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Intrinsic properties of larval zebrafish neurons in ethanol.

Ikeda H, Delargy AH, Yokogawa T, Urban JM, Burgess HA, Ono F - PLoS ONE (2013)

Bottom Line: The behavioral effects of ethanol have been studied in multiple animal models including zebrafish.The intracellular [Ca(2+)] response in MiD3 neurons decreased in 100 mM ethanol, while Mauthner neurons and vestibulospinal neurons required >300 mM ethanol to elicit similar effects.The ethanol effect in Mauthner neurons was reversible following removal of ethanol.

View Article: PubMed Central - PubMed

Affiliation: Section on Model Synaptic Systems, Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland, United States of America.

ABSTRACT
The behavioral effects of ethanol have been studied in multiple animal models including zebrafish. Locomotion of zebrafish larvae is resistant to high concentrations of ethanol in bath solution. This resistance has been attributed to a lower systemic concentration of ethanol in zebrafish when compared with bath solution, although the mechanism to maintain such a steep gradient is unclear. Here we examined whether the intrinsic properties of neurons play roles in this resistance. In order to minimize the contribution of metabolism and diffusional barriers, larvae were hemisected and the anterior half immersed in a range of ethanol concentrations thereby ensuring the free access of bath ethanol to the brain. The response to vibrational stimuli of three types of reticulospinal neurons: Mauthner neurons, vestibulospinal neurons, and MiD3 neurons were examined using an intracellular calcium indicator. The intracellular [Ca(2+)] response in MiD3 neurons decreased in 100 mM ethanol, while Mauthner neurons and vestibulospinal neurons required >300 mM ethanol to elicit similar effects. The ethanol effect in Mauthner neurons was reversible following removal of ethanol. Interestingly, activities of MiD3 neurons displayed spontaneous recovery in 300 mM ethanol, suggestive of acute tolerance. Finally, we examined with mechanical vibration the startle response of free-swimming larvae in 300 mM ethanol. Ethanol treatment abolished long latency startle responses, suggesting a functional change in neural processing. These data support the hypothesis that individual neurons in larval zebrafish brains have distinct patterns of response to ethanol dictated by specific molecular targets.

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The effects of ethanol on acoustic startle responses.Histograms showing the latency distribution of startle responses of free-swimming larvae after 1 hr exposure to 0 (A) and 300 mM ethanol (B). N in parenthesis is the number of responses analyzed (from a total of 100–120 larvae each). Percentage of larvae showing responses with latencies <15 ms (C) and >15 ms (D) after exposure to 0, 30, 100 and 300 mM ethanol. (* P<0.001 t-test compared to 0 mM group). N = 4 groups of 20 larvae (0, 30, 100 mM treatments) or 8 groups of 20 larvae (300 mM treatment).
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pone-0063318-g005: The effects of ethanol on acoustic startle responses.Histograms showing the latency distribution of startle responses of free-swimming larvae after 1 hr exposure to 0 (A) and 300 mM ethanol (B). N in parenthesis is the number of responses analyzed (from a total of 100–120 larvae each). Percentage of larvae showing responses with latencies <15 ms (C) and >15 ms (D) after exposure to 0, 30, 100 and 300 mM ethanol. (* P<0.001 t-test compared to 0 mM group). N = 4 groups of 20 larvae (0, 30, 100 mM treatments) or 8 groups of 20 larvae (300 mM treatment).

Mentions: Reticulospinal neurons including Mauthner neurons and MiD3 neurons are activated in startle responses [14]. We therefore examined whether the ethanol-induced changes in reticulospinal neuron activity affect acoustic startle responsiveness. After 1 hr treatment in 0, 30, 100 and 300 mM ethanol, larvae were tested with mechanical vibration while monitoring startle responses. Reponses were identified based on kinematic parameters matching C-starts [13]. As previously described, two types of startle responses were observed in untreated larvae, distinguished by latency, one centering around 7–8 ms (short latency C-start, ‘SLC’) and the other centering around 28 ms (long latency C-start, ‘LLC’) (Fig. 5A) [13]. 300 mM ethanol treatment did not affect SLC responsiveness (F[3], [16] = 1.4, p = 0.29), but selectively reduced LLC responsiveness (F[3], [16] = 26.6, p<0.001). While the 30 mM and 100 mM ethanol treatments did not produce differences (Fig. 5C, D), in 300 mM treated larvae LLC responses were greatly diminished (Fig. 5B, D). Differential sensitivity of reticulospinal neurons to ethanol likely contributes to the behavioral shift seen in 300 mM ethanol.


Intrinsic properties of larval zebrafish neurons in ethanol.

Ikeda H, Delargy AH, Yokogawa T, Urban JM, Burgess HA, Ono F - PLoS ONE (2013)

The effects of ethanol on acoustic startle responses.Histograms showing the latency distribution of startle responses of free-swimming larvae after 1 hr exposure to 0 (A) and 300 mM ethanol (B). N in parenthesis is the number of responses analyzed (from a total of 100–120 larvae each). Percentage of larvae showing responses with latencies <15 ms (C) and >15 ms (D) after exposure to 0, 30, 100 and 300 mM ethanol. (* P<0.001 t-test compared to 0 mM group). N = 4 groups of 20 larvae (0, 30, 100 mM treatments) or 8 groups of 20 larvae (300 mM treatment).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643919&req=5

pone-0063318-g005: The effects of ethanol on acoustic startle responses.Histograms showing the latency distribution of startle responses of free-swimming larvae after 1 hr exposure to 0 (A) and 300 mM ethanol (B). N in parenthesis is the number of responses analyzed (from a total of 100–120 larvae each). Percentage of larvae showing responses with latencies <15 ms (C) and >15 ms (D) after exposure to 0, 30, 100 and 300 mM ethanol. (* P<0.001 t-test compared to 0 mM group). N = 4 groups of 20 larvae (0, 30, 100 mM treatments) or 8 groups of 20 larvae (300 mM treatment).
Mentions: Reticulospinal neurons including Mauthner neurons and MiD3 neurons are activated in startle responses [14]. We therefore examined whether the ethanol-induced changes in reticulospinal neuron activity affect acoustic startle responsiveness. After 1 hr treatment in 0, 30, 100 and 300 mM ethanol, larvae were tested with mechanical vibration while monitoring startle responses. Reponses were identified based on kinematic parameters matching C-starts [13]. As previously described, two types of startle responses were observed in untreated larvae, distinguished by latency, one centering around 7–8 ms (short latency C-start, ‘SLC’) and the other centering around 28 ms (long latency C-start, ‘LLC’) (Fig. 5A) [13]. 300 mM ethanol treatment did not affect SLC responsiveness (F[3], [16] = 1.4, p = 0.29), but selectively reduced LLC responsiveness (F[3], [16] = 26.6, p<0.001). While the 30 mM and 100 mM ethanol treatments did not produce differences (Fig. 5C, D), in 300 mM treated larvae LLC responses were greatly diminished (Fig. 5B, D). Differential sensitivity of reticulospinal neurons to ethanol likely contributes to the behavioral shift seen in 300 mM ethanol.

Bottom Line: The behavioral effects of ethanol have been studied in multiple animal models including zebrafish.The intracellular [Ca(2+)] response in MiD3 neurons decreased in 100 mM ethanol, while Mauthner neurons and vestibulospinal neurons required >300 mM ethanol to elicit similar effects.The ethanol effect in Mauthner neurons was reversible following removal of ethanol.

View Article: PubMed Central - PubMed

Affiliation: Section on Model Synaptic Systems, Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland, United States of America.

ABSTRACT
The behavioral effects of ethanol have been studied in multiple animal models including zebrafish. Locomotion of zebrafish larvae is resistant to high concentrations of ethanol in bath solution. This resistance has been attributed to a lower systemic concentration of ethanol in zebrafish when compared with bath solution, although the mechanism to maintain such a steep gradient is unclear. Here we examined whether the intrinsic properties of neurons play roles in this resistance. In order to minimize the contribution of metabolism and diffusional barriers, larvae were hemisected and the anterior half immersed in a range of ethanol concentrations thereby ensuring the free access of bath ethanol to the brain. The response to vibrational stimuli of three types of reticulospinal neurons: Mauthner neurons, vestibulospinal neurons, and MiD3 neurons were examined using an intracellular calcium indicator. The intracellular [Ca(2+)] response in MiD3 neurons decreased in 100 mM ethanol, while Mauthner neurons and vestibulospinal neurons required >300 mM ethanol to elicit similar effects. The ethanol effect in Mauthner neurons was reversible following removal of ethanol. Interestingly, activities of MiD3 neurons displayed spontaneous recovery in 300 mM ethanol, suggestive of acute tolerance. Finally, we examined with mechanical vibration the startle response of free-swimming larvae in 300 mM ethanol. Ethanol treatment abolished long latency startle responses, suggesting a functional change in neural processing. These data support the hypothesis that individual neurons in larval zebrafish brains have distinct patterns of response to ethanol dictated by specific molecular targets.

Show MeSH
Related in: MedlinePlus