The Immunological Measurement of Pregnant Mare Serum Gonadotrophin

Abstract

A quantitative haemagglutination\p=m-\inhibition assay was used to measure pregnant mare serum gonadotrophin (PMSG) concentration in six Welsh Mountain pony mares and ten thoroughbred mares during early pregnancy. In both groups of animals PMSG was first detected in the serum between 35 and 41 days of gestation, the limit of sensitivity of the assay being 0\m=.\6i.u. PMSG/ml. The levels rose sharply to reach a maximum at 55\p=n-\60 days of gestation in the ponies and 60\p=n-\65 days in the thoroughbreds. The highest concentrations recorded in both groups were 100\p=n-\112 i.u. PMSG/ml., although one animal never produced more than 11 i.u./ml. The highest concentrations were found in the primiparous ponies. The rate of decline of the PMSG concentrations was not as great as the initial rate of increase, and in all animals PMSG had virtually disappeared from the serum by 120\p=n-\130 days of gestation.The haemagglutination-inhibition assay was evaluated as a pregnancy diagnosis test; 183 sera from 58 mares of various breeds between 41 and 87 days of gestation all gave a positive result, whereas 47 sera from non\x=req-\ pregnant mares, geldings and stallions gave uniformly negative results. An additional 64 sera from 23 mares between 88 and 110 days of gestation gave 62 positives, the two negative reactions being in a pony mare that showed exceptionally low concentrations of PMSG throughout pregnancy.

The dynamic steroid landscape of equine pregnancy mapped by mass spectrometry

“…The maternal ovary is the initial and the principal site of progesterone synthesis in early pregnancy (Squires et al 1974a, Holtan et al 1979. The primary corpus luteum synthesizes progesterone (Condon et al 1979) but, under the influence of equine chorionic gonadotropin (eCG) secreted by the endometrial cups established in early pregnancy (Cole et al 1931, Allen 1969, Squires et al 1979, it also synthesizes estrone sulphate (Daels et al 1990). Luteal tissue weight begins to decline as early as week 7 or 8 (Squires et al 1979), coincident with regression of the endometrial cups and decreasing eCG (Day & Rowlands 1940), as the developing allantochorion gradually becomes the major site of progestogenic support for pregnancy (Squires & Ginther 1975, Holtan et al 1979.…”

An immunochemical demonstration of a pregnancy-specific protein in the horse and its use in the serological detection of early pregnancy

“…The most widely reported preg¬ nancy-specific serum protein in the horse is CG, secreted by the endometrial cups, and detectable in the serum about the 5th week of gestation (Allen, 1969 (1983) and the approach of adsorption of the antisera with non-pregnant horse serum used by these authors would remove antibody specificities to ß2-pregnancy protein. Indeed, this was confirmed when a similar adsorption procedure was carried out on the rabbit anti-pregnant horse antisera described in this paper.…”

“…To date, two horse pregnancy-specific proteins have been reported: horse chorionic gonadotrophin (Cole & Hart, 1930) and mare pregnancy protein-1 (Gidley-Baird et ai, 1983). Horse chorionic gonadotrophin (CG) is secreted by small uterine outgrowths of fetal origin, the endometrial cups (Allen et al, 1973 (Allen, 1969). Mare pregnancy protein-1 (MPP-1) was identified by two-dimensional crossed immunoelectrophoresis using sheep anti-pregnant mare antiserum adsorbed with stallion serum.…”

Simplified purification of equine chorionic gonadotropin (eCG)––an example of the use of magnetic microsorbents for the isolation of glycoproteins from serum

“…Equine chorionic gonadotropin can be detected in mare sera between days 40 and 130 of pregnancy (Aggarwal et al 1980;Cole & Hart 1930;Murphy & Martinuk 1991). Early in this period it attains its highest levels of about 60-80 IU/ml in a bioassay based on rats (Allen 1969). eCG is applied in veterinary medicine as well as in animal breeding.…”