recovery in which most animals resume sinusoidal, swimming movement (S1 Video). For all experiments, animals were habituated in M9 solution for 30 minutes prior to electric shock.

View Article: PubMed Central - PubMed

ABSTRACT

The microscopic nematode Caenorhabditis elegans has emerged as a valuable model for understanding the molecular and cellular basis of neurological disorders. The worm offers important physiological similarities to mammalian models such as conserved neuron morphology, ion channels, and neurotransmitters. While a wide-array of behavioral assays are available in C. elegans, an assay for electroshock/electroconvulsion remains absent. Here, we have developed a quantitative behavioral method to assess the locomotor response following electric shock in C. elegans. Electric shock impairs normal locomotion, and induces paralysis and muscle twitching; after a brief recovery period, shocked animals resume normal locomotion. We tested electric shock responses in loss-of-function mutants for unc-25, which encodes the GABA biosynthetic enzyme GAD, and unc-49, which encodes the GABAA receptor. unc-25 and unc-49 mutants have decreased inhibitory GABAergic transmission to muscles, and take significantly more time to recover normal locomotion following electric shock compared to wild-type. Importantly, increased sensitivity of unc-25 and unc-49 mutants to electric shock is rescued by treatment with antiepileptic drugs, such as retigabine. Additionally, we show that pentylenetetrazol (PTZ), a GABAA receptor antagonist and proconvulsant in mammalian and C. elegans seizure models, increases susceptibility of worms to electric shock.

No MeSH data available.


Related in: MedlinePlus