Effect of oestrogen on pregnancy of guinea-pigs

Evans, John J.; Sin, Iris L.; Merrick, Anne Y.; Kelleher, P. R.

doi:10.1530/jrf.0.0620205

Cited by 7 publications

(2 citation statements)

References 11 publications

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“…However, endometrial PGF-2a synthesizing capacity was not increased. Despite this apparent lack of any immediate effect the treatment of pregnant guinea-pigs with oestradiol on Days 10 and 11 does adversely affect the pregnancy from Day 30 onwards (Evans, Sin, Merrick & Kelleher, 1981). In non-pregnant guinea-pigs, the oestradiol treatment used universally stimulates increases in uterine PGF-2a output and endometrial PGF-2a synthesizing capacity, and a decrease in ovarian progesterone output (Blatchley et al, 1972;Blatchley & Poyser, 1974;Naylor & Poyser, 1975;Wlodawer et al, 1976;Poyser, 1983a, b).…”

Section: Discussionmentioning

confidence: 99%

Prostaglandin production by the early pregnant guineapig uterus in relation to implantation and luteal maintenance, and the effect of oestradiol

Poyser¹

1984

Reproduction

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The outputs of prostaglandin (PG) F-2 alpha and PGE-2, but not of 6-oxo-PGF-1 alpha, from the guinea-pig uterus were significantly lower on Days 7 and 15 of pregnancy than on the corresponding days of the cycle. Uterine PGF-2 alpha output increased 28-fold between Days 7 and 15 of the cycle but only 4- to 5-fold between these same days of pregnancy. Uterine PGE-2 and 6-oxo-PGF-1 alpha outputs increased 2- to 3-fold between Days 7 and 15 of the cycle and of pregnancy. Endometrial PGF-2 alpha synthesizing capacity was 60-70% lower on Days 7 and 15 of pregnancy than on the corresponding days of the cycle, although it increased 2-fold and 2.5-fold between these days of pregnancy and of the cycle, respectively. Endometrial PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities showed no significant variation amongst Days 7 and 15 of the cycle and of pregnancy, except that endometrial PGE-2 synthesizing capacity was lower on Day 7 of the cycle. Oestradiol treatment (10 micrograms s.c. daily from Days 10 to 14 of pregnancy) did not affect plasma progesterone concentrations, uterine 6-oxo-PGF-1 alpha output, and endometrial PGF-2 alpha, PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities in 9/12 guinea-pigs when examined on Day 15. Uterine PGF-2 alpha and PGE-2 outputs increased 3- and 1.5-fold, respectively, in these guinea-pigs, but were still much lower than the outputs from the Day-15 non-pregnant uterus. The pregnancies appeared unaffected in these oestradiol-treated guinea-pigs. In the other 3 oestradiol-treated animals, uterine PGF-2 alpha output was 20- to 30-fold higher than in untreated, pregnant guinea-pigs on Day 15, and 2- to 3-fold higher than in Day-15 non-pregnant guinea-pigs. Uterine PGE-2 and 6-oxo-PGF-1 alpha outputs also tended to be higher in these treated guinea-pigs. In these 3 guinea-pigs, endometrial PGF-2 alpha, PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities were 4.0-, 3.4- and 2.5-fold higher, respectively, than in untreated, pregnant guinea-pigs on Day 15, and tended to be higher than in Day-15 non-pregnant guinea-pigs. Plasma progesterone concentrations were much lower in these 3 animals than in the other 9 treated with oestradiol, and also much lower than in untreated, pregnant guinea-pigs on Day 15.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Discussionmentioning

confidence: 99%

Prostaglandin production by the early pregnant guineapig uterus in relation to implantation and luteal maintenance, and the effect of oestradiol

Poyser¹

1984

Reproduction

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“…Following ether extraction plasma progesterone was as¬ sayed by the method of Evans et al (5) using an antiserum supplied by Dr J France (Postgraduate School of Obstet¬ rics and Gynaecology, National Women's Hospital, Auck¬ land).…”

Section: Progesterone Radioimmunoassaymentioning

confidence: 99%

Oxytocin influences preovulatory follicular development and advances ovulation in rats

Robinson

Evans²

1991

Acta Endocrinologica

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Oxytocin has been shown to advance gonadotropin secretion in pro-estrus rats. The effects that oxytocin-induced changes have on the ovary were investigated in this study. Oxytocin administered to rats at proestrus 09.00 h, 10.00 h and 11.00 h advanced follicular growth, progesterone secretion, and the time of ovulation. However, both treated and control groups of rats ovulated similar numbers of oocytes and the oocytes released were of similar fertility. Because oxytocin has been shown to induce early LH and FSH release the effects of oxytocin administration on the ovary were possibly an indirect action involving the pituitary. The results of this investigation indicate that exogenous oxytocin alters, the timing but not the fertility of periovulatory events.Oxytocin has been shown to influence follicular de¬ velopment and ovulation in cyclic mice (1). Al¬ though the hormonal factors mediating this effect were not determined, it has since been demon¬ strated that oxytocin administered to rats on the morning of pro-estrus could advance the LH surge (2). A vital role for oxytocin at pro-estrus was in¬ dicated by abolishing the in vivo LH surge with oxytocin receptor antagonists (2,3). A direct gonadotropin-releasing activity of oxytocin on rat pitu¬ itary cells in vitro, acting via specific receptors has been established (4). Whether gonadotropins released by oxytocin treatment of pro-estrus rats have normal physio¬ logical activity was not demonstrated. Therefore the current study was designed to determine if oxy¬ tocin treatment altered follicular growth and ovu¬ lation, and the ability of ovulated oocytes to be fer¬ tilized in vivo. Material and Methods AnimalsFemale Wistar rats were obtained at 12 weeks of age.They were housed 5 animals to a cage under controlled humidity, temperature (22°C) and lighting (lights on be¬ tween 05.00 and 19.00 h). Rats were provided with pel¬ leted food and fresh water ad libitum. Vaginal smears were taken each morning to monitor estrous cycles. Only those rats exhibiting three or more consecutive four-day cycles were used.Effect of oxytocin on follicular development and ovulation Experimental rats received injections of oxytocin (Syntocinon®, Sandoz, Switzerland) (10 mlU/g ip) at pro-estrus : 09.00 h, pro-estrus: 10.00 h, and pro-estrus: 11.00 h (2) in a volume of 0.25 ml. Control animals received equiv¬ alent injections of saline. At 3-h intervals between proestrus: 12.00 h and estrous: 06.00 h groups of 5 rats were bled and killed by cardiac punction under pentobarbitone anesthesia. Ovulation rates (ova ovulated per rat) were determined by the retrieval of ova from the oviducts. The ovaries were removed for histological processing. For the measurement of plasma progesterone, blood was col¬ lected from the tail vein of additional rats under light halothane anesthesia. Effect of oxytocin on oocyte fertilization in vivoThe ability of oocytes ovulated after oxytocin treatment to be fertilized and develop into normal litters was investi¬ gated. Pro-estrus rats were mated after receiv...

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Progesterone-binding globulin and progesterone in guinea-pigs after ovariectomy, abortion and parturition

Evans

Sin

White

1982

Journal of Steroid Biochemistry

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Effect of oestrogen on pregnancy of guinea-pigs

Cited by 7 publications

References 11 publications

Prostaglandin production by the early pregnant guineapig uterus in relation to implantation and luteal maintenance, and the effect of oestradiol

Prostaglandin production by the early pregnant guineapig uterus in relation to implantation and luteal maintenance, and the effect of oestradiol

Oxytocin influences preovulatory follicular development and advances ovulation in rats

Progesterone-binding globulin and progesterone in guinea-pigs after ovariectomy, abortion and parturition

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