Expression Patterns of Cav1.3 in the Developing Stria Vascularis of Sprague-Dawley Rats.

Background: Although multiple functions of Cav1.3 in adult rat cochlea have been explored, its role in developing stria vascularis (SV) of Sprague-Dawley (SD) rats has rarely been reported.

Methods: Sprague-Dawley rats from postnatal 0 to 21 days (p0-p21) were utilized for the experimental model and classified into 4 groups by age randomly: p0, p7, p14, and p21. p3 SD rats were employed to culture primary marginal cells (MCs). The quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunofluorescence technique were employed to identify Cav1.3 in vivo. Immunocytochemistry was applied to explore the expression of Cav1.3 in vitro.

Results: Quantitative reverse transcription polymerase chain reaction showed that the Cav1.3 calcium channel gene (CACNA1D) was measured in the cochlear lateral wall (STV), which included SV and spiral ligament. Immunofluorescence photographs revealed that Cav1.3 was intensively expressed in the SV, weakly expressed in the spiral ligament and spiral prominence. In the SV, immunofluorescence labeling of Cav1.3 was present in MCs, intermediate cells, and basal cells. Immunocytochemistry confirmed that Cav1.3 was expressed in the cytomembrane of the MCs. Moreover, the expression of Cav1.3 was increased in the developmental STV at both the protein and mRNA levels.

Conclusion: Cav1.3 was mainly present in the cytomembrane of MCs in the SV of postnatal SD rats. Additionally, Cav1.3 protein and mRNA increased with development in the cochlear lateral wall of SD rats, including in the SV. The alteration of Cav1.3 expression may influence the homeostasis of ions and benefit the normal function and development of the cochlea.