FSH and LH activity of PMSG from mares at different stages of gestation

Blood was collected from each of four mares at approximately 60, 90 and 120 days of pregnancy. Pregnant mare serum gonadotrophin (PMSG) was prepared in a relatively impure form from each serum sample. Biological activities of FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone) were determined for each sample. FSH activity was greatest at 60 days of gestation and was reduced by day 90; this reduction persisted through day 120. LH activity was highly variable among mares at 60 and 120 days, and variability and mean values were lowest at 90 days. The mean ratio of FSH to LH was greatest at 90 days. The mean ratio of FSH to LH was greatest at 90 days and somewhat lower at both 60 and 120 days. The results suggest that the composition and biological activity of PMSG, as prepared and assayed by these procedures, may vary during gestation as well as among mares.     

Changes in pulsatile secretion patterns of LH, FSH, progesterone, androstenedione and oestradiol in cows after superovulation with PMSG

Six heifers were injected i.m. with 2500 i.u. PMSG followed by 15 mg prostaglandin 48 h later. Serial blood samples were collected through a catheter in the caudal vena cava every 10 min for 8 h on Day 10 (7 h after PMSG administration), during luteal regression (7 h after prostaglandin administration) and on the day thereafter. Four normally cyclic heifers served as a control group. Concentrations of progesterone, androstenedione, oestradiol, LH, FSH, and PMSG in the vena cava samples were measured and the frequency and amplitudes of episodic pulses of all hormones were estimated except for PMSG. Ovaries were collected by ovariectomy at 50 h after onset of luteal regression to determine the number of preovulatory follicles (non-atretic follicles greater than or equal to 10 mm). Stimulation of follicular growth by administration of PMSG resulted in the following effects on the secretion of steroids and endogenous gonadotrophins. (1) There were no alterations in progesterone concentration and the amplitude and frequency of episodic pulses. Mean (+/- s.e.m.) concentrations were 54.1 +/- 5.8, 19.1 +/- 3.1 and 3.4 +/- 0.9 nmol/l on Day 10 (L), during luteal regression (LR) and on the day thereafter (F) respectively. (2) There were no alterations in the episodic secretion patterns of androstenedione. Mean concentrations were 0.20 +/- 0.02, 0.15 +/- 0.02 and 0.11 +/- 0.02 nmol/l for the L, LR and F periods respectively. (3) There was an increase in oestradiol concentration from 17.1 +/- 3.0 pmol/l during the L period to 233.7 +/- 86.4 pmol/l during the F period. Pulse amplitude was enhanced compared to corresponding periods in control animals whereas pulse frequency remained the same. The oestradiol concentration was significantly correlated with the number of preovulatory follicles (r = 0.82, P less than 0.05). (4) There was a suppression of the frequency of episodic LH pulses (/8 h) during the LR (3.2 +/- 0.7) and F (4.3 +/- 0.4) periods compared to corresponding periods in control heifers (9.5 +/- 0.9 and 7.0 +/- 1.5 respectively). The preovulatory LH peak occurred earlier in 4 of 6 treated heifers. (5) There was a suppression of FSH concentrations, pulse amplitude and frequency during the LR and F (17.4 +/- 0.9 mg/l, 4.7 +/- 0.8 microgram/l and 7.5 +/- 0.4 pulses/8 h) periods compared to the corresponding F-period values (35.6 +/- 6.2 mg/l, 9.8 +/- 1.6 micrograms/l and 9.3 +/- 0.3 pulses/8 h) in control heifers.(ABSTRACT TRUNCATED AT 400 WORDS)     

FSH and LH concentrations in periparturient mares.

The influence of the ovaries and presence of a foal on periparturient concentrations of FSH and LH were studied in 19 Pony mares. In intact and ovariectomized mares, mean concentrations of FSH fluctuated between 1.1and 9.9 ng/ml on Days -14 to-1 before parturition (Day 0). A surge of FSH occurred in all mares in association with parturition. From Days 1 to 10, the high levels of FSH gradually decreased in the intact group to the minimal concentrations that occur during oestrus, but remained elevated in the ovariectomized mares. There were no significant pre-partum changes in LH in either type of mare. Post-partum changes in LH concentrations increased at a similar rate in ovariectomized and intact mares. The presence of a foal significantly lengthened the interval to first oestrus, depressed LH levels on Days 6--10 and decreased the FSH concentrations as averaged over the 10 days before the first ovulation after parturition.     

Effect of LH, FSH, LH + FSH and homoplastic pituitary extract on developing testis and epididymis of pigeon Columba livia

Ovine LH is needed for differentiation of juvenile Leydig cells and for their maintenance and steroidogenic potential, while FSH is necessary for Sertoli cell activity and spermatogonial multiplication suggesting that LH is steroidogenic hormone and FSH is gametogenic in the developing pigeon, C. livia. Homoplastic pituitary extract is more potent than ovine LH + FSH in stimulating gametogenic and endocrine components of the developing testis.     

Changes in rat ovaries of specific binding for LH, FSH and prolactin during the oestrous cycle and pregnancy.

In cyclic rats, the highest ovarian specific binding for LH was 6-0+/- 2-2% inpro-oestrus. During pregnancy, the specific binding of 125I-labelled bovine LH by rat ovaries increased gradually and reached a maximum of 24-1+/-4-9% between Days 14 and 18 of gestation; a slight decrease in binding was observed at Day 20 of pregnancy. Ovarian specific binding for FSH was also highest in pro-oestrus (8-9+/-2-1%), decreasing to about 50% in oestrus and metoestrus, but staying relatively constant during pregnancy. For prolactin, the specific binding in rat ovaries was highest (7-1+/-1-6%) in pro-oestrus, quite high in metoestrus and dioestrus and low in oestrus. Specific binding increased gradually only after Day 14 of pregnancy. Serum concentrations of rat LH, FSH and prolactin at different stages of the oestrous cycle and during pregnancy were determined by radioimmunoassays, and no obvious correlation was observed between levels of circulating hormones and the specific binding of these hormones in ovarian tissues. Affinity constants (Ka) for the hormones were very similar between ovaries from pro-oestrous rats and late-pregnant rats, being 0-31 X 10(9) M-1 for LH, 0-65 X 10(10)M-1 for FSH, and 1-14 X 10(10)M-1 for prolactin. Increases in specific binding for different hormones were due to increases of total binding sites in the ovary under different physiological states.     

On the correlation between FSH, LH and prolactin serum levels.

In 188 males FSH, LH, and prolactin serum levels determined from a single blood sample were found to be closely correlated. No correlation appeared to testosterone levels. The same correlation is observed, if serum levels of FSH, LH, and prolactin are measured after stimulation with LH-RH and TRH. In order to explain the close correlation, in five young men hormone levels were measured at 2-min-intervals over a period of 2 hours. Peaks of prolactin often correspond to those of FSH and LH, and a statistical correlation was found in two cases between FSH and prolactin. Results suggest a common releasing mechanism, which is superposed to the main mediating mechanism.     

Binding of LH and FSH to porcine granulosa cells during follicular maturation.

The uptake of 125I-labelled LH by equal numbers of granulosa cells from small, medium or large follicles was greater by cells from large follicles. In contrast, granulosa cells obtained from small follicles bound much more 125I-labelled FSH per cell than did cells obtained from medium and large follicles. Competition studies with unlabelled hormones indicated that porcine granulosa cells have specific receptors for LH and FSH. The addition of diethylstilboestrol enhanced the binding of 125I-labelled LH and inhibited the binding of 125I-labelled FSH to granulosa cells harvested from small and medium-sized follicles, but had no effect on those from large follicles.     

The use of FSH and GnRH as alternative compounds to PMSG for springtime breeding of ewes

During early springtime, ewes were treated with a single injection of PMSG (500 IU) administered at the time of progesterone sponge withdrawal (Group I) or four, twice daily injections of FSH (2 mg each) administered from twelve hours before, to 24 hours after sponge withdrawal (Group II). One hundred mug of GnRH was administered 36 hours after sponge withdrawal in Group II. The two groups were compared with respect to estrous display, conception rate and other reproductive parameters. There were no significant differences (p>.05) between the two treatment group in any of the reproductive parameters measured. The occurrence of estrus during the first 96 hours after synchronization was low (X = 45% of all treated ewes). Conception of all treated ewes during this estrous period was also low (X = 32% of all treated ewes). The potential use of FSH and GnRH in estrous synchronization regimes was discussed. Possible reasons for the poor estrous and conception rates in present experiment were also considered.     

Superovulatory response of Murciana goats to treatments based on PMSG/Anti-PMSG or combined FSH/PMSG administration

Superovulation in goats is frequently restricted by the cost of gonadotropin or the handling requirements. In this situation PMSG has the advantage of a lower cost and single dose protocol, but the variability of response obtained restricts its use. Thus, 2 alternative treatments with the advantages of PMSG were tested. In Experiment 1, we compared the ovulatory response of does treated with PMSG in combination or not with anti-PMSG antibodies at the onset of estrus, during season and out of season. In Experiment 2, we explored the effect of a partial substitution of FSH by PMSG at the end of treatment, comparing this treatment with a standard FSH protocol. Our results showed a significant (P < 0.01) seasonal effect on the incidence of corpora lutea (CL) regression in both experiments. The mean of viable embryos collected from does treated with anti-PMSG antibodies (mean = 5.75) was significantly higher than in the control PMSG-treated group (mean = 2.74) during spring (P < 0.05). Response during the fall was significantly lower regardless of treatment, and administration of antibody did not provide any significant improvement in superovulatory response (2.14 vs 1.77). In Experiment 2, the partial substitution of 3 doses of FSH by a single administration of PMSG did not reduce the number of CL or viable embryos, and no seasonal differences were observed, confirming that FSH provides a less variable response. From our results, it can be concluded that the use of PMSG antibodies for super-ovulating goats is an efficacious treatment which increases the number of viable embryos collected. However, partial replacement of FSH with PMSG at the end of treatment also did not compromise the number of embryos collected. Both approaches can be considered a valid alternative to treatments based on FSH.     

LH and FSH response of Holstein heifers to fertirelin acetate, gonadorelin and buserelin

This study was conducted to describe the changes in serum LH and FSH concentrations in Holstein heifers following intramuscular (i.m.) injection of various dosages of fertirelin acetate and other commerically available GnRH products at their labeled dosages. The design was an incomplete Latin-square which gave nine replicates of each treatment. Treatments administered on Days 8 to 16 of the estrous cycle consisted of saline; 25, 50, 100 or 200 mug fertirelin acetate; 100, 250 or 500 mug gonadorelin; and 10 or 20 mug buserelin. Blood samples were collected via jugular catheters from 1 h before to 8 h after each injection. Log (Base 2) area under the LH and FSH curves (log AUC) were used to evaluate response to fertirelin acetate dosages and to determine difference (LSD: 0.05) and bioequivalence (alpha = 0.05) between the various dosages of GnRH products tested. Significant quadratic dose response relationships were detected for the LH and FSH log AUC data. Plots of the LH log AUC but not the FSH log AUC data suggested that a response plateau was being approached at the higher dosages of fertirelin acetate. Bioequivalence (alpha = 0.05) was based on the assumption that two means are equivalent if they differ by no more than 20% of the reference log AUC mean. Using these criteria fertirelin acetate is 2.5 to 10 times more potent than gonadorelin, whereas buserelin is approximately 10 to 20 times more potent than fertirelin acetate in the bovine for LH and FSH release.