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Acetylcholinesterase in the development of chick dorsal root ganglia
S Biagioni1, T Odorisio, G Poiana
1Dipartimento di Biologia Cellulare e dello Sviluppo, Universita La Sapienza, Roma, Italy.
Insights
Acetylcholinesterase activity in chick dorsal root ganglia changes during development, with specific activity peaking at day E13 and total enzyme increasing until day E20. The G4 molecular form dominates early release.
Area of Science:
- Neuroscience
- Developmental Biology
- Enzymology
Background:
- Acetylcholinesterase (AChE) expression in chick dorsal root ganglia (DRG) is observed early in development.
- The precise physiological function of AChE in these neurons remains unclear.
- Investigating AChE modifications during development is crucial for understanding its role.
Purpose of the Study:
- To investigate the developmental modifications of acetylcholinesterase in chick dorsal root ganglia.
- To analyze the changes in specific activity and total enzyme levels over time.
- To characterize the molecular forms and release patterns of AChE during development.
Main Methods:
- Measurement of specific acetylcholinesterase activity in chick DRG from embryonic day E5 to E20.
- Quantification of total acetylcholinesterase levels on a per-ganglion basis.
- Analysis of acetylcholinesterase molecular forms (G4 and G2) using biochemical assays.
- Assessment of acetylcholinesterase release from cultured DRG neurons at different developmental stages.
Main Results:
- Specific AChE activity increased from E5 to E13, followed by a decrease.
- Total AChE levels per ganglion showed a continuous rise until E20.
- The G4 molecular form was predominant at E5 (85%), decreasing by E20 to levels similar to G2.
- AChE release from cultured neurons significantly increased by E20, with 90% of the released enzyme being the G4 form.
Conclusions:
- Acetylcholinesterase expression and activity in chick DRG undergo significant developmental changes.
- Both specific activity and total enzyme levels are dynamically regulated throughout embryonic development.
- The predominant G4 molecular form plays a significant role in early development and is notably released by mature neurons.
Abstract:
Acetylcholinesterase is expressed in chick dorsal root ganglia neurons very early in development. Since the physiological role of the enzyme in these cells is still obscure, it appeared of interest to investigate its modifications in the course of development. The specific activity of acetylcholinesterase in chick dorsal root ganglia increases, during in ovo development, from day E5 to day E13; after day E13 there is a decrease. Conversely, when acetylcholinesterase activity was expressed on a per ganglion basis, a continuous increase in the level of the enzyme until day E20 was observed. Acetylcholinesterase is a polymorphic enzyme and its molecular forms have different cellular localizations. Two globular forms, a tetramer (G4) and a dimer (G2), are present in the ganglia, as in chick brain. G4 is the major form at day E5, where it represents about 85% of the activity. This form shows a progressive decrease since day E8, and at day E20 exhibits activity levels similar to those of G2. It is known that acetylcholinesterase-producing cells are also able to release the enzyme in the extracellular space. We determined the release of acetylcholinesterase by cultured dorsal root ganglia neurons at various developmental stages: acetylcholinesterase release is significantly increased at day E20, as compared to younger stages, and 90% of the enzyme released is G4.