[Stimulation of prolactin secretion with thyroliberin (TRH). In vivo and in vitro studies of metastatic breast cancer].
In 120 Patients with metastatic breast cancer prolactin stimulation tests with 200 mcg TRH i.v. were done. The mechanism of the TRH-induced prolactin release was characterized in vitro. Basal prolactin levels were stimulated in all patients with an average increase of 400% (means basal level 441 mU/l, after stimulation 1753 mU/l). Hyperprolactinemic patients showed the highest absolute prolactin levels following stimulation. Patients with basal prolactin levels under 500 mU/l showed the highest relative increase of prolactin levels (delta = 550%). The prolactin stimulation tests with TRH had no diagnostic advantage compared to the basal prolactin levels in predicting the activity of the disease (basal values: sensitivity 12%, specificity 100%, stimulated values: sensitivity 10%, specificity 99%). During inhibition of plasmaprolactin with bromocriptine, an 330% increase of plasmaprolactin following TRH was observed in vivo. The same was shown in vitro: Pituitary cells cultured in vitro with 10(-6) M dopamine showed an increase of prolactin secretion after coincubation with 10(-7) M TRH. There was a linear increase of the prolactin concentration during the incubation period in dopamine-free cell cultures. The increase of prolactin concentration in vitro was constant during the whole incubation period (5 h), not influenced by the basal prolactin concentration and was seen as early as 30 min in incubation. The in vivo and in vitro results are in agreement with the hypothesis of a rapid, dopamine-independent effect of TRH on the secretion of stored prolactin in the pituitary.
Holtkamp
W
W
Abteilung Hämatologie/Onkologie, Universität Göttingen.
Nagel
G A
GA
D001943:Breast Neoplasms / Q000097:blood*; D046508:Culture Techniques; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D009362:Neoplasm Metastasis; D010902:Pituitary Gland / Q000187:drug effects; D011388:Prolactin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone
D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D004298:Dopamine
Stimulation der Prolaktinsekretion mit Thyreoliberin (TRH). In-vivo- und In-vitro-Untersuchungen beim metastasierten Mammakarzinom.