Abstract
Summary
Anterior pituitaries (AP) were aseptically removed from sexually mature female Sprague Dawley rats and cultured in an air environment for a period of 54 days with a medium change every 3 days. The prolactin activity in the medium was determined by the intradermal crop gland bioassay, by disc electrophoresis-microdensitometric analysis (ED) and by radioimmunoassay (RIA). Prolactin activity was detected in the medium by all three methods up to the 33rd day of culture. There was a decrease in medium prolactin content up to the 15th day and an increase thereafter. Examination of the medium by disc electrophoresis revealed the loss of the growth hormone component beginning on the 15th day medium change. The three methods used to estimate prolactin activity produced results which were in general agreement on a relative basis. The ED and RIA methods, however, were more closely related to each other than to the crop gland assay. On an absolute basis (μg-μg) the ED method overestimated the prolactin content by a factor of 2-3 while the RIA underestimated prolactin content by 1 or less order of magnitude when compared to bioassay values. The reason for these differences was not apparent.
The authors would like to acknowledge the technical assistance of Mrs. Rafaela Ubals Lavker. Ovine prolactin (NIH-P-S-7) and human growth hormone (NIH-GH-HS-1207A) were received as a gift from the NIH Endocrine Study Section; rat prolactin (NIH-NIAMD-RP-1) was received as a gift from Dr. A. Parlow through the Endocrine Study Section of the National Institute for Arthritis and Metabolic Diseases.
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