Caenorhabditis elegans (C. elegans) is a widely used model organism in neuroscience studies, particularly those involving neurotransmitters. Several studies have examined various aspects of neurotransmitter systems using this organism. Here are some key points:

• Dopamine: C. elegans has been extensively studied for dopamine signaling, which is involved in movement and behavior control. Studies have utilized this organism to understand dopamine-related disorders and revealed insights into how dopamine affects locomotion and sensory behaviors.

• Serotonin: Research in C. elegans has provided significant insights into serotonin's role in modulating various behaviors, including feeding, egg-laying, and fat storage. These studies help elucidate the broader roles of serotonin in the nervous system.

• Acetylcholine: C. elegans has been a key model in studying cholinergic signaling, primarily because acetylcholine is the primary excitatory neurotransmitter in the nematode's nervous system.

• GABA (Gamma-Aminobutyric Acid): Studies in C. elegans have explored GABAergic signaling, which is crucial for inhibitory motor neurotransmission and plays a vital role in muscle relaxation during locomotion.

• Glutamate: C. elegans has also been employed to study glutamate signaling. Research has provided insights into how glutamate receptors operate and their role in various neural circuits.

These studies often leverage the genetic tractability and simplicity of the C. elegans nervous system, making it advantageous for decoding complex neurotransmitter networks. While these points summarize frequently conducted neurotransmitter research in C. elegans, specific studies or articles may vary.

For more detailed and specific examples, references like the WormBook or databases like PubMed can be useful for finding specific papers and reviews.