Development of multidrug resistance type I Cmdr1 expression in chicken embryonic gonads

K. Yamada, N. Shibuya, S. Aramaki, S. Okuno, T. Soh, N. Yamauchi, M. A. Hattori

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A primary role of P-glycoprotein (P-gp), encoded by the multidrug resistance type I gene, is to protect against naturally occurring xenotoxics. Recently, the preferential expression of chicken multidrug resistance type I (Cmdr1) was identified in the embryonic gonads during the early periods of development. Here we investigated the expression of Cmdr1 and P-gp in the gonads during embryogenesis, and compared to that in the ovarian follicles of domestic hens (Gallus gallus). As revealed by immunohistochemistry, P-gp was highly expressed in theca cells of mature follicles, whereas the expression was low in immature follicles. Immunohistochemical analysis showed that expression of Cmdr1-type P-gp was very low in embryonic gonads. Cmdr1 mRNA was undetectable in the gonads of 5-day embryos (E5) by RT-PCR, whereas Cmdr1 mRNA was significantly detectable in the developing gonads at E9 and E21. In the testicular tissues, germ cells were distributed along developing seminiferous cords as identified by a specific marker gene, whereas Cmdr1-type P-gp positive cells were observed evenly on testicular tissues. Collectively, it is concluded that Cmdr1 expression is initiated in the chicken ovary and testis after sexual differentiation, but expression of Cmdr1-type P-gp is very low through embryogenesis.

Original languageEnglish
Pages (from-to)928-933
Number of pages6
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Issue number4
Publication statusPublished - Aug 2007

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physiology
  • Molecular Biology


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