Radloimmunological Measurement of Follicle Stimulating Hormone and Prolactin in the Dog

Publisher Website
Google Scholar
Abstract
Radioimmunoassays for canine FSH and prolactin were developed and used to quantitate these hormones during proestrus, estrus, pregnancy and nonlactational pseudopregnancy of the bitch. The assay for FSH consists of a rabbit anti-ovine FSH serum, radioiodinated human FSH and NIH-FSH-S4 as standard. Inhibition curves produced by the standard, crude extracts of canine pituitary glands and various canine sera were parallel. FSH in extracts of canine pituitary glands could be quantitatively recovered when added to canine serum. The material in pituitary extracts which inhibited binding of radioiodinated human FSH to the antibody migrated on polyacrylamide electrophoresis gels coincident with radioiodinated human FSH. After injection of GNRH, levels of FSH in serum increased about 50% in 15 min, whereas injections of CB-154 or TRH did not influence levels of FSH. Sensitivity of the FSH assay is 580 pg which is adequate to quantify the concentration of FSH in 200 µl or less of canine serum. The prolactin assay consists of a guinea pig anti-porcine prolactin serum, radioiodinated ovine prolactin and NIH-P-S8 as standard. Sera from dogs during various reproductive states produced inhibition curves which were parallel to the standard curve. The inhibiting material in this assay migrated like radioiodinated ovine prolactin following electrophoresis. Prolactin in extracts of canine pituitary glands was quantitatively recovered after addition to canine serum. Levels of prolactin in serum of male dogs were elevated approximately 5-fold within 20 min after injection of TRH. whereas injection of CB-154 decreased levels of prolactin by 75% 3 h after injection. Injection of GNRH did not affect serum levels of prolactin. Sensitivity of the prolactin assay was 9 pg of NIH-P-S8 which allowed estimation of prolactin concentrations in 200 µl or less of canine sera. During the reproductive cycle, levels of FSH were lowest during proestrus (56.3±8.7 ng/ml) and increased to 167.6±36.9 ng/ml on the first day of estrus. Levels of FSH declined by Day 6 postestrus (69.2± 14.7 ng/ml) then increased to 254.8±27.8 ng/ml in pregnant bitches and 107.5±22.2 ng/ml in pseudopregnant bitches on Days 55-58. Mean levels of prolactin in serum appeared to exhibit cycles of 3-4 days duration and were highest on the days immediately preceding parturition. Levels of prolactin did not differ significantly between pregnant and pseudopregnant bitches.