Evidence for a rapid in vivo effect on estradiol-17 beta on prolactin secretion in ovariectomized rats.

Abstract

Repeated intraarterial injections of synthetic thryrotropin releasing hormone (TRH, 1 microgram/rat) increased plasma prolactin levels 4 hours after a single subcutaneous injection of 10 micrograms estradiol-17 beta (E2-17 beta) in rats ovariectomized 1, 2 or 4 weeks and at 2 hours after E2-17 beta injection in rats ovariectomized for 6 weeks. The effect of TRH was still present at 24 but not 48 hours after estradiol treatment. TRH-induced increases in plasma prolactin were similar in groups of rats treated with 10 micrograms E2-17 beta (s.c.) or implanted with 0.5 cm Silastic capsules of crystalline E2-17 beta (s.c.) whereas smaller, yet significant, TRH-induced increases in plasma prolactin were observed in rats injected s.c. with 1.0 microgram E2-17 beta. Single intraarterial injections of TRH at 4 or 8 hours after E2-17 beta treatment induced increases in plasma prolactin similar in magnitude to those observed at the same times after E2-17 beta in rats given repeated TRH injections. No effect of TRH was observed in ovariectomized rats given sesame oil and E2-17 beta treatment did not influence plasma prolactin in rats given saline instead of TRH. Intraarterial administration of serotonin creatinine sulfate (5-HT, 10 mg/kg body weight) induced marked increases in plasma prolactin in rats ovariectomized for 4 weeks which were potentiated at 2 and 6 hours after E2-17 beta (10 micrograms) treatment. The data show that estradiol has a fairly rapid stimulatory effect on plasma levels of prolactin induced by two different secretagogues but the exact site and mechanism of action remain unresolved.

• Authors: D M Lawson
• Journal: Endocrine research communications (Endocr Res Commun) Vol. 6 Issue 2 Pg. 135-48 ( 1979) ISSN: 0093-6391 [Print] United States
• PMID: 116836 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Drug Implants
• Serotonin
• Estradiol
• Thyrotropin-Releasing Hormone
• Prolactin

Topics

• Animals
• Castration
• Drug Implants
• Drug Synergism
• Estradiol (administration & dosage, pharmacology)
• Female
• Injections, Subcutaneous
• Prolactin (blood)
• Rats
• Serotonin (pharmacology)
• Thyrotropin-Releasing Hormone (pharmacology)
• Time Factors