Prostaglandin F-2 alpha is transferred from the uterus to the ovary in the sheep by lymphatic and blood vascular pathways

Contractile effect of PGF2alpha and PGE2 on isolated branches of uterine and ovarian artery in different days of estrous cycle and early pregnancy in pigs

The contractile effects of PGF2alpha (3 x 10(-6) to 10(-4) M) and PGE2 (10(-7) to 10(-5) M) were examined on isolated branches of ovarian artery (OA) and extramyometrial branches of uterine artery (UA) collected from pigs in the luteal (day 10-12) and follicular phase (day 17-20) of the estrous cycle, and during early pregnancy (day 10-12). Strong contraction was demonstrated in both arteries during all investigated periods in response to PGF2alpha, which was significantly higher (P < 0.01) than to PGE2, being negligible in the follicular phase. In UA, the effective dose of PGF2alpha (ED50) amounted 7.9 x 10(-6) M and 6.3 x 10(-6) M in the luteal and follicular phase, and 5.0 x 10(-6) M in early pregnancy. ED50 for PGE2 reached 5.0 x 10(-7) M in the luteal phase, and 4.1 x 10(-7) M in early pregnancy. For both prostaglandins, the contraction was much stronger (P < 0.01) in OA than in UA branches. In OA, the ED50 for PGF2alpha was 1.2 x 10(-5) M in the luteal phase and was significantly higher (P < 0.05) than in the follicular phase (3.1 x 10(-6) M) and early pregnancy (2.7 x 10(-6) M). ED50 for PGE2 amounted 7.3 x 10(-7) M in the luteal phase and 1.7 x 10(-7) M in early pregnancy. Studies showed the influence of the estrous cycle and early pregnancy on OA branches sensitivity to the contractile effect of PGF2alpha and the lack of this effect on UA branches, and the influence of the estrous cycle on UA and OA branch contraction in response to PGE2.

The role of the endometrium in endocrine regulation of the animal oestrous cycle

A critical analysis of the results of research in the function of the endometrium was carried out and a view point presented. The role of the endometrium in endocrine regulation of the oestrus cycle can be summarized as follows: 1. The transfer of prostaglandin F(2alpha) (PGF(2alpha)) from the uterus to an ovary, which causes luteolysis, occurs mainly via the lymphatic pathways. 2. The system of retrograde transfer of PGs enables PGF(2alpha) and PGE(2) to reach the myometrium and endometrium with arterial blood at high concentration. In the luteal phase, PGF(2alpha), together with the increasing concentration of progesterone, constricts the arterial vessels of the uterus; in the follicular phase and in early pregnancy, PGE(2) together with oestrogen and embryonic signals, relaxes the arterial vessels. In addition, this system protects the corpus luteum from premature luteolysis during the cycle and luteolysis during early pregnancy. 3. In days 10-12 of the cycle, the blood flow in the uterus decreases by 60-70% in pigs and around 90% in sheep. This causes ischaemia and local hypoxia confirmed by the presence of hypoxia inducible factor and thus remodelling of the endometrium commences. 4. The pulsatile elevations in PGF(2alpha) concentration occurring in the blood flowing out of the uterus during the period of luteolysis and the next few days, do not result from increased PGF(2alpha) synthesis as suggested in numerous studies. They are the effect of excretion of PGF(2alpha) and its metabolites together with lymph and venous blood and tissue fluids in which prostaglandin accumulates.

Intravascular pressure and diameter profile of the utero-ovarian resistance artery network: estrous cycle-dependent modulation of resistance artery tone

Blood flow to the ovary varies dramatically in both magnitude and distribution throughout the estrous cycle to meet the hormonal and metabolic demands of the ovarian parenchyma as it cyclically develops and regresses. Several vascular components appear to be critical to vascular regulation of the ovary. As a first step in resolving the role of the resistance arteries and their paired veins in regulating ovarian blood flow and transvascular exchange, we characterized the architecture and intravascular pressure profile of the utero-ovarian resistance artery network in an in vivo preparation of the ovary of the anesthetized Golden hamster. We also investigated estrous cycle-dependent changes in resistance artery tone. The right ovary and the cranial aspect of the uterus in 26 female hamsters were exposed for microcirculatory observations. Estrous-cycle phase was determined in each animal before experimentation. The utero-ovarian vascular architecture was determined and resistance artery diameters were measured in each animal by video microscopy. Servo-null intravascular pressure measurements were made throughout the uteroovarian arterial network in 11 of the animals. Architectural data showed a complex anastomotic network jointly supplying the uterus and ovary. Resistance arteries showed a high degree of coiling and close apposition to veins, maximizing countercurrent-exchange capabilities. Arterial pressure dropped below 60% of systemic arterial pressure before the arteries entered the ovary. Both the ovarian artery and the uterine artery, which jointly feed the ovary, showed cycle day-dependent changes in diameter. Arterial diameters were smallest on the day following ovulation, during the brief luteal phase of the hamster. The data show that resistance arteries comprise a critical part of a complex network designed for intimate local communication and control and suggest that these arteries may play an important role in regulating ovarian blood flow in an estrous cycle-specific manner.

Retrograde and local destination transfer of uterine prostaglandin E2 in early pregnant sow and its physiological consequences

The local destination transfer of prostaglandin E2 (PGE2) from the uterine lymph to arterial blood supplying the ovary and its retrograde transfer to arterial blood supplying the uterine horn and the effect of additional delivery of PGE2 into the ovary on the secretion of steroid hormones was studied in early pregnant gilts. The injection of PGE2 under the perimetrium caused an increase (P<0.001) in PGE2 concentration in both uterine venous effluent and ovarian and uterine arterial blood. The infusion of PGE2 into the ovarian artery increased the concentration of progesterone in ovarian venous blood on day 13 of pregnancy during (P<0.05) and after (P<0.001) infusion, and on day 14 of pregnancy after infusion (P<0.01). In conclusion, local destination transfer of PGE2 from uterine lymph and venous blood to the ovary may affect luteal function, and retrograde transfer of PGE2 to the arterial blood supplying the uterus may contribute to the prevention of regressive changes of the endometrium in early pregnant gilts.

Local transfer of prostaglandin E2into the ovary and its retrograde transfer into the uterus in early pregnant sows

This study was designed to establish (a) whether prostaglandin E2 (PGE2) can reach the ovary and oviduct by a local pathway and what is the contribution of lymphatic vessels to this transfer, and (b) whether PGE2 can permeate from venous and lymphatic vessels of the mesometrium to arterial blood and be delivered to the uterine horn during maternal recognition of pregnancy in gilts. The reproductive tract was excised from gilts (n = 10) on day 14 after mating. The uterine horn was isolated with the ovary and broad ligament and perfused with warmed and oxygenated autologous blood. A total dose of 5.5 x 10(7) disintegrations per min (d.p.m.) (49 ng) [3H]PGE2 was infused into the small branches of the uterine vein on the broad ligament or into the lymphatic vessels. Frequent blood samples were collected from the branch of the uterine artery and from the venous effluent. Tissue samples were collected from the uterine horn, the ovary and the broad ligament. The concentration of [3H]PGE2 was significantly higher in the ovary (P < 0.001), oviduct (P < 0.01), endometrium (P < 0.01), myometrium (P < 0.001) and mesometrium (P < 0.001) after infusion of [3H]PGE2 into lymphatic vessels than into the branches of the uterine vein. In contrast, the concentration of [3H]PGE2 was significantly higher in arterial blood supplying the uterine horn (P < 0.01) and in the venous effluent (P < 0.001) after infusion of [3H]PGE2 into the branches of the uterine vein than into lymphatic vessels. These results demonstrated local transfer of [3H]PGE2 into the ovary, oviduct and uterine horn from lymphatic and venous vessels of the mesometrium. However, the efficiency of this transfer was considerably higher after infusion into lymphatic vessels than into branches of the ovarian vein. We conclude that the lymphatic pathway is a fundamental mechanism in the local transfer of PGE2 from the uterus to the ovary and oviduct during early pregnancy in the pig.

Counter-current transfer in reproductive biology

Heat and substances, including gases, steroids and peptide hormones, can pass from venous blood, interstitial fluid and lymph to the arterial blood; the process is called local counter-current transfer. It has been found in various reproductive organs in many animal species and in man: from the testis to the testis and epididymis; from the ovary to the ovary, tube and tubal corner of the uterus; from the tube and uterus to the ovary; from vagina to uterus; and even between brain blood vessels. Local transfer within the ovary has also been found. Local cooling that creates temperature gradients between organs or within an organ is one aspect of the transfer. Physiologically, the transfer also facilitates local feedback regulation of organ function in a process situated between general distribution of hormones through the systemic circulation and paracrine regulation. Counter-current transfer of drugs after local application opens up new possibilities for treatment.

The oestrous cycle and early pregnancy – a new concept of local endocrine regulation

Facts discovered in recent decades have compelled us to revise long-established views on the physiological regulation of cyclic adjustments to the reproductive system in preparation for pregnancy in females. Evidence has been presented to show that changes in the uterine blood supply induced by the oestrogen/progesterone ratio in the blood and cytokines are important in the regulation of the secretory function of the endometrium. Progressive reduction in uterine blood flow during the luteal phase of the oestrous cycle causes regressive changes in endometrial cells and release of prostaglandin (PG) F(2 alpha), resulting in initiation of luteolysis. Retrograde transfer of PGF(2 alpha) in the area of the mesometrium vasculature is an important element in the mechanism protecting the corpora lutea against luteolysis before day 12 of the porcine oestrous cycle and during early pregnancy and pseudopregnancy. Results of many studies presented in this review indicate that PGF(2 alpha) pulses in uterine venous blood during the follicular phase of the oestrous cycle may not be due to PGF(2 alpha) secretion by endometrial cells, but occur due to remodeling of the endometrium and pulsatile exretion of PGF(2 alpha) in accordance with rhythmic uterine contractions caused by oxytocin.

Morphological analysis of transportation pathways of microspheres after their introduction into the uterine horn cavity in cyclic pigs

Countercurrent transfer is thought to be one of the most important mechanisms involved in the transfer of substances between the uterus and oviduct. The present study was aimed at recognizing other putative transportation pathways from the uterine cavity through the oviduct onto the surface of and into internal ovarian structures. Microspheres (latex beads, 0.8 microm in diameter) were introduced into the uterine horn cavity of pigs, for 30 min, at various days of the estrous cycle. The transportation pathways of the beads were then analyzed by light and electron microscopy. The transport of microspheres through the oviduct canal into ovarian tissues took place on each day of the estrous cycle. The largest numbers of microspheres passed through the tunica albuginea to the corpora lutea. Some of microspheres also reached the surface of the uterine ligament through the oviduct canal, where they attained the lumen of blood and lymphatic vessels, mainly of the vascular subovarian (VSP) and paraovarian lymphatic plexus (PLP), via the lymphatic stomata pathway. Transport of microspheres also took place simultaneously through the uterine and oviduct walls and from particular organs through blood and lymphatic vessels. Although the present results do not exclude the participation of countercurrent transfer between venous, lymphatic, and arterial vessels, they provide morphological evidence for the presence of direct transportation pathways of substances, released into the uterine lumen, into ovarian tissues through the oviduct canal.

Pulsatile output of prostaglandin F(2alpha) does not increase around the time of luteolysis in the pregnant goat

Prostaglandin (PG) F(2alpha) secreted from the uterus is the luteolysin of the estrous cycle and is also believed to be responsible for luteolysis in the pregnant doe at term. We have reported that basal progesterone concentrations decrease before basal PGF(2alpha) concentrations increase, which is inconsistent with this view. In this study we investigated whether luteolysis is associated with increased frequency or amplitude of pulsatile PGF(2alpha) secretion in does over the last 2 wk of gestation. Progesterone concentrations decreased approximately 1 wk before parturition. There was no accompanying increase in PGF(2alpha) concentrations or pulse frequency, and those pulses that were observed were of lesser amplitude and duration than those that have been associated with luteolysis in cycling ewes. A small increase in PGF(2alpha) pulse frequency was identified during the 3 days before parturition, but this was not associated with any change in progesterone concentrations. The biological significance of these small changes in PGF(2alpha) pulse frequency is obscure, although the high concentration of this eicosanoid at labor may have been related to the final, precipitous decline in plasma progesterone concentrations. These findings do not support the notion that PGF(2alpha) is the principal luteolysin in the pregnant doe at term.

Ovine prostaglandin F2alpha receptor: steroid influence on steady-state levels of luteal mRNA

Expression of the receptor for prostaglandin F2alpha (PGF2alpha) is decreased in the ovine corpus luteum during regression and increased in early pregnancy. This study was designed to evaluate the influence of progesterone and/or 17beta-estradiol (E2) on this regulation. Circulating progesterone (functional regression) and luteal PGF receptor mRNA decreased (p < 0.05) within 8 h of PGF2alpha-induced luteal regression in midluteal phase (day 10; d 10) ewes; however, internucleosomal DNA fragmentation (structural regression) was not yet increased. Additionally, luteal PGF receptor mRNA and circulating progesterone were greater (p < 0.05) in pregnant than in nonpregnant ewes on d 14, but not on d 12. Twelve hours following injection of d 10 ewes with E2, steady-state levels of mRNA for PGF receptor were decreased (p < 0.05), although circulating progesterone and DNA laddering were unchanged. Conversely, luteal mRNA for PGF receptor was increased (p < 0.05) by E2 treatment in hysterectomized ewes. These results provide evidence that (1) luteal PGF receptor expression parallels circulating progesterone levels during functional regression and in early pregnancy, but (2) expression of PGF receptor can be dissociated from alterations in circulating progesterone by injection with E2. Additionally, decreased PGF receptor expression initiated by E2 is uterine-dependent, whereas the direct luteal effect (hysterectomized ewes) of E2 is a stimulation of PGF receptor expression. These results collectively support the belief that the apparent downregulation of PGF receptor during luteal regression is associated with uterine-derived PGF2alpha and its intracellular effects rather than with alterations in ovarian steroid production.

Luteolysis: a neuroendocrine-mediated event

In many nonprimate mammalian species, cyclical regression of the corpus luteum (luteolysis) is caused by the episodic pulsatile secretion of uterine PGF2alpha, which acts either locally on the corpus luteum by a countercurrent mechanism or, in some species, via the systemic circulation. Hysterectomy in these nonprimate species causes maintenance of the corpora lutea, whereas in primates, removal of the uterus does not influence the cyclical regression of the corpus luteum. In several nonprimate species, the episodic pattern of uterine PGF2alpha secretion appears to be controlled indirectly by the ovarian steroid hormones estradiol-17beta and progesterone. It is proposed that, toward the end of the luteal phase, loss of progesterone action occurs both centrally in the hypothalamus and in the uterus due to the catalytic reduction (downregulation) of progesterone receptors by progesterone. Loss of progesterone action may permit the return of estrogen action, both centrally in the hypothalamus and peripherally in the uterus. Return of central estrogen action appears to cause the hypothalamic oxytocin pulse generator to alter its frequency and produce a series of intermittent episodes of oxytocin secretion. In the uterus, returning estrogen action concomitantly upregulates endometrial oxytocin receptors. The interaction of neurohypophysial oxytocin with oxytocin receptors in the endometrium evokes the secretion of luteolytic pulses of uterine PGF2alpha. Thus the uterus can be regarded as a transducer that converts intermittent neural signals from the hypothalamus, in the form of episodic oxytocin secretion, into luteolytic pulses of uterine PGF2alpha. In ruminants, portions of a finite store of luteal oxytocin are released synchronously by uterine PGF2alpha pulses. Luteal oxytocin in ruminants may thus serve to amplify neural oxytocin signals that are transduced by the uterus into pulses of PGF2alpha. Whether such amplification of episodic PGF2alpha pulses by luteal oxytocin is a necessary requirement for luteolysis in ruminants remains to be determined. Recently, oxytocin has been reported to be produced by the endometrium and myometrium of the sow, mare, and rat. It is possible that uterine production of oxytocin may act as a supplemental source of oxytocin during luteolysis in these species. In primates, oxytocin and its receptor and PGF2alpha and its receptor have been identified in the corpus luteum and/or ovary. Therefore, it is possible that oxytocin signals of ovarian and/or neural origin may be transduced locally at the ovarian level, thus explaining why luteolysis and ovarian cyclicity can proceed in the absence of the uterus in primates. However, it remains to be established whether the intraovarian process of luteolysis is mediated by arachidonic acid and/or its metabolite PGF2alpha and whether the central oxytocin pulse generator identified in nonprimate species plays a mediatory role during luteolysis in primates. Regardless of the mechanism, intraovarian luteolysis in primates (progesterone withdrawal) appears to be the primary stimulus for the subsequent production of endometrial prostaglandins associated with menstruation. In contrast, luteolysis in nonprimate species appears to depend on the prior production of endometrial prostaglandins. In primates, uterine prostaglandin production may reflect a vestigial mechanism that has been retained during evolution from an earlier dependence on uterine prostaglandin production for luteolysis.

Cycle dependent variations in transfer of 133xenon from vagina to uterus in rats

The possible existence of an oestrus cycle dependent on local transfer of 133xenon from vagina to uterus was investigated in anaesthetized rats. 133Xenon in saline was infused into the vaginal lumen of rats in oestrous (n = 7) and dioestrous (n = 10). The uterus was removed 3 min after the infusion and the radioactivity in the organ counted, after which the remaining radioactivity in vagina was measured. The results showed that the radioactivity increased in all uteri compared with that of the background. The average transfer, expressed as per cent transfer, from vagina in the dioestrous group (5.5%) was significantly higher (P < 0.01, Mann-Whitney) than in the oestrous group (1.4%). The results suggest that the rate of transfer from vagina to uterus depended on the oestrous cycle. Vaginal treatment of women with progesterone for example, may similarly induce high local concentrations in the uterus. Empirically this is already used after in vitro fertilisation, it may also prevent progesterone induced migraine in menopausal women. The possible cycle dependent variations in the transfer in women should be evaluated.

Characterization and regulation of a mRNA encoding the prostaglandin F2alpha receptor in the rat ovary

The recent cloning of several cDNAs encoding prostaglandin (PG) receptors has paved the way for a more detailed investigation of the postulated regulatory role of prostaglandins in corpus luteum function. We have utilized the reverse transcription-polymerase chain reaction (RT-PCR) to isolate a mRNA encoding the ovarian PGF(2alpha) (FP) receptor, using oligonucleotides based on the recently cloned mouse cDNA as primers. The 5'-untranslated region of the rat ovarian mRNA was isolated following 5'-RACE (rapid amplification of cDNA ends). The isolated 1526 base-pair sequence, which spans the entire open reading frame, was found 100% identical in the protein coding region to a similar sequence isolated from a rat astrocyte cDNA library, but different in the first 32 nucleotides of the 5'-untranslated region, possibly due to tissue-specific splicing heterogeneity. Using ribonuclease protection assay, a quantitative analysis of FP receptor mRNA levels was performed in corpora lutea excised from adult pseudopregnant rats (Day 8) at different timepoints (0.5-48 h) following the in vivo s.c. regimen of a luteolytic dose of the FP receptor agonist cloprostenol (5 microg). Already 3 h after cloprostenol injection, FP receptor mRNA levels exhibited a pronounced increase to values 4.0-fold higher (P < 0.01) than before injection. At 7 h through 24 h, the amount of luteal FP receptor mRNA decreased, approaching preinjection levels, whereafter they were again 3.0-fold higher (P < 0.01) at 48 h than before injection. We conclude that following homologous stimulation of the FP receptor, abundance of this mRNA is tissue-specifically regulated in a dynamic pattern, suggestive of an important role for FP receptor-mediated action on gene expression during the demise of corpus luteum function.

Prostaglandin F2 alpha and E2 production into uterine lymph of pregnant and non-pregnant ewes

Uterine lymphatic cannulation was performed in pregnant and non-pregnant ewes so that serial lymph samples could be analysed for prostaglandins (PGs) on day 12 to 18 after oestrus. The production of PGF2 alpha into uterine lymph showed peaks of > 1000 pg/h between days 14 and 18 of the oestrous cycle. Such peaks were either absent or much reduced (< 900 pg/h) over the same period in four pregnant animals. PGE2 production into uterine lymph remained low (< 510 pg/h) both in the four non-pregnant animals in the later part of the oestrous cycle and in three of four pregnant animals between days 14 to 18 post mating.

The control of prostaglandin production by the endometrium in relation to luteolysis and menstruation

Oestradiol acting on a progesterone-primed uterus stimulates prostaglandin (PG) F2 alpha synthesis by the endometrium. In some species (notably the sheep, cow and goat) oxytocin released from the ovary also forms part of the physiological stimulus for increased endometrial PGF2 alpha production. The corpus luteum contains high concentrations (> 1 microgram/g tissue) of this peptide in these species. The intracellular mechanisms by which these three hormones control endometrial PGF2 alpha synthesis and release are far from clear. Oxytocin stimulates the synthesis of inositol phosphates and diacylglycerol in the endometrium of some species, but whether this pathway is involved in endometrial PGF2 alpha synthesis is still open to question. There is evidence that increased endometrial PGF2 alpha synthesis is dependent upon increased endometrial protein synthesis but, apart from the recorded effects of steroid hormones on the concentrations of phospholipase A2, prostaglandin H synthase and oxytocin receptors, it is not known what other endometrial proteins are involved. Some disorders of menstruation are associated with abnormal PG production by the endometrium, but the reasons for this abnormality are not clear. During early pregnancy an increase in PGF2 alpha synthesis by the endometrium is prevented, except in the pig where the PGF2 alpha produced is directed from the venous drainage to the uterine lumen. In those species in which endometrial PGF2 alpha synthesis is dependent upon oxytocin secreted by the ovary, the conceptus secretes an interferon-tau (previously named trophoblast protein-1) which prevents oestradiol and oxytocin acting on a progesterone-primed uterus from stimulating endometrial PGF2 alpha synthesis. The identities of the factors produced by the conceptus which prevent endometrial PGF2 alpha synthesis during early pregnancy in other species are not known, although it is clear that they are not interferons.

Ovarian and uterine lymphatic drainage in Australian flying-foxes (genus Pteropus, suborder Megachiroptera)

Ovarian lymphatics of flying-foxes were traced to determine if they could transport hormones directly from ovary to ipsilateral uterine horn, thereby stimulating the localised endometrial growth which is characteristic of these animals. Intra-ovarian injections of ink and serial histological sections did not reveal any such connection. All major ovarian lymphatics and those from the cranial tip of each uterine horn drain cranially, terminating in 1 or 2 lymph nodes lying caudal to the ipsilateral kidney. For much of their course, the major ovarian lymphatics run in the adventitia of the ovarian venous sinus. This sinus encloses the coiled ovarian artery, which provides the major blood supply to the cranial end of the ipsilateral uterine horn. Some fine ovarian lymphatics run in the adventitia of the coiled ovarian artery. The enclosure of the coiled ovarian artery by the ovarian venous drainage is thought to provide the main route for transfer of steroids from ovarian vein to ovarian artery and thence to ipsilateral uterine horn. The ovarian lymphatics described here do not bypass the vascular pathway but provide an additional route for counter- or cross-current transfer of ovarian steroids to the ovarian arterial supply to the uterus.

Rapid absorption and local redistribution of progesterone after vaginal application in gilts

Catheters were implanted in 6 anaesthetized gilts (3 animals in the follicular phase, 3 in the luteal phase) into a carotid artery and into the utero-ovarian vein and uterine artery on both sides. The uterine lumina were closed by a suture. Further, a catheter was inserted into the vagina after which the animals were allowed to recover. Tritiated progesterone was infused into vagina the following day during a 2 min period and simultaneous blood samples collected from the 5 catheters every 10 min for 2 h after which the animals were sacrificed. Tissue samples were obtained from the genital organs. The results showed a rapid absorption of progesterone from the vaginal lumen and a marked redistribution to the genital organs. The increased level of radioactivity in the plasma samples collected from the uterine arteries compared to the simultaneous samples from the carotid artery in 2 of the 3 animals in the luteal phase indicates the existence of a local redistribution system.

Chronic utero-ovarian vein catheterization with subsequent occlusion prolongs the estrous cycle and changes electromyographic activity in the myometrium of ewes

The objective of our study was to determine the effect of chronic utero-ovarian vein catheterization in ewes on estrous cycle length, plasma progesterone (P) concentration, and myometrial electromyographic activity. Cyclic ewes with inferior vena cava catheters were used as controls. Estrus was synchronized in ten ewes and 10 to 12 d following estrus, the ewes were anesthetized, fitted with myometrial electromyograph leads and with utero-ovarian vein (n = 5) or inferior vena cava (n = 5) catheters. After surgery, ewes returned to estrus as expected (16 to 18 d interestrus interval). The second cycle of four of five ewes with utero-ovarian vein catheters were prolonged (40 to 58 d). The inferior vena cava catheterized ewes had normal length second cycles. Plasma P concentrations reflected the estrous cycles: low (</= 0.01 ng/ml) at estrus and 2 to 3 ng/ml at midcycle. The inferior vena cava catheterized ewes had decreased plasma P concentrations after luteolysis (Days 13 to 14) while four of five utero-ovarian vein catheterized ewes maintained elevated plasma P concentrations for 20 to 58 d. Catheterization affected the myometrial electromyograph; short events (16 to 180 sec) were increased on Days 5 to 13 in utero-ovarian vein as compared with inferior vena cava catheterized ewes (P < 0.05); long events (180 to 900 sec) tended to decrease from Days 1 to 15 in utero-ovarian vein ewes, but this was not statistically significant (P > 0.05).

[3H]prostaglandin uptake in vivo by rabbit uterine tissues and blastocysts

Day-6 pregnant rabbits were anesthetized and subjected to a mid-ventral laparotomy. [3H] Prostaglandin F2alpha) (PGF2alpha) [3H]PGE2, [14C]Urea or [14C]Sucrose were instilled into the uterine lumen via the uterotubal junction. The amounts instilled/uterine horn were respectively 3.7 +/- 0.3, 3.5 +/- 0.3, 5.7 +/- 1.3 and 2.7 +/- 1.6 muCi in 20mul of buffer. Animals were killed at 1, 2, 9, 19 or 21 h after radioactive instillation, and the amounts of radioactivity in blastocysts, uterine tissue, peritoneal cavity washings and urine evaluated by liquid scintillation spectrometry. A gradient of radioactivity was observed from the uterotubal junction to the cervical end of the uterus. Large amounts of [3H]PG were found in the injected horn and associated blastocysts with a considerable crossover to the non-injected horn, but little in the associated blastocysts. Much of the blastocysts associated- [3H]PG remained unmetabolized. Large amounts of metabolized [3 H] were found in urine. [14C]Urea was taken up by uterine tissue in the injected horn, but there was little cross over to the non-injected horn. Urea was also found in urine. Much of the [14C]Sucrose remained in the injected horn, and little was recovered from the urine. It was found that at 9 h, but not at 19 h, after [3 H]PG instillation, the PG was localized at the site of the blastocysts in the injected but not in the contralateral horn. Significantly more [3H]PGF2alpha than [3H]PGE2 was localized in this situation. [14C]Urea was not localized at the site of the blastocysts in urea injected horns. (ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline phosphatase activities and progesterone concentrations in uterine flushings of dairy cows: side-effects and variations during oestrous cycle

After evisceration at an abattoir, both uterine horns of barren cows were flushed using 30 ml of Dulbecco's phosphate buffered saline (trial 1, 49 cows) or 10 ml sterile saline (0.9%, trial 2, 22 cows). Blood was collected from the animals' hearts (trial 2). Activities of alkaline phosphatase and progesterone concentrations (trial 2) were determined in uterine flushings and serum. In uterine flushings, both parameters exhibited a significant cyclic pattern, while in serum, only progesterone concentrations showed cyclic fluctuations. Alkaline phosphatase activities in uterine flushings taken ipsilateral to a corpus luteum were significantly higher than in materials obtained from the contralateral horn during dioestrus and prooestrus. A similar tendency was obvious for progesterone concentrations. All parameters but serum alkaline phosphatase activity were positively correlated with each other. The results suggest a close relationship between a progesterone secreting corpus luteum and metabolic as well as hormonal parameters evaluated in flushings of the ipsilaterally situated uterine horn. Transfer of progesterone via the blood vessels and lymphatics within the ligamentum latum uteri may be the cause of the between-side-effects detected.

Peripheral plasma levels of prostaglandin metabolites, cortisol and prolactin in women undergoing falope ring application and tubal cautery

The levels of 11-deoxy-13,14-dihydro-15-keto-11 beta, 16 xi-cyclo PGE2 (bicyclo PGEM), 13,14-dihydro-15-keto PGF 2 alpha (PGFM), cortisol and prolactin were measured by radioimmunoassays in five serial plasma samples collected from fourteen patients undergoing falope ring application and three patients undergoing tubal electrocautery. Bicyclo PGEM, PGFM and cortisol levels were unchanged regardless of the type of tubal occlusion procedure or the type of anesthesia administered (7 received general and 10 local anesthesia). Prolactin levels, on the other hand, markedly increased. The increase was greatest in women that received general anesthesia. The lack of change in bicyclo PGEM and PGFM in peripheral plasma would suggest a local transfer of PGs produced by injured tubal tissue to other parts of the tube and the uterus resulting in increased contractions and pelvic pain.