Changes in oestrone sulphate concentrations in peripheral plasma of Pony mares associated with follicular growth, ovulation and early pregnancy

Abstract

Summary. A simple and rapid ( < 2 h) immunoassay method has been developed based upon a novel separation technique called LIDIA (Ligand Differentiation Immunoassay), enabling direct estimation of the concentration of oestrone sulphate in ethanolic extracts of blood plasma. An antiserum raised against oestrone-3-glucuronyl\p=n-\BSA was used which showed a higher cross-reaction with the sulphate than the glucuronide metabolite. The assay had a sensitivity of 5\m=.\2 pg/tube and acceptable inter-( < 18%) and intra-(<8\m=.\5%)assay precision. Analysis of samples of peripheral venous plasma obtained daily from Pony mares showed that the mean concentration of oestrone sulphate started to rise from a baseline value ( < 300 pg/ml) at 6 days and reached a peak ( > 850 pg/ml) at 2 days before follicular rupture as determined by rectal palpation. Progesterone concentrations only started to rise above baseline ( < 0\m=.\5 ng/ml) on the day of ovulation and reached a peak 8 days later. Analysis of samples obtained during the first 30 days of pregnancy showed that there was no increase in oestrone sulphate at the time oestrus would have been expected had the mares not conceived.

Estimating Insemination Time in Mares on the Basis of the Urinary Concentration of Estrone-Sulphate.

“…These results agree with reports showing that in 75% of the mares, the total plasmatic estrogen concentrations reached a peak at D-2. Similar findings were obtained in measurements of urinary estrogens [9] and plasmatic E1S [7] since E1S was thought to be cleared directly into the urine. The plasma dynamic is therefore expected be reflected in the urine [4].…”

“…Prediction of ovulation based on such a decline in the E1S concentration was mentioned in several earlier reports [1,6,7,9] but previous methods used in measuring hormones have involved lengthy procedures (overnight) and high costs (radioimmunoassay) [1,3,10]. The present experiment, however, was able to use a simple and faster method (2 hr) for measuring daily urinary E1S to estimate the ovulation time in mares based on the changes in the E1S concentration.…”

“…In both cases, estrogen levels registered a gradual increase during the follicular phase and then a decrease a few days before ovulation [6][7][8]. The EC in the urine is ten times higher than in the plasma due to the kidney's concentrating capacity and the resistance of EC metabolites to rapid degradation [3].…”

Development and Evaluation of a Rapid Enzyme-immunoassay System for Measurement of the Urinary Concentration of Estrone-3-glucuronide in a Female Giant Panda (Ailuropoda melanoleuca)

“…The fact that our data on the E1G concentrations and presenting behavior matched those of previous reports [18,23] proves that our EIA system is suitable for measuring urinary E1G to detect estrus in the female giant panda. Prediction of estrus and ovulation based on these types of changes in the E1G concentration has been reported in several previous studies [27][28][29][30]; however, the previous methods used for measuring steroids, such as RIA, involved time-consuming, risky and expensive procedures [22,27,31]. The EIA system developed in the present study, however, is a simple and fast method (3 h) for measuring daily urinary E1G.…”

Determination of conjugated oestrogens in maternal blood plasma and urine for pregnancy diagnosis and monitoring of foetal well-being in the mare

“…On the other hand, mares with threatened aborlions showinq normal oestrooen concentrations maintained pregnancy throughout the time of observation in the clinic, Apaft from subnormal oestrogen concentrations also extraor{rnarily high values can be indicative for impaired gestation (Hoffmann et al, 1996), Furthermore, twin pregnancies are associated with oestrogen levels in the upper range. Prior to the onset of placental oestrogen production determination of estrone sulfate of ovarian origin can also be applied, However, pregnancy diagnosis may be problematic due to slightly overlapping values between 1 to 2.5 ng/ml likewise occurring in mares at oestrus (Makawiti et al, 1983;Koskinen et al, 19Bg) and a minor fraction of eCGpositive mares (Schuler, 1998). However, since the detection of eCG and not the positive outcome of gestation was used to classify animals as pregnant, no information is available if pregnancy was still intact at the time of testing as eCG production can persist for a relatively long time after foetal death (Hoffmann et al,, 1996).…”