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Development of dynorphin-like immunoreactive auditory nerve terminals in the chick
1Dept. of Biology, Texas Woman's University, Denton 76204-5799, USA. f-code@venus.twu.edu
Brain Research. Developmental Brain Research
|April 29, 1998
Summary
Dynorphin (DYN) appears in chick auditory nerve terminals during development. This opioid peptide forms chalice-like structures in the cochlear nucleus magnocellularis (NM) around post-hatch day 1, diminishing by the third week.
Area of Science:
- Neuroscience
- Developmental Biology
- Auditory System Research
Background:
- Auditory nerve terminals in the chick cochlear nucleus magnocellularis (NM) were recently found to be immunoreactive for dynorphin (DYN).
- The specialized auditory nerve terminals in birds are known as end-bulbs of Held.
Purpose of the Study:
- To investigate the developmental timeline of dynorphin-immunoreactivity (DYN-I) in auditory nerve terminals within the chick NM.
- To characterize the morphological changes of DYN-I during development.
Main Methods:
- Immunohistochemical analysis of DYN-I in the chick NM across different developmental stages, from embryonic day 13 (E13) to post-hatch weeks.
- Microscopic examination of DYN-I positive structures and their association with NM neurons.
Main Results:
- No DYN-I was detected at E13.
- DYN-I first appeared at E16 as small structures, evolving into rounded, chalice-like end-bulbs of Held by post-hatch day 1 (P1).
- DYN-I was most prominent at P6, surrounding most NM neurons, and significantly decreased by the third post-hatch week.
Conclusions:
- End-bulbs of Held in the chick NM transiently express dynorphin during a specific developmental window.
- The findings provide insights into the developmental expression of opioid peptides in the auditory pathway.