Intrafollicular and systemic serotonin,oestradiol and progesterone concentrations in cycling mares

The hypothesis that a local serotonergic network might also exist in the follicle of mares remains poorly documented, with exception for humans and laboratory species. For this reason, the aim of the present study was to clarify this possibility, investigating intrafollicular serotonin concentrations of the cycling mare at ovulation time. Sixty ovaries collected from 30 clinically healthy mares of slaughterhouse meat production with clinically normal reproductive tracts after slaughtering were evaluated. Blood samples were taken prior to sacrifice. Follicles were classified in three categories in relation to size, as small (20–30 mm), medium (31–40 mm) and large (>41 mm), and the follicular fluid samples were extracted from each follicle. Intrafollicular and systemic serotonin (5‐HT), oestradiol‐17β (E₂) and progesterone (P₄) were determined by means of enzyme‐linked immunosorbent assay and RIA, respectively. Intrafollicular 5‐HT, E₂ and P₄ concentrations were higher than systemic ones (p < .05). 5‐HT concentrations increased in larger compared to medium follicles, without differences compared to small size follicles (p < .05). 5‐HT and E₂ (r = .79) and 5‐HT and P₄ (r = .79; p < .05) were positively correlated. 5‐HT and P₄ concentrations in follicular fluid increased progressively with the increase in follicular size (p < .05). Follicle diameter and E₂ (r = .85) and P₄ (r = .68) were correlated (p < .05). Since serotonin interacts with steroids, its role on steroidogenesis during growth of the dominant follicle may be suggested.     

Periovulatory changes in peripheral plasma progesterone and estrogen concentrations in the mare.

Concentrations of progesterone and estrogen were measured in peripheral blood plasma samples from mares around the time of ovulation. Samples were collected every 2 hours from 36 hours before, to 26 hours after, ovulation and assayed by radioimmunoassay. Progesterone concentrations were between 60 and 100 pg/ml for the period 24 hours before ovulation through 8 hours after ovulation. By 10 hours after ovulation, concentrations increased to 140 pg/ml and, by 26 hours after ovulation, reached 346 pg/ml. Plasma estrogen concentrations did not change significantly throughout the same period.     

The effects of duration and concentration of plasma progesterone on the fertility of post-partum cows treated with pregnant mare serum gonadotrophin and intravaginal progesterone

The effects of duration of insertion of progesterone releasing devices (PRIDs) on the concentrations of plasma progesterone (plasma P4) and the relationship of these with fertility were examined respectively in ovariectomised and intact Bos taurus cattle. In experiment 1, ovariectomised cows (n = 14) were treated with PRIDs to produce high and low plasma P4 for 7 or 14 days giving 4 treatment groups designated H7, H14, L7 or L14. Mean plasma P4 in the H14 and L14 groups were 6.6 and 6.0 ng/ml respectively, during the first week and 5.4 and 3.8 ng/ml respectively, during the second. Mean plasma P4 of 6.3 and 4.2 ng/ml were observed in H7 and L7. In experiment 2, suckled cows (n = 171) received the same PRID treatments as cows in experiment 1, plus either 375 or 750 iu pregnant mare serum gonadotrophin, and subsequent calving rates were recorded. These were significantly lower after L7 than the other treatments (12% v 38%, P less than 0.025). These results showed that fertility after oestrus was closely related to plasma P4 observed before oestrus and indicated that treatment with progesterone for as little as 1 week can produce normal fertility providing plasma P4 attain a critical threshold during treatment.     

Uterine activity in cows during the oestrous cycle, after ovariectomy and following exogenous oestradiol and progesterone

Uterine activity was monitored in three, 2-year-old nulliparous Ayrshire heifers using intrauterine balloon-tipped catheters and pressure transducers during the oestrous cycle, after ovariectomy and following the intravenous infusion of progesterone and oestradiol-17 beta. During the oestrous cycle uterine activity, as measured by the frequency and amplitude of contractions, was greatest around oestrus and declined during the luteal phase of the cycle; there was a close correlation with peripheral progesterone concentrations. In two animals after bilateral ovariectomy spontaneous uterine activity persisted, whilst in the third animal the uterus was quiescent. In the first two heifers intravenous progesterone infusions reduced the spontaneous uterine activity, eventually completely abolishing it. There was evidence of a dose response effect at the two infusion rates. Oestradiol benzoate infusions initially inhibited spontaneous uterine activity before stimulating contractions with some evidence of a dose relationship. As demonstrated in normal cyclical and steroid-infused animals, uterine activity appears to be under the influence of both hormones although the influence of progesterone is greater.     

Changes in oestrogen,progesterone and epidermal growth factor receptor concentrations and affinities during the oestrous cycle in the normal mammary gland and uterus of dogs

Changes in the concentrations and affinities of receptors for oestrogen (ER), progesterone (PR) and epidermal growth factor (EGF-R) were studied in mammary glands of healthy bitches with regard to age, the location in the mammary chain and the stage of the oestrous cycle. Uterus was used as the reference tissue for the evaluation of steroid receptors. Mammary and uterine samples from 7 healthy bitches were taken at five stages of the oestrous cycle in such a way that all the locations in the mammary chain were represented at each stage of the cycle (10 samples/dog). ER, PR and EGF-R were detected by biochemical assays using increasing concentrations of tritiated (steroids) or iodinated (EGF) ligands. A significant direct correlation was found between the ER and PR concentrations for mammary and uterine samples. No significant correlation was found between the steroid receptors and EGF-R concentrations. Mammary ER concentrations were significantly higher in bitches of 5 years of age or older than in younger ones; in posterior glands (4th and 5th pairs) than in anterior glands; and in the mid-luteal phase. Mammary PR did not vary significantly with age or location but was significantly lower in the early luteal phase than in other phases. A similar decrease in PR concentrations was observed in the uterus during the early luteal phase and uterine ER and PR concentrations were very low in the mid-luteal phase. Mammary EGF-R were not significantly higher in the early or mid-luteal phase than in pro-oestrus or anoestrus.The differences observed between the uterine and mammary steroid receptor concentrations during the oestrous cycle could be due to different mechanisms for regulating steroid receptor expression in the two tissues. Mammary EGF-R concentrations may be linked, as in other species, to cellular proliferation and/or to the serum progesterone concentrations.Abbreviations BSA bovine serum albumin - EGF epidermal growth factor - EGF-R receptor for epidermal growth factor - ER oestrogen receptor - K _d dissociation constant - LH luteinizing hormone - p probability of error - PR progesterone receptor     

The effects of progesterone and oestrogen treatment in heifers on oestrous cycle control and plasma progesterone levels

Data are presented on the effects of a short-term progesterone treatment for oestrous cycle control in cattle. Progesterone was administered by intravaginal sponge pessaries inserted for a 10-day period. Progesterone pessaries alone did not affect oestrous cycle length or corpus luteum function at either early (day 2) or midluteal (day 12) cycle stages. However, when progesterone (250 mg) and oestradiol benzoate (7-5 mg) were given intramuscularly on the day of pessary insertion corpus luteum development was inhibited in animals treated at day 2 and was regressed in animals at day 12. This combined oestrogen-progesterone treatment efficiently controlled oestrous cycle length.     

Tissue concentrations of eosinophilia in the bovine oviduct and uterus of different stages of the oestrous cycle

Numbers of eosinophils in the bovine oviduct and uterus were determined during the oestrous cycle. The eosinophil numbers in the oviduct (ampulla and isthmus) and horn of the uterus during oestrus were significantly higher than during dioestrus. The number of eosinophils in the uterine cervix was lower than in the uterine horn for all stages of the oestrous cycle. In the oviduct, eosinophils accumulated in the lamina propria of the tunica mucosa, in the tunica muscularis and in the connective tissue of the tunica serosa. In the uterus, they were concentrated mainly in the upper parts of the stroma in the endometrium. Degranulation of eosinophils was observed during oestrus when they increased in number in the oviduct and uterus.     

Maternal and umbilical venous plasma lipid concentrations at delivery in the mare

The concentrations and fatty acid composition of the plasma free fatty acid, triacylglycerol and phospholipid fractions were determined in maternal and umbilical cord vein blood samples taken at delivery from 17 mares. Maternal and umbilical vein plasma free fatty acid concentrations were of a similar order and a positive correlation was found between the two levels suggesting that the equine placenta is permeable to fatty acid. Substantial amounts of the essential fatty acids and their longer chain derivatives were seen in both umbilical vein plasma free fatty acid and phospholipid fractions supporting this view. Certain long chain polyunsaturated derivatives of the essential fatty acids found in the umbilical venous plasma phospholipid fraction were not seen in the maternal circulating lipids. The precursor fatty acids were readily available to both foetal and placental tissues and therefore must have been elongated and incorporated into phospholipid by either or both. Very small amounts of the essential fatty acids were found in adipose stores in the newborn foal and virtually no fat stores at all in the newborn foal liver.     

Expression of oestrogen receptor,androgen receptor and progesterone nuclear receptor in sheep uterus during the oestrous cycle

Oestrogen, androgen and progesterone are involved in the regulation of uterine physiological functions, with the participation of the following proteins: oestrogen receptor (ER), androgen receptor (AR) and progesterone nuclear receptor (PGR). In this study, we used immunohistochemistry to detect the localization of ERα, ERβ, AR and PGR in sheep uterus. Additionally, we used real‐time polymerase chain reaction (RT‐qPCR) and Western blot technique to analyse their expression profiles at different stages of sheep oestrous cycle in the endometrium and myometrium. Immunohistochemical analysis showed that ERα, ERβ, AR and PGR were present in sheep uterus in oestrus, mainly in the uterine luminal epithelium, stroma, gland and myometrium. Real‐time polymerase chain reaction results showed that in the endometrium, ERα expression level was highest in oestrus. ERβ and PGR, instead, were highly expressed in pro‐oestrus. In the myometrium, ERα was highly expressed in both oestrus and pro‐oestrus, and ERβ was highly expressed in oestrus and dioestrus. Progesterone nuclear receptor expression was highest in oestrus, followed by metoestrus. In the endometrium, both receptors ERα and ERβ were abundant in pro‐oestrus, while the maximum AR protein content was found in oestrus. At this stage of the oestrous cycle, PGR protein concentration in the myometrium was significantly lower than those observed in other stages. These results suggest that these receptors are important for sheep reproductive function, as their expression at mRNA and protein levels exhibits particular time‐ and tissue‐specific profiles along the oestrous cycle.     

Varices with thrombosis in the cervix and uterus of a mare.

Cervical and uterine varices with thrombosis were observed at the necropsy of a virgin 16-year-old Peruvian Paso that had previous episodes of hemorrhage from the uterus. Practitioners and pathologists should be alert to the possibility of ruptured varices in mares with hemorrhage into the uterus or from the vulva.     

Histological changes in the vaginal mucosa of the cow during the oestrous cycle, after ovariectomy and following exogenous oestradiol benzoate and progesterone treatment

The histological structure of the anterior vaginal mucosa was studied using sequential biopsies in five normal cyclical Friesian cows and in four of the same cows after ovariectomy and exogenous progesterone and oestradiol benzoate. During oestrus the epithelium comprised a single layer of tall columnar, highly active, mucus-secreting cells, whereas during the luteal phase of the cycle it comprised several layers of low columnar, cuboidal or flattened epithelial cells. Exogenous oestradiol benzoate and progesterone administered separately produced little change in the low columnar and cuboidal epithelium observed after ovariectomy.     

The uterus and early pregnancy failure in the mare

The environment the equine conceptus finds itself in when it arrives in the uterus some 6 days after ovulation will determine if it will thrive or die. The uterus will be its home for approximately the next 11 months and as such it needs to both coordinate the growth of the placenta and ensure there is enough nourishment passing to this organ for the fetus to develop normally. The trophoblast, endometrium, maternal ovaries and, later in pregnancy, the fetal gonads, all play roles in the hormonal changes that orchestrate these events. Although failures of these processes later in pregnancy can have catastrophic effects for the fetus, it is in early gestation that the foundations for a successful pregnancy are laid. This paper therefore concentrates on some of the noninfectious influences the uterus may have on survival of the young conceptus.