Evolutional study on acetylcholine expression

Area of Science:

• Biochemistry
• Molecular Biology
• Evolutionary Biology

Background:

• Acetylcholine (ACh) is a known neurotransmitter in vertebrate and insect nervous systems.
• Evidence for ACh in lower invertebrates, plants, and fungi has been indirect.
• Non-neuronal ACh has been recently discovered in mammals.

Purpose of the Study:

• To investigate the presence and synthesis of Acetylcholine (ACh) in a wide range of organisms.
• To identify the synthetic enzymes involved in ACh production, specifically choline acetyltransferase (ChAT) and carnitine acetyltransferase (CarAT).
• To understand the evolutionary origins and potential functions of ACh.

Main Methods:

• Assayed ACh content and synthesis in various invertebrates, plants, fungi, and bacteria.
• Focused on the presence and activity of ChAT and CarAT enzymes.
• Utilized a specific radioimmunoassay to detect ACh and enzyme inhibitor sensitivity.

Main Results:

• Acetylcholine (ACh) was detected in all tested organisms, with levels varying significantly.
• ACh synthesis was confirmed in all samples, with activity sensitive to ChAT and CarAT inhibitors in many animal, plant, and fungal samples.
• Lower ACh synthesis levels, insensitive to inhibitors, were observed in some plants, fungi, and bacteria.

Conclusions:

• Acetylcholine (ACh) and ACh-synthesizing activity are present in evolutionarily primitive and complex multicellular organisms.
• These findings suggest ACh has been expressed since the early stages of life.
• ACh likely functions as both a local mediator and a neurotransmitter across diverse species.