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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 recovery time is increased with loss of GABAergic transmission, and improved by antiepileptic drugs.In control conditions, wild-type C. elegans take significantly less time to recover from an electric shock when compared to loss-of-function mutations in the GABA biosynthetic enzyme unc-25 or the GABA receptor unc-49. Treatments with 3.0 mM LEV, 1.0 mM RTG and 3.0 mM VPA reduce unc-25 and unc-49 mutant recovery. Error bars represent standard error of the mean and significance was determined using two-way ANOVA and Holm-Sidak multiple comparisons test where ***P≤0.001. ns = not significant P>0.05 and n≥17.
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pone.0163786.g003: Electroshock recovery time is increased with loss of GABAergic transmission, and improved by antiepileptic drugs.In control conditions, wild-type C. elegans take significantly less time to recover from an electric shock when compared to loss-of-function mutations in the GABA biosynthetic enzyme unc-25 or the GABA receptor unc-49. Treatments with 3.0 mM LEV, 1.0 mM RTG and 3.0 mM VPA reduce unc-25 and unc-49 mutant recovery. Error bars represent standard error of the mean and significance was determined using two-way ANOVA and Holm-Sidak multiple comparisons test where ***P≤0.001. ns = not significant P>0.05 and n≥17.

Mentions: C. elegans moves by generating repeated sinusoidal body bends in a given direction. While somewhat of an oversimplification, generally body bends are generated by excitatory cholinergic motor neurons stimulating contraction of body wall muscles on one side of the animal, while inhibitory GABAergic motor neurons trigger relaxation of body wall muscles on the opposing side of the animal [8, 9, 11, 33–37]. To determine how changes in motor neuron function affect recovery time following electric shock, we tested unc-25 mutants, which are unable to synthesize GABA. A strong loss-of-function allele of unc-25, e156 [8], slowed recovery significantly compared to wild-type animals as shown by S2 Video and quantification in Fig 2B. Quantification of recovery time demonstrated that wild-type animals recover in 33.0±4.5 seconds compared to unc-25 mutants which recover in 89.5±105 seconds (Student’s t-test, T(2,73) = -4.681, P<0.001, Fig 2B). Loss of function in unc-49, the GABAA receptor on muscles, also delayed recovery (Fig 3). These results indicate that loss of inhibitory GABAergic transmission at the neuromuscular junction leads to increased sensitivity to electric shock.


Modulating Behavior in C . elegans Using Electroshock and Antiepileptic Drugs
Electroshock recovery time is increased with loss of GABAergic transmission, and improved by antiepileptic drugs.In control conditions, wild-type C. elegans take significantly less time to recover from an electric shock when compared to loss-of-function mutations in the GABA biosynthetic enzyme unc-25 or the GABA receptor unc-49. Treatments with 3.0 mM LEV, 1.0 mM RTG and 3.0 mM VPA reduce unc-25 and unc-49 mutant recovery. Error bars represent standard error of the mean and significance was determined using two-way ANOVA and Holm-Sidak multiple comparisons test where ***P≤0.001. ns = not significant P>0.05 and n≥17.
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Related In: Results  -  Collection

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pone.0163786.g003: Electroshock recovery time is increased with loss of GABAergic transmission, and improved by antiepileptic drugs.In control conditions, wild-type C. elegans take significantly less time to recover from an electric shock when compared to loss-of-function mutations in the GABA biosynthetic enzyme unc-25 or the GABA receptor unc-49. Treatments with 3.0 mM LEV, 1.0 mM RTG and 3.0 mM VPA reduce unc-25 and unc-49 mutant recovery. Error bars represent standard error of the mean and significance was determined using two-way ANOVA and Holm-Sidak multiple comparisons test where ***P≤0.001. ns = not significant P>0.05 and n≥17.
Mentions: C. elegans moves by generating repeated sinusoidal body bends in a given direction. While somewhat of an oversimplification, generally body bends are generated by excitatory cholinergic motor neurons stimulating contraction of body wall muscles on one side of the animal, while inhibitory GABAergic motor neurons trigger relaxation of body wall muscles on the opposing side of the animal [8, 9, 11, 33–37]. To determine how changes in motor neuron function affect recovery time following electric shock, we tested unc-25 mutants, which are unable to synthesize GABA. A strong loss-of-function allele of unc-25, e156 [8], slowed recovery significantly compared to wild-type animals as shown by S2 Video and quantification in Fig 2B. Quantification of recovery time demonstrated that wild-type animals recover in 33.0±4.5 seconds compared to unc-25 mutants which recover in 89.5±105 seconds (Student’s t-test, T(2,73) = -4.681, P<0.001, Fig 2B). Loss of function in unc-49, the GABAA receptor on muscles, also delayed recovery (Fig 3). These results indicate that loss of inhibitory GABAergic transmission at the neuromuscular junction leads to increased sensitivity 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