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Inhibition of feeding responses by the molluscicide, metaldehyde
C R McCrohan1, J D Mills, S C Cheng
1School of Biological Sciences, University of Manchester, U.K.
Abstract:
Metaldehyde, applied to the lips, inhibits spontaneous biting movements and disrupts rhythmic feeding motor output. Applied directly to the CNS, it induces a region of negetive slope conductance in the steady-state I-V curve, which could contribute towards generation of convulsant activity. Isolated muscle tissue (buccal mess, gut and foot) shows increased frequency and amplitude of contractions when exposed to metaldehyde. All these actions contribute towards the disruption of feeding behaviour.
Insights
Metaldehyde disrupts feeding behavior by inhibiting biting and motor output when applied to the lips. It also causes convulsions and increases muscle contractions when applied to the central nervous system (CNS) and muscle tissue.
Area of Science:
- Neuroscience
- Molluscan Physiology
- Pesticide Toxicology
Background:
- Metaldehyde is a common molluscicide.
- Its precise mechanisms of action on feeding behavior and neuromuscular function are not fully understood.
Purpose of the Study:
- To investigate the neurophysiological and behavioral effects of metaldehyde.
- To elucidate the impact of metaldehyde on feeding motor output and muscle activity.
Main Methods:
- Application of metaldehyde to the lips of organisms to observe effects on biting and feeding.
- Direct application of metaldehyde to the central nervous system (CNS) to analyze electrophysiological properties.
- Exposure of isolated muscle tissues (buccal mass, gut, foot) to metaldehyde to assess contractile responses.
Main Results:
- Metaldehyde applied to lips inhibited spontaneous biting and disrupted rhythmic feeding motor output.
- Direct CNS application induced negative slope conductance, potentially causing convulsions.
- Isolated muscle tissues exhibited increased contraction frequency and amplitude upon metaldehyde exposure.
Conclusions:
- Metaldehyde disrupts normal feeding behavior through multiple mechanisms.
- Neurotoxic and direct muscle-stimulating effects of metaldehyde contribute to its overall impact on mollusc function.