PLASMA PROGESTERONE LEVELS IN GUINEA-PIGS ACTIVELY IMMUNIZED AGAINST PROSTAGLANDIN F2α, HYSTERECTOMIZED OR TREATED WITH INTRA-UTERINE INDOMETHACIN

Abstract

Five guinea-pigs actively immunized against a prostaglandin F2alpha(PGF2alpha)-bovine serum albumin conjugate showed elongated oestrous cycles. During these, corpora lutea were maintained in a functional secretory state as indicated by plasma progesterone levels. The results are compatible with the view that the PGF2alpha antibodies neutralized the PGF2alpha released from the uterus and thus prevented its normal luteolytic effect. Similar patterns of progesterone secretion were observed in two hysterectomized animals and in two animals with intra-uterine implants of indomethacin.

Effect of actinomycin D on uterine prostaglandin production and oestrous cycle length in guinea-pigs

“…The antibody had adequate sensitivity (limit 20 pg) and specificity (see Table 1 in Poyser & Horton, 1975) and the results obtained in the present study were in the expected range. The intra-and inter-assay coefficients of variation were 10-8 and 12-5% respectively.…”

“…Progesterone was measured by radioimmunoassay using an antibody raised and tested by Dighe & Hunter (1974) and assessed for its suitability for use in the laboratory by Poyser & Horton (1975). The antibody had adequate sensitivity (limit 20 pg) and specificity (see Table 1 in Poyser & Horton, 1975) and the results obtained in the present study were in the expected range.…”

Effect of active immunization of pre-partum and post-partum cows against prostaglandin F-2 on lifespan and progesterone secretion of short-lived corpora lutea

“…Furthermore, prostaglandin F-2a has been implicated in resumption of ovarian activity in post-partum dairy cows (Gilbault et al, 1987). A characteristic of active immunization is that it frequently increases circulating concentrations of the antigen against which the animal is immunized, presumably due to a decrease in the metabolic clearance rate associated with the antibody-bound molecule (Scaramuzzi et al, 1973;Sheldrick et al, 1980 (Horton & Poyser, 1974;Poyser & Horton, 1975). In the present study, cows in the post-partum PGF-2ct group which responded to immunization exhibited either luteal maintenance or oestrous cycles of normal length after first ovulation.…”

“…Both active and passive immunization against PGF-2a lengthened the functional lifespan of corpora lutea in sheep (Scaramuzzi & Baird, 1976;Fairclough et al, 1981), guinea-pigs (Horton & Poyser, 1974;Poyser & Horton, 1975) and cattle (Fairclough et al, 1981;Chang et al, 1987). Therefore, the objective of this study was to determine whether active immunization of pre-partum and post-partum cows against PGF-2a would extend the lifespan and progesterone secretion of short-lived corpora lutea.…”

Utero-ovarian relationships in placental mammals : role of uterus and embryo in the regulation of progesterone secretion by the corpus luteum. A review

“…While changes in the uterus depend on ovarian steroids, the uterus, in return, can modulate ovarian activity. These (Poyser and Horton, 1975) ; 2) hysterectomy is followed by luteal maintenance of progesterone secretion for several months, as in ewe, cow, sow and mare (see Anderson, Bland and Melampy, 1969 ;Stabenfeldt et al, 1974 ;Schirar and Martinet, 1982) ; 3) hysterectomy slows down the gradual drop in the circulating progesterone level that marks the end of the luteal phase as in pseudopregnant rat, mouse, hamster and rabbit (mouse, hamster : De Feo, 1967 ;Duby et al, 1969 ;Crister, Rutledge and French, 1981 ;rat : De Feo, 1967 ;Rothchild and Gibori, 1975 ;De Greef, Dullaart and Zeilmaker, 1976 ;rabbit : Hilliard et al, 1974 ;Satoh et al, 1980) ; 1 4) hysterectomy has no effect either on the length of the activity of corpus luteum or on the amounts of progesterone secreted as in ferret, mink, spotted skunk and European badger (Deanesly and Parkes, 1933 ;Canivenc, Bonnin and Lajus, 1966 ;Duby, 1972 ;Mead and Swannack, 1978 ;Canivenc, Bonnin and Relexans, 1962), or in woman and macaque (Neill, Johansson and Knobil, 1969 ;Doyle et aL, 1971 ;Fraser et aL, 1973 ;Castracane, Moore and Shaikh, 1979) ; 5) hysterectomy reduces the duration of luteal activity by hastening the drop in progesterone secretion at the end of the luteal phase as in dog (Hadley, 1975b ;Baker et al, 19801. When hysterectomy extends the activity of corpus lute!m, it suppresses the PGF 2a source involved in luteolysis. The inhibition of prostaglandin synthesis by indomethacin has the same effects on progesterone secretion as hysterectomy (rat, hamster : Lau, Saksena and Chang, 1975 ;rabbit : Satoh et al, 1980 ; guinea-pig : Horton and Poyser, 1973 ;Poyser and Horton, 1975 ;…”