Studies on the endocrinology of parturition in the guinea-pig

Dv, Illingworth; Ackland, Nicola; Am, Burton; Challis,; Heap, R. B.; Js, Perry

doi:10.1530/jrf.0.0330361

Cited by 2 publications

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“…However, hypophysectomized guinea-pigs can give birth to live young (Pencharz & Lyons, 1934;Illingworth, Ackland, Burton, Challis, Heap & Perry, 1973). No oxytocin can be detected in the maternal plasma of these animals during parturi¬ tion, but it is present in foetal plasma.…”

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confidence: 98%

Placental Transfer of Oxytocin in the Guinea-Pig and Its Release During Parturition

Am¹,

Illingworth²,

Challis³

et al. 1974

Journal of Endocrinology

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Oxytocin levels in pregnant and parturient guinea-pigs were studied by means of a sensitive and specific radioimmunoassay. Oxytocin was released from the maternal pituitary in substantial amount only during the expulsive phase of labour, when the mean concentration in carotid arterial blood in five animals was 503 pg/ml plasma (range 96\p=n-\2900 pg/ml). Oxytocin was not found in the plasma of the first born at the moment of birth, but was usually detected in amounts ranging from 96 to 455 pg/ml in those born subsequently. The mean half-time of oxytocin in the maternal circulation during late pregnancy was 62 \ m=+-\ 7\m=.\5 (s.e.m., n = 5) s. In-vivo experiments showed that the placenta was permeable to oxytocin in both directions.

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mentioning

confidence: 98%

Placental Transfer of Oxytocin in the Guinea-Pig and Its Release During Parturition

Am¹,

Illingworth²,

Challis³

et al. 1974

Journal of Endocrinology

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“…In guinea-pigs hypophysectomized as early as the first day after mating, pregnancy continued normally (Heap, Perry & Rowlands, 1967) and live foetuses were carried to term (Illingworth, Ackland, Burton, Challis, Heap & Perry, 1973a;Ash, Challis, Harrison, Heap, Illingworth, Perry & Poyser, 1973;Illingworth, Perry, Ackland & Burton, 19736). Complete pelvic relaxation and spontaneous delivery was observed only in those animals that received daily injections of cortisone acetate (12-5 mg, s.c.) from day 55 of pregnancy, and in these delivery was protracted.…”

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confidence: 99%

Parturition in the Guinea-Pig; Plasma Levels of Steroid Hormones, Steroid-Binding Proteins, and Oxytocin, and the Effect of Corticosteroids, Prostaglandins and Adrenocorticotrophin

Illingworth¹,

Challis²,

Ackland³

et al. 1974

Journal of Endocrinology

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Parturition in the guinea-pig is not preceded by any consistent change in the maternal plasma concentrations of progesterone, total unconjugated oestrogens or corticosteroids, or by a significant change in the concentration of progesterone-binding globulin (PBG). The onset of parturition was delayed by high doses of oestrogens (stilboestrol and oestradiol), but was not affected by oestriol or an antiserum raised against oestradiol. Premature parturition was achieved by the intra-carotid infusion of adrenocorticotrophin or prostaglandins (PGF2\g=a\, PGE2, I.C.I. 80,996) in conscious animals with indwelling catheters. I.C.I. 80,996, a potent analogue of PGF2\g=a\, induced parturition in all seven guinea-pigs treated; delivery occurred within 6 h of starting the infusion in six animals, and within 48 h in the seventh. The undesirable side-effects that accompanied treatment with PGF2\g=a\ or PGE2 were not encountered with I.C.I. 80,996. Parturition induced experimentally resembled normal delivery but was not preceded by any significant change in the maternal levels of progesterone, total unconjugated oestrogens, corticosteroids, PBG or CBG in the circulation. Oxytocin was not detected until the delivery of the first foetus.Parturition was not induced by maternal or foetal injections of corticosteroids or dexamethasone. Earlier findings are confirmed that the foetal adrenal grows steadily throughout late pregnancy and, unlike the foetal lamb adrenal, undergoes no rapid phase of growth immediately before term. Foetal adrenal weight decreased relative to foetal body weight.The trigger for parturition in this species remains unidentified.

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Studies on the endocrinology of parturition in the guinea-pig

Cited by 2 publications

References 0 publications

Placental Transfer of Oxytocin in the Guinea-Pig and Its Release During Parturition

Placental Transfer of Oxytocin in the Guinea-Pig and Its Release During Parturition

Parturition in the Guinea-Pig; Plasma Levels of Steroid Hormones, Steroid-Binding Proteins, and Oxytocin, and the Effect of Corticosteroids, Prostaglandins and Adrenocorticotrophin

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