The inhibitory effect of nicotine on Lumbriculus variegatus stereotypical movements and locomotor activity.

Nicotine has been shown to induce profound physiological and behavioural responses in invertebrate model organisms such as Caenorhabditis elegans and Drosophila melanogaster. Lumbriculus variegatus is an aquatic oligochaete worm which we have previously demonstrated has application within pharmacological research. Herein, we demonstrate the presence of endogenous acetylcholine and cholinesterase activity within L. variegatus and show the time-dependent effects on the sensitivity of L. variegatus to nicotine. We describe the effects of a broad range of concentrations of nicotine (1 μM - 1 mM) on L. variegatus response to tactile stimulation and locomotor activity following acute (10-min) and chronic (24-h) exposure. Here, we show that 10 min of exposure to ≥0.1 mM nicotine reversibly reduces the ability of tactile stimulation to elicit stereotypical movements of body reversal and helical swimming, and locomotor activity in L. variegatus. We also demonstrate that exposure to ≥0.1 mM nicotine for 24 h was toxic to L. variegatus. Chronic low-dose nicotine ≥25 μM similarly inhibits L. variegatus behaviours with 50 μM causing irreversible inhibition of movement. Thus, L. variegatus presents a model for studying the effects of nicotine and further demonstrates the application of the in vivo model L. variegatus for behavioural pharmacology research.