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Growth-associated protein (GAP-43) in terminal Schwann cells of rat Pacinian corpuscles
1Department of Anatomy, School of Medicine, Brno, Czech Republic.
Insights
Growth-associated protein (GAP-43) is present in immature and denervated Pacinian corpuscles. Extra-axonal cues, not just axons, regulate GAP-43, suggesting a role in Schwann cell development.
Area of Science:
- Neuroscience
- Cell Biology
- Developmental Biology
Background:
- Growth-associated protein (GAP-43) is crucial for neuronal development and plasticity.
- Pacinian corpuscles are mechanoreceptors involved in touch and vibration sensation.
- Understanding GAP-43 regulation in sensory structures is key to neural repair.
Purpose of the Study:
- To investigate the expression and regulation of GAP-43 in Pacinian corpuscles during development and after nerve injury.
- To determine the role of extra-axonal factors in GAP-43 modulation within these sensory structures.
Main Methods:
- Immunohistochemical analysis of GAP-43 in Pacinian corpuscles from neonatal and adult rats.
- Examination of GAP-43 expression following experimental denervation and reinnervation of adult rat Pacinian corpuscles.
Main Results:
- Immature Pacinian corpuscles consistently showed GAP-43 immunoreactivity in their inner cores.
- Mature corpuscles had reduced GAP-43 expression, which significantly increased after denervation.
- Reinnervation partially reduced GAP-43 expression, but a notable percentage remained positive, indicating extra-axonal influence.
Conclusions:
- GAP-43 regulation in Pacinian corpuscles involves both axonal and extra-axonal signals.
- Terminal Schwann cells likely play a role in modulating GAP-43 expression during nerve regeneration and structure formation.
Abstract:
Growth-associated protein (GAP-43) immunoreactivity was examined in Pacinian corpuscles of intact neonatal and adult rats as well as after denervation and reinnervation in adult rats. All immature Pacinian corpuscles were GAP-43 immunoreactive (GAP-43+) in their inner cores while only 46 +/- 5.6% of the mature corpuscles exhibited GAP-43+ inner cores. The frequency of GAP-43+ inner cores increased to 90 +/- 7.2% after their permanent denervation. The expression of GAP-43 in the inner cores was reduced by contact with regrowing axons, but 38 +/- 5.3% of Pacinian corpuscles retained GAP-43+ in their inner cores following reinnervation. These results indicate that GAP-43 regulation is not confined only to axons but also involves some extra-axonal cues, and support a role for this protein in the process formation by terminal Schwann cells.