WASTED

Worm Alcohol Studies to Examine Drug Tolerance (WASTED) is a research project within SWIRL which is investigating the effects of ethanol on Lumbriculus variegatus. Ethanol produces dose-dependent motor impairment in man and other animals, including rodents, Drosophila, and C. elegans (Wallace et al., 2007). Ethanol is known to potentiate the GABAergic effects in the central nervous system of higher organisms (Davies, 2003) and to date, we have demonstrated that L. variegatus displays time and concentration-dependent effects when exposed to ethanol (Mathur et al., 2021) without the development of ethanol tolerance (Mahmood et al., 2022).  

WASTED aims to examine the behavioural effects of ethanol in L. variegatus and why this species does not develop ethanol tolerance, as well as investigate the presence or absence of GABAergic signalling in this species.  

Below is an abstract which highlights some of our current work within WASTED

The effects of acute and chronic ethanol exposure in the novel in vivo research organism, Lumbriculus variegatus

Romessa Mahmood, Elis Roome, Kwang Lee & Aidan Seeley

Swansea Worm Integrative Research Laboratory

Swansea University Medical School

Swansea University 

Introduction 

Ethanol produces dose-dependent motor impairment in man and in other animals, including rodents, Drosophila, and C. elegans [1]. Previously, we have demonstrated that Lumbriculus variegatus, a species of aquatic worm, demonstrates concentration-dependent behavioural changes when exposed to ethanol [2]. 

Here we demonstrate that ethanol produces rapid inhibition of L. variegatus free, unstimulated, locomotor activity and that acute and chronic exposure to ethanol does not affect these behavioural changes but does result in significant changes to L. variegatus body size. 

Method 

Unstimulated free locomotion was measured following exposure to ethanol (0-500 mM) by rapid image collection of L. variegatus. The effect of repeated acute exposure to ethanol was tested by exposing L. variegatus to 500 mM ethanol three times at 10 minutes intervals spaced 30 minutes apart and collecting images. The effects of ethanol (0-500 mM) on locomotion were also observed in ethanol naïve L. variegatus or L. variegatus exposed to 100 mM ethanol for ≥21 days. L. variegatus size was determined by ImageJ analysis following the acquisition of a single image of individual worms. Statistical significance was determined by paired t-tests or a two-way ANOVA. 

Results

After two minutes of exposure to ethanol, L. variegatus free locomotion was significantly inhibited free locomotion by 35.6±6.5% at 250 mM (p=.02, n=11) and 33.1±8.7% at 500 mM (p=.03, n=11). These effects plateaued after four minutes of exposure to 250 mM (p=.003, n=11) and 500 mM ethanol (p=.002, n=11). Repeated acute exposure to 500 mM resulted in a significant decrease in L. variegatus free locomotion (p<.0001, n=12) but there was no significant difference to L. variegatus movement between exposures (p>.05, n=12).

Following exposure to 100 mM ethanol continuously for ≥21 days, chronically exposed L. variegatus demonstrated no significant difference in response to ethanol (0-500 mM) compared to ethanol naïve L. variegatus (p>.05, n=9). However, a significant size increase was observed in chronically exposed L. variegatus compared to their ethanol naïve counterparts (p<.01, n=6). 

Conclusions 

This work demonstrates the concentration-dependent effects of ethanol on L. variegatus behaviour, and that ethanol tolerance is not induced in this mode, which highlights the wider potential utility of L. variegatus for ethanol research. 

References

1. Wallace, M.J. et al. (2007) Acute Functional Tolerance to Ethanol Mediated by Protein Kinase Cε. NPP; 32: 127-136. DOI: 10.1038/sj.npp.1301059

2. Mathur, S.N. et al. (2021) Concentration-dependent behavioural effects of ethanol in the novel in vivo model, Lumbriculus variegatus. Br. J. Pharmacol. 178:4923–5006. DOI:10.111/bph.15648.