Search Results
You are looking at 1 - 5 of 5 items for
- Author: M. Hamon x
- Refine by access: All content x
Search for other papers by M. H. Hamon in
Google Scholar
PubMed
Search for other papers by R. B. Heap in
Google Scholar
PubMed
Summary. Steroid hormone concentrations have been measured in the peripheral plasma of 3 Barbary sheep over 3 breeding seasons. During pregnancy mean progesterone values rose initially and after a small decline between Days 30 and 50, increased again and remained between 17 and 28 nmol/l until the last 2 days of pregnancy. Oestradiol-17β reached a peak of about 300pmol/l during mid-pregnancy, increasing to over 400 pmol/l in the last 5 days of pregnancy. Oestrone sulphate began to increase in concentration from about Day 40 of pregnancy and reached a peak of about 19 nmol/l by Day 120. Following a slight decrease from Day 130, there was a further rise in values just before parturition. Values for these steroids in the Barbary sheep studied were between those expected for domestic sheep and goats.
Keywords: progesterone; oestrogen; pregnancy; Barbary sheep
Search for other papers by R. B. Heap in
Google Scholar
PubMed
Search for other papers by I. R. Fleet in
Google Scholar
PubMed
Search for other papers by M. Hamon in
Google Scholar
PubMed
Summary. [3H]Prostaglandin F-2α (PGF-2α) was infused into a uterine lymphatic vessel or a uterine vein for up to 1 h, or injected into the uterine lumen of anaesthetized non-pregnant sheep 7–15 days after oestrus. After an intraluminal injection, labelled PGF-2α was recovered in uterine lymph and peak radioactivity was reached 50 min after injection. [3H]PGF-2α infused at a constant rate into a uterine lymphatic vessel resulted in a maximum concentration of radioactivity in plasma which was 5·6- and 1·7-fold higher in the adjacent utero-ovarian and ovarian vein, respectively, than in carotid arterial plasma. Estimation of the amount of infusate transferred from a lymphatic into ovarian venous blood gave a value (0·4%) similar to that for transfer from a uterine vein (0·3%). Evidence for local transfer was substantiated by the presence of significantly higher concentrations of 3H-labelled compounds in the ovary and corpus luteum adjacent to the site of intra-lymphatic infusion compared with those in the opposite organs. The concentrations in the adjacent ovary and corpus luteum were significantly greater when an intra-lymphatic rather than intra-uterine vein infusion was adopted.
The results show that [3H]PGF-2α is transferred locally from uterine lymphatic vessels into the adjacent ovary, corpus luteum and ovarian vein.
Search for other papers by R. B. Heap in
Google Scholar
PubMed
Search for other papers by M. H. Hamon in
Google Scholar
PubMed
Search for other papers by W. R. Allen in
Google Scholar
PubMed
Summary. Aromatase distribution in membranes of preimplantation horse and donkey conceptuses was compared by measuring the incorporation of [3H]androstenedione into oestrone and oestradiol-17β. In the donkey conceptus, aromatase activity was similar in all the tissues examined (yolk sac, chorionic girdle and allantochorion), whereas in the horse it was generally lower and showed the relationship chorionic girdle > yolk sac > allantochorion. A higher proportion of labelled precursor was incorporated into oestradiol-17β by extra-embryonic tissues of the donkey compared with those of the horse. In contrast to previous results, aromatase in the chorionic girdle did not decline progressively before its migration into the endometrium on Day 36 to form the endometrial cups. The chorionic girdle of a donkey conceptus carried in the uterus of a mare failed to invade the surrogate horse endometrium and aromatase activity was still high in this tissue at Day 42. Aromatase distribution in 2 transferred donkey-in-horse conceptuses resembled that of the fetal, rather than the maternal, genotype indicating a lack of effect of the maternal environment.
Keywords: oestrogens; conceptus; embryo transfer; donkey
Search for other papers by R. A. Nowak in
Google Scholar
PubMed
Search for other papers by M.-W. Wang in
Google Scholar
PubMed
Search for other papers by M. H. Hamon in
Google Scholar
PubMed
Search for other papers by D. J. Lamb in
Google Scholar
PubMed
Search for other papers by D. W. Bullock in
Google Scholar
PubMed
Search for other papers by R. B. Heap in
Google Scholar
PubMed
Summary. Anti-progesterone monoclonal antibody, injected into mice 32 h after mating at a dose that blocks the establishment of pregnancy, produced a significant reduction in the concentration of progesterone in the ovary and uterus within 6 h after treatment. Uterine concentrations remained lower in treated compared with control animals for at least 24 h after injection. There was an associated transient increase in plasma LH and FSH concentrations, but there was no change in plasma prolactin values. The percentage of total progesterone in the circulation that was unbound was reduced after treatment, but the concentration of unbound progesterone was increased. Studies of antibody binding of steroid in the presence of uterine progesterone receptor protein showed that there was a stoichiometric relationship in the distribution of ligand between the two binders. The present findings suggest that the effects of passive immunization against progesterone are associated with perturbation of tissue concentrations of steroid in the target organ as a result of high antibody concentrations in the circulation.
Keywords: progesterone; immunization; pregnancy; uterus; ovary; mouse
Search for other papers by I. R. Fleet in
Google Scholar
PubMed
Search for other papers by A. J. Davis in
Google Scholar
PubMed
Search for other papers by J. A. Goode in
Google Scholar
PubMed
Search for other papers by M. Hamon in
Google Scholar
PubMed
Search for other papers by R. J. Collier in
Google Scholar
PubMed
Search for other papers by R. B. Heap in
Google Scholar
PubMed
Prostaglandin F2α (PGF2α)-induced release of ovarian oxytocin was investigated to determine whether the effect in vivo was local. [3H]PGF2α infused downstream into a single ovarian lymphatic was transferred into the adjacent ovarian vasculature (estimated transfer 1.1 and 1.7%, two experiments). When unlabelled PGF2α was infused in a similar manner (76 pmol min−1), there was a prompt eightfold increase in ovarian oxytocin release from the adjacent ovary containing a corpus luteum, but no effect on the opposite corpus luteum, showing that the effect was local. Instillation of 2% lignocaine into the ovarian vascular pedicle did not affect PGF2α-induced oxytocin release, supporting the idea that neural mechanisms are not involved. Repeated doses of PGF2α given close-arterially produced a successive reduction in oxytocin release. This effect was prevented by a prior infusion of insulin-like growth factor-I (IGF-I), which itself gave a small, but significant, increase in oxytocin release. The results show that PGF2α in ovarian lymphatics acts locally and directly to stimulate ovarian oxytocin secretion, that repeated exposure of the corpus luteum to pulses of PGF2α can result in tachyphylaxis, and that this latter effect can be ameliorated by IGF-I infused in vivo.
