Prior social experience affects the behavioral and neural responses to acute alcohol in juvenile crayfish

Abstract

The effects of alcohol on society can be devastating, both as an immediate consequence of acute intoxication and as a powerful drug of abuse. However, the neurocellular mechanisms of alcohol intoxication are still elusive, partly because of the complex interactions between alcohol and nervous system function. We found that juvenile crayfish are behaviorally sensitive to acute alcohol exposure and progress through stages that are strikingly similar to those of most other intoxicated organisms. Most surprisingly, we found that the social history of the animals significantly modified the acute effects of alcohol. Crayfish taken from a rich social environment became intoxicated more rapidly than animals that were socially isolated before alcohol exposure. In addition, we found that the modulation of intoxicated behaviors by prior social experience was paralleled on the level of individual neurons. These results significantly improve our understanding of the mechanisms underlying the interplay between social experience, alcohol intoxication and nervous system function.

Effects of Ethanol on Sensory Inputs to the Medial Giant Interneurons of Crayfish

“…Since our previous work had shown that the crayfish LG neurons become modestly sensitized after repeated sensory stimulation in normal crayfish saline ( Swierzbinski et al, 2017 ), we first tested the effect of repeated stimulation on MG neuron excitability. After 10 min of baseline recordings, preparations ( N = 5; 3.6 ± 0.16 cm) were perfused for 90 min with fresh crayfish saline and the antenna II nerve was stimulated every 90 s. We observed minor fluctuations in PSP amplitudes in both early and late PSP components throughout this time period ( Figure 2B ).…”

“…Previous results from our lab demonstrated that juvenile crayfish are behaviorally and physiologically sensitive to EtOH and that this sensitivity is affected by recent social experience ( Swierzbinski et al, 2017 ). When placed in a water-filled tank that contained various concentrations of EtOH, crayfish became more intoxicated over time in a dose-dependent manner, and they progressed through distinct stages of behavioral change.…”

“…Animals were purchased from Atchafalaya Biological and housed in large communal tanks (76 cm × 30 cm × 30 cm, L:W:H) with 50–100 crayfish until social isolation. Since social experience significantly affects alcohol sensitivity in crayfish, both behaviorally and physiologically ( Swierzbinski et al, 2017 ), we decided to use only pre-isolated animals for the current study. All animals were socially isolated for 7–10 days in small individual tanks (15 cm × 8 cm × 10 cm, L:W:H) prior to the experiments.…”

“…Previously, repeated stimulation of the LG while superfused with normal crayfish saline produced weak sensitization in some preparations ( Swierzbinski et al, 2017 ). To measure how MG PSPs are affected during long-term repeated stimulations while superfused with normal crayfish, preparations were exposed to a 10 min saline baseline followed by 90 min of normal crayfish saline.…”

“…Across invertebrate studies, the symptoms of ethanol (EtOH) intoxication are highly conserved. This includes research performed in nematodes ( Topper et al, 2014 ), fruit flies ( Lee et al, 2008 ), and crayfish ( Friedman et al, 1988 ; Macmillan et al, 1991 ; Blundon and Bittner, 1992 ; Swierzbinski et al, 2017 ). Similar to vertebrates, lower doses produce disinhibition while higher doses produce increased incoordination and/or decreased activity.…”