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Appearance of glucocorticoid receptors in the inner ear of the mouse during development
S Erichsen1, D Bagger-Sjöbäck, L Curtis
1Department of Otorhinolaryngology, Karolinska Hospital, Stockholm, Sweden.
Insights
Glucocorticoid receptors appear in the developing inner ear, with expression changing significantly from embryonic stages to adulthood. This pattern suggests a role in both inner ear maturation and adult function.
Area of Science:
- Developmental biology
- Neuroscience
- Otolaryngology
Background:
- Glucocorticoid receptors (GRs) are critical for cellular function and development.
- The expression pattern of GRs in the developing inner ear is not well understood.
Purpose of the Study:
- To investigate the temporal expression of glucocorticoid receptors in the developing and adult mouse inner ear.
Main Methods:
- Immunohistochemical staining of cryosections from CBA mice at various embryonic and postnatal developmental stages.
- Analysis of both vestibular and cochlear regions using the avidin-biotin complex (ABC) method.
Main Results:
- Glucocorticoid receptor staining was faint at embryonic day 19 and became visible at postnatal day 1.
- Expression levels decreased between postnatal days 2-5, then increased until postnatal day 14, reaching an adult pattern.
- The developmental expression curve of GRs in the inner ear is non-linear.
Conclusions:
- The dynamic expression of glucocorticoid receptors during inner ear development suggests a role in embryological maturation.
- The observed patterns indicate a potential functional significance of GRs in the adult inner ear.
Abstract:
CBA mice were sacrificed at different ages of developments at embryonic day 13 (E13), E14, E16, E19, E20 and postnatal day 1 (P1), P2, P3, P4, P6, P8, P10, P14, P16, P18, P20 and P30. The temporal bones were quickly removed and deep frozen in order to prepare cryosections for immunohistochemical staining with polyclonal antibodies against glucocorticoid receptors. The avidin-biotin, ABC-method was used to visualize binding. Both the vestibular and the cochlear regions of the inner ear were analysed. A faint staining of the crista ampullaris, the utricle and the cochlear duct was seen at E19; and staining became clearly visible at P1. A decrease in labelling was found at day 2-5 post partum whereafter an increased staining was again noticed until postnatal day 14 when an adult pattern was observed. The appearance of glucocorticoid receptors in the inner ear during development does not follow a linear curve. Further, the labelling pattern may indicate an impact of glucocorticoid receptors on the embryologic maturation itself as well as a functional role in the adult ear.