Localization of endothelin receptor messenger ribonucleic acid in the rat ovary and fallopian tube by in situ hybridization

Rat mRNAs encoding two subtypes of the endothelin (ET) receptor (ET(A) and ET(B)) were studied in the rat ovary and fallopian tube by means of Northern blotting and in situ hybridization. The mRNA transcripts for the endothelin- 1-specific type receptor (ET(A)) in pooled RNA from the ovary and fallopian tube were 4.2 and 5.2 kilonucleotides, and that for the nonselective type receptor (ET(B)) was 4.7 kilonucleotides; these were similar to transcripts for endothelin receptors from other tissues. ET(A) mRNA expression was abundant in the muscle cell layer of the fallopian tube, but low in the ovary. On the other hand, ET(B) mRNA was abundant in the granulosa cells in the developing follicles, but low in atretic follicles and absent in the fallopian tube. These results demonstrated that the mRNAs for the two subtypes of the rat endothelin receptor have different expression profiles in the ovary and fallopian tube. ETs may mainly affect the granulosa cells in the dominant follicles as well as the muscle cells of the fallopian tube through ET(B) and ET(A), respectively.