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Dopamine elicits feeding motor program in Limax maximus.
Summary
Dopamine triggers the feeding motor program (FMP) in the mollusc Limax maximus. This neurotransmitter excites motor neurons and its effects resemble vertebrate D1 receptors, suggesting a key role in feeding behavior.
Area of Science:
- Neuroscience
- Animal Behavior
- Biochemistry
Background:
- The terrestrial mollusc Limax maximus exhibits a feeding motor program (FMP) in response to lip chemostimulation.
- Neural control of FMP involves neurotransmitters within the cerebral and buccal ganglia.
Purpose of the Study:
- To identify neurotransmitters controlling the expression of the feeding motor program (FMP) in Limax maximus.
- To characterize the role of dopamine in the neural circuitry of feeding behavior.
Main Methods:
- Chemical analysis of neurotransmitter concentrations in Limax maximus ganglia.
- In vitro application of exogenous dopamine and other agonists/antagonists to ganglia.
- Electrophysiological recording of neuronal activity and motor program output.
Main Results:
- Dopamine was detected in Limax cerebral and buccal ganglia, with higher concentrations in the cerebral ganglia.
- Exogenous dopamine application modulated specific neurons (FB excitation, BSN inhibition) and triggered FMP output in a dose-dependent manner.
- The Limax dopamine system showed agonist similarities to vertebrate D1 receptors but distinct antagonist properties; serotonin had different effects.
Conclusions:
- Dopamine acts as a key neurotransmitter in the Limax maximus feeding motor program (FMP).
- Dopamine likely functions as an endogenous transmitter for triggering and sustaining feeding behavior in this mollusc.