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Thyrotropin-releasing hormone activity in the human placenta
The Journal of Clinical Endocrinology and Metabolism
|March 1, 1979
Summary
Researchers discovered thyrotropin-releasing hormone (TRH) in human placenta extracts, exhibiting biological and immunological activities. This placental TRH functions similarly to synthetic TRH, suggesting endogenous origins within the placenta.
Area of Science:
- Endocrinology
- Reproductive Biology
- Biochemistry
Background:
- Human placentas contain various biologically active substances.
- Thyrotropin-releasing hormone (TRH) is a key regulator of thyroid-stimulating hormone (TSH) release.
Purpose of the Study:
- To investigate the presence and characteristics of TRH in human placental extracts.
- To compare the properties of placental TRH with synthetic TRH.
Main Methods:
- Extraction of TRH from term human placentas using acetic acid.
- Quantification of TRH using radioimmunoassay (RIA).
- Characterization of placental TRH via immunoassay inhibition curves, gel chromatography (Sephadex G-10), in vitro TSH release assays, and serum degradation studies.
Main Results:
- TRH immunological activity was detected in all placental extracts, averaging 19.8 +/- 3.3 pg/mg protein.
- Placental TRH demonstrated identical immunoassay inhibition slopes and similar chromatographic elution profiles compared to synthetic TRH.
- Both placental TRH and synthetic TRH stimulated TSH release from rat pituitaries in vitro.
- Human serum degraded placental TRH and synthetic TRH similarly.
- Placental tissue did not accumulate exogenous TRH, indicating endogenous production.
Conclusions:
- Human placentas contain TRH with immunological and biological activities comparable to synthetic TRH.
- The findings suggest that TRH is synthesized endogenously within the human placenta.