Electrophysiological Studies of the Effects of Chronic Administration of Caffeine on the Formation of a Conditioned Defensive Reflex in the Common Snail

Abstract

Chronic administration of caffeine to common snails increased the rate of formation of a conditioned defensive reflex. When daily caffeine injections were given immediately after the training procedure, the conditioned defensive reflex was acquired more quickly than when caffeine injections were given before the training procedure started. Chronic caffeine administration to both trained and untrained snails led to depolarization changes in the membrane potential and reductions in the threshold potential of defensive behavior command neurons in common snails. Comparative studies showed that addition of caffeine to the solution bathing the mollusk nervous system resulted in decreases in the threshold potential of command neurons in both intact and trained snails; there was, however, no change in the membrane resting potential.

The buzz on caffeine in invertebrates: effects on behavior and molecular mechanisms

“…In addition, honey bees given caffeine performed better at visual learning using a delayed-match-to-sample learning paradigm [38]. In the common snail, Helix lucorum , injection of caffeine, either before or after a conditioning trial, increased the number of positive responses (closing of the pneumostoma) to the conditioned stimulus (tapping on the shell) during training such that the rate of acquisition was increased in snails given caffeine [39]. …”

“…One possible explanation is differences in the concentration of caffeine used. The experiments that resulted in a negative effect of caffeine on learning [35, 37, 36] used relatively high concentrations (10 – 50 mM) of caffeine, whereas the studies that showed positive effects on learning [39, 4] used lower concentrations (0.1 to 100 µM). In the visual learning experiments done in honey bees [38], a dose of 100 mM caffeine was given via the use of dimethylformamide to carry the compound across the cuticle, but the proportion of caffeine that actually crossed in to the hemolymph is unknown making it difficult to compare these results.…”

Black tea differs from green tea: it suppresses long-term memory formation inLymnaea

“…In invertebrates, such as bees, caffeine in some situations enhances memory formation [9]; however, in Drosophila caffeine reduces the ability of the flies to form memory on an aversive learning task [10]. Finally, in land snails, a caffeine injection altered the rate of learning [11]. …”

“…It is worth noting, however, that the effects of drinks containing caffeine (e.g. BT and coffee) on memory formation and recall are inconsistent across many studies [7–11]. We will have to perform more experiments on this using different dilutions of BT in the PW.…”

Uso do biofilme perifítico em testes ecotoxicológicos: uma abordagem ecológica da contaminação em reservatórios

“…However, snails are much more sensitive in relation to caffeine contamination. Ferreira et al (2009) found that the LC 50 of caffeine for this group, considering young individuals, is 5 g/L, but Silant'eva et al (2009) pointed out that chronic exposure beginning at 30 mg/kg can cause behavioral and neurological damages in gastropods. Using as example…”