The Effects of Caffeine and Alcohol on the Electrically Evoked Responses of L. terrestris

Regulation on animal research, largely focused on vertebrates, has led to greater expenses for researchers and institutions. Invertebrate animals, however, are rarely included in regulatory oversight, making experimentation comparatively more flexible and inexpensive. Yet, invertebrates are largely overlooked in neurophysiological research, even though the simplicity of invertebrate nervous system models has its advantages. While somatosensory, visual, and auditory evoked potential may be used for pharmacological and toxicological assessment of drugs in both animals and humans, only minor research carried out on invertebrates generally due to the disregard upon comparison between physiological phases or chromosomes of both invertebrates and humans. This study aims to analyze the viability of Lumbricus terrestris, or the common earthworm, as a potential model for electrical somatosensory evoked potential propagation and for drug safety pharmacology assessment. Varying intensities of electrical stimulation potential from 45 ~ 137 mV and accumulative substance injections up to 300 ul were to be used to evaluate telemetric-recorded changes in the evoked potential of the earthworm, and to track the extent of its reproducibility. Alcohol and caffeine, as they are two of the most commonly consumed chemicals in beverages among adolescents, and much was already known about their neurological effects, making the earthworm model’s response to foreign substances evaluable. Numerical changes in latent period, peak point, trough point and wave width of the evoked potential elicited by each substance were analyzed using regression analysis. We found that our peak point and wave width evoked potential parameters were highly indicative of the earthworm’s capability as an evoked potential invertebrate model, especially because responses exhibited expected outcomes of the excitable and inhibitory effects of caffeine and alcohol with high reproducibility.