Changes in gap junction connexin-43 messenger ribonucleic acid levels associated with rat ovarian follicular development as demonstrated by in situ hybridization.
OBJECTIVE
The purpose was to evaluate the changes in gap junction connexin-43 messenger ribonucleic acid levels associated with rat ovarian follicular development. Gap junctions connect the plasma membranes of adjacent cells through cell-to-cell channels, allowing synchronization of cellular events, including ovarian follicular development. Ovarian gap junctions consist of the protein connexin-43.


METHODS
We used the hypophysectomized immature rat treated with estrogen or gonadotropins as a model to study the ovarian regulation of connexin-43 messenger ribonucleic acid. In situ hybridization with radiolabeled riboprobes was used to localize and quantitate connexin-43 messenger ribonucleic acid.


RESULTS
We demonstrated that connexin-43 messenger ribonucleic acid was localized to follicular granulosa cells. Estrogen significantly up-regulated connexin-43 messenger ribonucleic acid (91%), whereas gonadotropins that stimulate ovulation and corpus luteum formation completely down-regulated the connexin-43 gene. These results correlate closely with previous immunohistochemical studies of connexin-43 protein.


CONCLUSIONS
The positive correlation between follicular development and granulosa cell content of connexin-43 messenger ribonucleic acid is caused by transcriptional activation of the gap junction connexin-43 gene, posttranscriptional stability of connexin-43 messenger ribonucleic acid, or both. Future studies will determine the molecular mechanisms of hormonal regulation of the connexin-43 gene.
Department of Obstetrics and Gynecology, University of Chicago, Illinois.
J R
JR
Schreiber
M W
MW
Beckmann
D
D
Polacek
P F
PF
Davies
D000818:Animals; D017630:Connexins; D003338:Corpus Luteum / Q000187:drug effects / Q000502:physiology; D015536:Down-Regulation; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D006062:Gonadotropins / Q000494:pharmacology; D007016:Hypophysectomy; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000187:drug effects / Q000235:genetics*; D006080:Ovarian Follicle / Q000502:physiology*; D010060:Ovulation / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013799:Theca Cells / Q000187:drug effects; D015854:Up-Regulation
D017630:Connexins; D004967:Estrogens; D006062:Gonadotropins; D008565:Membrane Proteins; D012333:RNA, Messenger