In vivo effects of ovarian steroid hormones on the expressions of estrogen receptors and the composition of extracellular matrix in the anterior cruciate ligament in rats

Atsuhiko Yoshida, Toru Morihara, Yoshiteru Kajikawa, Yuji Arai, Yasushi Oshima, Toshikazu Kubo, Ken Ichi Matsuda, Hirotaka Sakamoto, Mitsuhiro Kawata

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Female athletes have a significantly higher rate of anterior cruciate ligament (ACL) injury than their male counterparts. Sex steroid hormones are considered to have an influence as risk factors for female ACL injuries. We hypothesized that estrogen and progesterone have specific and synergistic influences on the composition of extracellular matrix in ACL. By ovariectomy (OVX) followed by subcutaneous estradiol (E2) and/or progesterone (P4) replacement, 40 female rats were divided into 5 groups: E2, P4, combined E2 and P4 (EP), OVX control, and sham group. After 30 days, using undecalcified sections of knee joints in conjunction with immunofluorescence staining of estrogen receptor α and β (ERα and ERβ), collagen types 1 and 3, and cartilage oligomeric matrix protein (COMP), the immunoreactivities of these proteins in two distinct parts of ACL, proximal and middle portions, were compared semiquantitatively among experimental groups. By E2 replacement, the expressions of ERα in ACL fibroblasts were elevated compared to the OVX group. At the proximal portion, the immunoreactivities of type 1 collagen by E2 replacement, type 3 collagen by P4 replacement, and COMP by E2 or P4 replacement were significantly reduced. At the middle portion, the immunoreactivity of type 3 collagen was significantly elevated by E2 replacement. However, no differences were observed between the sham and OVX groups. These findings suggest that ACL is ER-dependent and that ovarian hormones alter ligament tissue composition, especially at the proximal portion. Female hormonal influences are partly involved in the biological properties of ACL.

Original languageEnglish
Pages (from-to)121-131
Number of pages11
JournalConnective Tissue Research
Volume50
Issue number2
DOIs
Publication statusPublished - Aug 7 2009
Externally publishedYes

Keywords

  • Anterior Cruciate Ligament
  • Estrogen
  • Estrogen Receptor
  • Extracellular Matrix
  • Immunohistochemistry

ASJC Scopus subject areas

  • Rheumatology
  • Biochemistry
  • Orthopedics and Sports Medicine
  • Molecular Biology
  • Cell Biology

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