These studies involve the identification, partial purification and physiological characterization of a prolactin inhibitory activity (PIA) of uterine origin. A dispersed anterior pituitary cell culture system was validated and employed as a bioassay for the PIA. This bioassay coupled with hormone radioimmunoassays and protein assays allowed for the assessment of the amount and potency of the PIA. Initial experiments demonstrated that prolactin (PRL) release from pituitary cells exposed to uterine extract for a 24 h period is inhibited in a dose-dependent manner. Accompanying this inhibition is a dose-dependent increase in intracellular PRL. Hormonal specificity of PIA is suggested by the fact that neither follicle-stimulating hormone nor luteinizing hormone were affected by uterine extract. Estimation of PIA in the uterus and similarly prepared extracts of gut, cardiac muscle and diaphragm reveal that PIA is restricted to uterine tissue. Pharmacological studies using specific receptor blockers indicate that the PIA is neither dopamine nor GABA. PIA is neither proteolytic nor cytotoxic since incubation with standard rat PRL did not decrease the amount of immunoreactive PRL and following uterine extract treatment pituitary cells secrete elevated levels of PRL. / Isolation and culturing of uterine epithelial, stromal and myometrial cells reveal that the PIA is confined to secretions of the epithelial layer. PIA is greater in sera from ovariectomized rats than in sera from ovariectomized-hysterectomized rats. Decrease of PIA in the circulation of hysterectomized rats suggests that the activity is hormonal in nature. / Isolation and purification of PIA involved acid extraction, heat fractionation, gel permeation chromatography, isocratic and reverse-phase high pressure liquid chromatography. These methods followed by amino acid analysis indicate that the PIA is a 63 amino acid polypeptide with an apparent MW of approximately 6900. / In summary, the uterus may function as an endocrine organ by secreting into circulation a non-dopaminergic, non-GABAergic low MW peptide which specifically suppresses PRL release from the anterior pituitary gland. / Source: Dissertation Abstracts International, Volume: 46-01, Section: B, page: 0077. / Thesis (Ph.D.)--The Florida State University, 1984.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75502 |
| Contributors | GOROSPE, WILLIAM CORNELIO., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 265 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
Page generated in 0.0193 seconds