Progesterone Concentrations in the Arterial Plasma of Guinea-Pigs During the Oestrous Cycle

Abstract

The quantities of circulating progesterone and its 20-dihydro metabolites in cyclic female guinea-pigs were estimated by gas chromatography with electron capture detection. Forty-four animals were divided into 13 groups of approximately equal size according to stage of the oestrous cycle. The day on which a lordosis response could be elicited was designated Day 0 of the cycle. In the first few hours of sexual receptivity on Day 0 progesterone levels were 0\m=.\36\ m=+-\ 0\m=.\07 \g=m\g./100 ml. arterial plasma. The ovaries were pre-ovulatory at this stage. After 5 to 12 hr. of behavioural receptivity progesterone levels dropped to 0\m=.\04 \m=+-\0\m=.\01\g=m\g./100 ml. plasma, and at the termination of receptivity (just after ovulation) progesterone was almost completely undetectable.The concentration of progesterone increased gradually after ovulation reaching a peak about Day 9 (0\m=.\30 \ m=+-\ 0\m=.\05 \g=m\g./100 ml. plasma) and then fell to undetectable levels by Day 15. The 20-dihydro metabolites of progesterone were not present in significant quantities at any stage of the cycle.It is concluded that in guinea-pigs a surge of progesterone occurs approximately 8 to 12 hr. before ovulation and coincides with the onset of oestrous behaviour. The plasma concentration of progesterone at this pre-ovulatory stage is at least as high as that measured at any point during the luteal phase.

Progesterone Levels During the Oestrous Cycle and Pregnancy in the Cuis, Galea Musteloides

“…565-567). Progesterone concentration in plasma and ovarian tissue in the guinea-pig has been reported by Rowlands & Short (1959), Heap & Deanesly (1966), Heap, Perry & Rowlands (1967) and Feder, Resko & Goy (1968). The present study examines the progesterone levels in arterial plasma and in the CL of a few cyclic cuis and a small series of pregnant cuis.…”

Age- and hormone-related changes in vaginal smear patterns in the gray-tailed vole, Microtus canicaudus

“…Vaginal epithelial cycles and the hormone changes associated with these cycles have been character¬ ized for many spontaneously ovulating rodents (Feder, Goy & Resko, 1967;Feder, Resko & Goy, 1968; Leavitt & Blaha, 1970;Lukaszewska & Greenwald, 1970;Challis, Heap & Illingworth, 1971; Baranczuk & Greenwald, 1973;Butcher, Collins & Fugo, 1974;Campbell, Ryan & Schwartz, 1976). In these rodents, the regular follicular cycles associated with spontaneous ovulation are reflected in predictable changes in plasma oestrogen and progesterone and, consequently, in changes in vaginal epithelium.…”

The effect of deslorelin acetate on the oestrous cycle of female guinea pigs

“…Previously, it has been shown that there is a significant elevation of plasma progesterone (P 4 ) coincident with the luteal phase (dioestrus) in guinea pigs (Feder et al 1968;Challis et al 1971;Blatchley et al 1976;Garis and Foreman 1984), whereas fluctuations of plasma oestradiol (E 2 ) levels occur throughout the oestrous cycle (Chalis et al 1971;Croix and Franchimont 1975;Garris and Foreman 1984;Westfahl and Vekasy 1988;Hutz et al 1990).…”