Plasma FSH Concentrations Research Articles

Effect of purified llama ovulation-inducing factor (OIF) on ovarian function in cattle

Two experiments were designed to determine the effect of purified ovulation inducing factor (OIF) on ovarian function in cattle. In Experiment 1, prepubertal heifers (n = 11 per group) were treated on Day 5 (Day 0 = day of follicular wave emergence) of the follicular wave with an intramuscular dose of saline (1 mL), GnRH (100 μg), or purified OIF (1 mg/100 kg body weight). Ovulation occurred in 9/11 heifers treated with GnRH, and 1/11 heifers in each of the OIF- and saline-treated groups (P < 0.05). Compared to saline-treated controls, OIF treatment was associated with a smaller dominant follicle diameter (P < 0.01), a rise in plasma FSH concentration (P < 0.1), and earlier emergence of the next follicular wave (P < 0.05). In Experiment 2, sexually mature heifers were given either GnRH or purified OIF on Days 3, 6 or 9 of the first follicular wave (i.e., early growing, early static, or late static phase of the dominant follicle; n = 5 per group per day), or were untreated (n = 10). In heifers treated with OIF on Day 6, the dominant follicle diameter profile tended to be smaller than in controls, and was associated with a rise (P < 0.05) in plasma FSH concentrations. A similar rise in FSH was detected after OIF treatment on Day 9. Compared to untreated controls, treatment with OIF and GnRH was associated with a larger CL diameter (Days 3 and 6 groups; P < 0.05) and a greater concentration of plasma progesterone (Days 6 and 9 groups; P < 0.05). Treatment with purified OIF did not induce ovulation in heifers, but hastened new follicular wave emergence in prepubertal heifers, influenced follicular dynamics in a phase-specific manner in mature heifers, and was luteotrophic.

Effect of a DNA vaccine harboring two copies of inhibin α (1-32) fragments on immune response, hormone concentrations and reproductive performance in rats

The objective was to investigate the effects of a novel DNA vaccine (pcISI) harboring two copies of inhibin α (1-32) fragments on immune response, hormone concentrations and reproductive performance in rats. Female Wistar rats (n = 18 per group) were immunized (twice, 4 wk apart) with 10, 50, or 100 μg (T1, T2 and T3, respectively), of the pcISI plasmid. At 4 wk after the second immunization, plasma antibody titers were higher (P < 0.05) in T3 than in either T1 or T2 (0.341 ± 0.123, 0.236 ± 0.068, and 0.251 ± 0.077, respectively, mean ± SD). Concurrrently, plasma concentrations of FSH and estradiol were highest (P < 0.05) in T3, and were higher (P < 0.05) in T1 and T2 than in control groups. For antibody-positive rats, there was a correlation (P < 0.01) between antibody titer and FSH concentrations after two pcISI immunizations. The number of mature follicles in the T3 group (46.00 ± 4.65) was higher (P < 0.05) than in two control groups (29.25 ± 3.72 and 27.92 ± 3.48), and also higher (P < 0.05) than in T1 and T2 (37.17 ± 4.99 and 38.75 ± 7.09). Antibody-positive rats had more mature ovarian follicles than negative rats (46.75 ± 4.23 vs. 35.60 ± 3.38, P < 0.05). Moreover, litter size and number of placentas were increased (P < 0.05) in the pcISI immunization groups, except for the T1 group, compared to the control groups. In conclusion, the pcISI DNA vaccine successfully induced a humoral immune response, improved reproductive hormone concentrations, stimulated follicular development, and increased number of placentas and litter size. Furthermore, 100 μg yielded the best immune response.

Follicular and endocrinological turnover associated with GnRH induced follicular wave synchronization in Indian crossbred cows

The goal of this study was to record the hormonal and follicular turnover in Jersey crossbred cows when subjected for follicular wave synchronization using GnRH. Six healthy, non-lactating and regularly cycling Jersey crossbred cows (5–6 y) were used for the study. In the control group, the follicular wave pattern was ultrasonographically investigated in 18 cycles (3 cycles/cow). In the treatment group, GnRH analogue (buserelin acetate 10 μg im) was administered on Day 6 of the cycle and follicular wave pattern was studied in 12 cycles (2 cycles/animal). Follicular population was categorized based on their diameter Class I, ≤5 mm; Class II, >5–<9 mm; Class III, ≥9 mm) and the number of follicles in each category was determined on Day 6, Day 8 and Day 10. Plasma FSH and progesterone concentrations were estimated in both control and treatment groups. Out of 18 estrous cycles studied, 14 cycles (77.8%), three cycles (16.7%) and one cycle (5.6%) exhibited three-, two- and four-follicular waves per cycle, respectively. It was evident that the DF of Wave I established its dominance and was in the growing phase by Day 6 of the estrous cycle in all the normally cycling crossbred cows. The DF ovulated in all the animals (100%) in the mean interval of 27.7 ± 0.2 h after GnRH administration. A synchronized homogenous group of follicles emerged two days after GnRH injection (Day of 8.0 ± 0.0) in all the animals (100%). The combination of LH surge induced ovulation of DF (abrupt termination of Wave I) and FSH surge stimulated homogenous recruitment of Class I follicles, led to a synchronized emergence of follicular wave. All the GnRH treated cows had three follicular waves because of early emergence and short period of dominance of Wave II DF.

Treatment with recombinant equine follicle stimulating hormone (reFSH) followed by recombinant equine luteinizing hormone (reLH) increases embryo recovery in superovulated mares

The dynamics of ovarian follicular development depend on a timely interaction of gonadotropins and gonadal feedback in the mare. The development and efficacy of genetically cloned recombinant equine gonadotropins (reFSH and reLH) increase follicular activity and induce ovulation, respectively, but an optimum embryo recovery regimen in superovulated mares has not been established. The objective of this study was to determine if treatment with reFSH followed by reLH would increase the embryo per ovulation ratio and the number of embryos recovered after superovulation in mares. Sixteen estrous cycling mares of light horse breeds (4–12 years) were randomly assigned to one of two groups: Group 1; reFSH (0.65 mg)/PBS ( n = 8) and Group 2; reFSH (0.65 mg)/reLH (1.5 mg) ( n = 8). On the day of a 22–25 mm follicle post-ovulation mares were injected IV twice daily with reFSH for 3 days (PGF 2α given IM on the second day of treatment) and once per day thereafter until a follicle or cohort of follicles reached 29 mm after which either PBS or reLH was added and both groups injected IV twice daily until the presence of a 32 mm follicles, when reFSH was discontinued. Thereafter, mares were injected three times daily IV with only PBS or reLH until a majority of follicles reached 35–38 mm when treatment was discontinued. Mares were given hCG IV (2500 IU) to induce ovulation and bred. Embryo recovery was performed on day 8 day post-treatment ovulation. Daily jugular blood samples were collected from the time of first ovulation until 8 days post-treatment ovulation. Blood samples were analyzed for LH, FSH, estradiol, progesterone and inhibin by validated RIA. Duration of treatment to a ≥35 mm follicle(s) and number of ovulatory size follicles were similar between reFSH/reLH and reFSH/PBS treated mares. The number of ovulations was greater ( P < 0.01) in the reFSH/reLH group, while the number of anovulatory follicles was less ( P < 0.05) compared to the reFSH/PBS group. Number of total embryos recovered were greater in reFSH/reLH mares than in the reFSH/PBS mares ( P ≤ 0.01). The embryo per ovulation ratio tended to be greater ( P = 0.07) in the reFSH/reLH mares. Circulating concentrations of estradiol, inhibin, LH and progesterone were not statistically different between groups. Plasma concentrations of FSH were less ( P < 0.01) in the reFSH/reLH treated mares on days 0, 1, 4, 6, 7 and 8 post-treatment ovulation. In summary, reFSH with the addition of reLH, which is critical for final follicular and oocyte maturation, was effective in increasing the number of ovulations and embryos recovered, as well as reduce the number of anovulatory follicles, making this a more viable option than treatment with reFSH alone. Further evaluation is needed to determine the dose and regimen of reFSH/reLH to significantly increase the embryo per ovulation ratio.

Effect of Short Period Vasectomy on FSH, LH, Inhibin and Testosterone Secretions, and Sperm Motility in Adult Male Rats

The present study was undertaken to clarify changes in secretions of FSH, LH, inhibin and testosterone, and sperm motility after bilateral vasectomy in adult male rats. Bilateral vasectomy was created surgically (treated group) and intact rats were used as control (control group). On days 3, 5, 7, 14, 30, 60, and 90 after surgery, plasma concentrations of FSH, LH, inhibin, and testosterone were measured by radioimmunoassay, and sperm motility characteristics were measured by computer-assisted sperm analysis (CASA). The results show that weights of epididymides significantly increased in vasectomized rats as compared to control rats. Histologically, damage to spermatogenesis was observed in vasectomized rats. Multinucleated giant cells were observed in the lumen of some seminiferous tubules, and there were degenerative spermatids in the epididymides of vasectomized rats. Plasma levels of LH, FSH, and testosterone only decreased on day 3 after vasectomy; however, plasma levels of ir-inhibin significantly increased on day 3 after vasectomy. In addition, the sperm motility parameters, straight-line velocity, curvilinear velocity, deviation of the sperm head from the mean trajectory and the maximum amplitude of lateral head displacement were decreased from day 60 after vasectomy. These results suggest that vasectomy reduces sperm motility starting from day 60 after vasectomy, and early bilateral vasectomy does not strongly affect the endocrine function of the testis, though it may result in damage to spermatogenesis in vasectomized rats.

Ultrasonographic and endocrine aspects of follicle deviation, and acquisition of ovulatory capacity in buffalo (Bubalus bubalis) heifers

The objectives of this study were to determine the interval from ovulation to deviation and the diameter of the dominant (DF) and largest subordinate (SF) follicles at deviation in buffalo (Bubalus bubalis) heifers. Two methods of evaluation (observed vs. calculated) were used. FSH and LH profiles encompassing follicle deviation (Experiment 1), and the follicular diameter when the DF acquired ovulatory capacity (Experiment 2) were also determined. The time of deviation and the diameter of the DF and the largest SF at deviation did not differ between observed and calculated methods. Overall, follicle deviation occurred 2.6±0.2d (mean±SEM) after ovulation, and the diameters of the DF and SF at deviation were 7.2±0.2 and 6.4±0.2mm, respectively. No changes in plasma levels of FSH or LH were observed (P=0.32 and P=0.96, respectively). Experiment 2 was conducted in two phases according to the diameter of the DF during the first wave of follicular development at the time of LH challenge (25mg of pLH). In the first phase, follicles ranging from 5.0 to 6.0mm (n=7), 6.1 to 7.0mm (n=11), or 7.1 to 8.0mm (n=9) were used, and in the second phase, follicles ranging from 7.0 to 8.4mm (n=10), 8.5 to 10.0mm (n=10), or 10.1 to 12.0mm (n=9) of diameter were used. After the pLH treatment, the DF was monitored by ultrasonography every 12h for 48h. No ovulations occurred in heifers in the first phase. However, in the second phase, an effect of follicular diameter was observed on ovulation rate [7.0–8.4mm (0.0%, 0/10), 8.5–10.0mm (50.0%, 5/10), and 10.0–12.0mm (55.6%, 5/9)]. In summary, follicle deviation occurred 2.6d after ovulation in buffalo (B. bubalis) heifers, when the diameters of the DF and SF were 7.2 and 6.4mm, respectively. No significant changes in plasma concentrations of FSH or LH were detected. Finally, the acquisition of ovulatory capacity occurred when the DF reached 8.5mm in diameter.

176 EFFECTS OF VEHICLE AND ROUTE OF ADMINISTRATION OF LETROZOLE ON OVARIAN FUNCTION IN CATTLE

Treatment with letrozole, a non-steroidal aromatase inhibitor, has been associated with elevated mean plasma LH concentrations, a prolonged period of dominance of the extant dominant follicle, and delayed emergence of the next follicular wave in cattle. As well, a luteotrophic effect was hypothesised by the observation that CL diameter was increased in heifers given 250 μg kg–1 of letrozole divided in a 3-day regimen. The objective of the present study was to determine the effects of vehicle and route of administration of letrozole on ovarian function in sexually mature beef heifers. Ovarian function was synchronized among heifers using transvaginal ultrasound-guided follicular ablation followed by a luteolytic dose of PGF b.i.d. 4 days later. The ovaries were subsequently examined daily by transrectal ultrasonography until ovulation was detected. On Day 3 (Day 0 = ovulation), heifers were assigned randomly to 4 treatment groups and given letrozole at a dose of 1 mg kg–1 intravenously (i.v. in benzyl alcohol, n = 10) or intramuscularly (i.m. in benzyl alcohol plus canola oil 1:1 v/v, n = 10), or given a placebo (i.v. in benzyl alcohol, n = 5) or (i.m. in benzyl alcohol plus canola oil 1:1 v/v, n = 5). The ovaries were monitored daily by ultrasonography, and blood samples collected twice daily by jugular venipuncture from pre-treatment to post-treatment ovulations. Comparisons among groups were made by 1-way ANOVA for single-point measurements and by ANOVA for repeated measures for time-series data. The interovulatory interval did not differ among groups, nor did the day-to-day diameter profile of the dominant follicle of wave 1 (first follicular wave after ovulation). However, the interval between emergence of waves 1 and 2 was longer in heifers treated with letrozole i.m. (11.7 ± 0.3 days) than in controls (10 ± 0.4 and 9.5 ± 0.5 days for i.v. and i.m. controls, respectively; P &lt; 0.05), and intermediate in heifers given letrozole i.v. (10.6 ± 0.30 days). The day-to-day diameter profile of the corpus luteum was greater (P &lt; 0.05), and plasma progesterone concentrations tended to be greater (P &lt; 0.06) in heifers treated i.m. with letrozole v. placebo. Plasma LH concentrations did not differ among groups, whereas plasma FSH concentrations were greater (P &lt; 0.02) in heifers treated i.v. with letrozole v. placebo. In summary, letrozole dissolved in benzyl alcohol and given intravenously at a dose of 1 mg kg–1 on Day 3 did not alter ovarian function in cattle, but the same dose given i.m. in canola oil vehicle resulted in a longer inter-wave interval, a greater CL diameter profile, and greater plasma progesterone concentrations. We conclude that i.m. letrozole in oil is a feasible route of administration and vehicle for the development of an aromatase inhibitor-based treatment for herd synchronization in cattle. Research supported by the Natural Sciences and Engineering Research Council of Canada, Canadian Institutes for Health Research, and Bioniche Life Science Inc.

Intraperitoneal kisspeptin-10 administration induces dose-dependent degenerative changes in maturing rat testes

AimsKisspeptin, a peptide secreted by hypothalamic neurons, is a critical regulator of reproduction and puberty but its role in the regulation of gonadal maturation in sexually immature males is elusive. The present study investigated the effects of 12days of pulsatile kisspeptin administration on gonadotropins and testosterone release and maturation of immature male gonads. Main methodsKisspeptin-10 was administered intraperitoneally at different dosage concentrations (1μg, 1ng, and 10pg) to 5weeks old prepubertal male rats, twice daily for 12days. Plasma LH, FSH and testosterone concentrations were measured through competitive-binding radioimmunoassay. Spermatogenesis was studied mainly at stage VII of the spermatogenic cycle through light and electron microscopy. Key findingsAt the end of the treatments plasma LH and testosterone concentrations were reduced significantly at 1ng and 1μg kisspeptin doses (P<0.05; P<0.01). Type A spermatogonia, preleptotene spermatocytes, pachytene spermatocytes, step 7 spermatids, elongated spermatids and daily sperm production decreased significantly (P<0.05). Sertoli cell efficiency and total support capacity of Sertoli cells were reduced at all doses (P<0.05). Meiotic index decreased (P<0.05) at 1μg dose only, whereas coefficient of mitosis increased at 1ng and 1μg (P<0.01) kisspeptin doses. Histologically, degeneration of seminiferous tubules was evident showing tubular necrosis, multinucleated giant cell formation, intratubular vacuolization, widened lumen and deshaped germ cells. Marked ultrastructural changes characterized by thin basal laminae, enlarged intratubular spaces, abnormal acrosome and disrupted germ cells were noticeable. SignificanceIn conclusion long-term kisspeptin-10 administration negatively regulates gonadal maturation in prepubertal testes.

Serum adiponectin and resistin in relation to insulin resistance and markers of hyperandrogenism in lean and obese women with polycystic ovary syndrome

Objectives It seems that adipokines participate in disturbances of the function of the hypothalamus–pituitary–ovary axis. The aim of the study was to assess the relationship between plasma adiponectin and resistin levels and insulin resistance and markers of hyperandrogenism in lean and obese PCOS women. Study design Forty-one women with PCOS (22 lean and 19 obese) and 16 healthy lean women were enrolled. Body mass and height were measured and body mass index was calculated. In addition to serum glucose, lipids, androgens and insulin, adiponectin and resistin concentration were assessed in the fasting state. The insulin resistance was calculated based on the HOMA-IR. Results Similar serum resistin concentrations were found in both PCOS subgroups and controls. The obese PCOS subgroup was characterized by the lowest serum adiponectin level (10.8 ± 8.3, compared with 21.0 ± 15.1 in the normal weight PCOS subgroup and 26.7 ± 12.5 μg/ml in controls). There were no correlations between resistin and adiponectin levels and HOMA-IR values and serum androgen concentrations. Significant positive correlations between adiponectin to resistin ratio and plasma FSH ( r = 0.49; p = 0.001) and LH ( r = 0.45; p = 0.003) concentrations, and a negative correlation with free androgen index ( r = −0.34; p = 0.03) in PCOS group were found. Conclusions Obese but not normal weight PCOS women have lower adiponectin levels whereas resistin concentration did not differ in normal weight and obese PCOS compared to control subjects. We hypothesize that changes of the relative proportion of adiponectin to resistin, but not circulating adiponectin and resistin levels themselves, may play a role in hormonal disturbances but not in insulin resistance in PCOS.

Profiles of Circulating Steroid Hormones, Gonadotropins, Immunoreactive Inhibin and Prolactin During Pregnancy in Goats and Immunolocalization of Inhibin Subunits, Steroidogenic Enzymes and Prolactin in the Corpus Luteum and Placenta

The current study was performed to follow up the circulating hormonal changes and to correlate the findings with the physiological activity of the corpus luteum (CL) and placenta during pregnancy in goats. Blood samples were collected weekly from five goats during pregnancy for measuring steroid and protein hormones. A gradual increase was observed in immunoreactive (ir-) inhibin, with maximal levels at the 17th week. The plasma concentrations of estradiol and prolactin (PRL) showed nearly similar patterns during pregnancy, where they declined to basal levels during the first 4 weeks post-breeding and then increased significantly, with the maximal concentration during late pregnancy. The plasma FSH and LH concentrations were maintained at basal levels throughout the gestation period. The plasma progesterone concentration abruptly increased in the first week post-breeding and remained at high values throughout the pregnancy period. Immunohistochemical localization of inhibin alpha, beta(A), beta(B) and steroidogenic enzymes cytochrome P450 aromatase, 3alpha-hydroxysteroid dehydrogenase (3betaHSD), cytochrome 17alpha-hydroxylase P450 and cholesterol side-chain cleavage cytochrome P450 in the cyclic and pregnant goat CL revealed positive immunoreactivity without affinity differences between the luteal and pregnancy stages. The placental syncytiotrophoblasts also showed positive staining, except for inhibin beta(A) and 3betaHSD. The giant binucleate cells of the placenta showed positive immunoreactions to PRL. These results suggest that the high concentrations of ir-inhibin, estradiol and PRL during late pregnancy are of placental origin and that the placenta may have a vital role in the maintenance of pregnancy, regulation of mammary growth and preparation for kidding and lactation in goats.

Endocrine Profiles of Oestrous Cycle in Buffalo: A Meta-analysis

A meta-analysis was conducted to summarize the results of studies which have described the profiles of hormones during the oestrous cycle in buffalo using a fixed effect model and a random effect model. Plasma progesterone concentrations were lowest (0.30±0.06 ng/ml) during the peri-oestrous phase and increased (p = 0.067) through the early luteal phase to a maximum concentration (1.94±0.03 ng/ml) during the mid-luteal phase. Circulating plasma inhibin and estradiol concentrations were lowest (0.31±0.01 and 11.04±0.13 ng/ml) during the mid-luteal phase, increased through the late luteal phase to maximum concentrations (0.44±0.02 and 22.48±0.32 ng/ml) during the peri-oestrous phase. Plasma FSH concentrations were lowest during the early luteal phase and increased through the mid-luteal phase to a maximum concentration during the peri-oestrous phase. Peripheral prolactin concentrations were lowest during the late luteal phase and increased to a maximum concentration during the peri-oestrous phase which then declined (p = 0.716) during the early luteal phase. Peripheral plasma cortisol concentrations decreased from 2.68±0.14 ng/ml during the early luteal phase to 1.43±0.27 ng/ml during the mid-luteal phase (p<0.001) which then increased to 2.06±0.17 ng/ml during the late luteal phase. Plasma T 3 concentrations decreased from the late luteal phase to the peri-oestrous phase (p<0.001) which then increased during the early luteal phase. T 4 concentrations increased from the late luteal phase to the peri-oestrous phase which then decreased during the early luteal phase.

Intravenous Orexin Reduces LH Secretion in Castrated Camelus Dromedaries Fed a Sub-maintenance Diet

It has been shown that orexin has an inhibitory effect on gonadotropin secretions in non-ruminant animals. The goal of this study was to determine whether orexin affects LH, and FSH secretions in the camel, as a pseudo-ruminant animal, under different dietary energy content. Sixteen castrated camels were randomly divided into 4 groups. Animals in groups 1 and 2 were fed 100% and animals in groups 3 and 4 were fed 50% energy content in their diet for 20 days. After 20 days, animals in groups 1 and 3 received infusions of 1 μg orexin and groups 2 and 4 received infusions of 2 μg orexin into their jugular vein. Blood samples were collected from the jugular vein every 20 minutes from 4 h before the first infusion of orexin until 4 h after the last orexin infusion. Lower dietary energy intake and infusions of 2 μg but not 1 μg orexin significantly (p<0.01) decreased the mean plasma concentrations and pulse amplitudes of LH of the animals. Infusion of 1 and 2 μg orexin did not change the secretions of LH of the animals fed NE. Different energy dietary intake and infusion of 1 and 2 μg orexin did not change the mean plasma concentrations of FSH of the animals in all groups. Infusions of 1 and 2 μg orexin significantly (p<0.01) decreased the glucose levels of animals fed LE but not in NE fed animals. Additionally, plasma glucose levels of the LE-fed animals in groups 3 and 4 were significantly (p<0.01) lower than those of the animals in groups 1 and 2 fed NE diet. The results of this experiment indicated that orexin may negatively affect LH and FSH in camels with negative energy balance, but not in those with positive energy balance.

227 EFFECTS OF A SINGLE DOSE OF A NONSTEROIDAL AROMATASE INHIBITOR ON OVARIAN FUNCTION IN CATTLE

Many countries have banned the use of estrogenic products in farm animals. Nonsteroidal aromatase inhibitors prevent the body from producing its own estrogen. The effects on the ovary are thought to be a result of suppression of estrogen-producing follicles and a rebound in endogenous levels of FSH through the removal of the negative feedback effect of estradiol. An experiment was designed to determine the effects of a nonsteroidal aromatase inhibitor, letrozole, on ovarian function in cattle. The specific objective was to test the hypothesis that letrozole will arrest growth of the dominant follicle, resulting in emergence of a new follicular wave at a predictable interval post-treatment. Beef heifers were assigned randomly to 4 groups and given phosphate-buffered saline [control; (n = 10)] or letrozole at a dose of 500 (n = 9), 250 (n = 10), or 125 (n = 10) μgkg-1 i.v. 4 days after follicular ablation (≈ 2.5 days after wave emergence, at the time dominant follicle selection is manifest). Blood samples were collected and ovarian structures were monitored daily by transrectal ultrasonography. Analysis of variance for repeated measures, one-way ANOVA, paired t-test, and 2-sample t-test were applied to the analysis of the data. The diameter profile of the dominant follicle was larger in heifers treated with letrozole than in control heifers (P &lt; 0.05). The intervals from treatment to new wave emergence and from treatment to onset of regression of the extant dominant follicle were longer (P &lt; 0.05) in heifers treated with letrozole than in controls, although variances in the intervals were not different. A small but significant reduction in circulating estradiol concentration was observed, and plasma LH concentrations were higher (P &lt; 0.05) in letrozole-treated heifers than in controls. Lower plasma concentrations of FSH in letrozole-treated heifers than in controls (P &lt; 0.03) was interpreted as an indirect effect resulting from prolonged follicular dominance. In summary, a single dose of letrozole did not induce regression of the extant dominant follicle, nor did it directly affect FSH release. Conversely, letrozole extended the lifespan of the dominant follicle, in association with increased endogenous levels of LH, thereby delaying the next FSH surge and subsequent follicular wave emergence. Results suggest that letrozole has potential as a nonsteroidal method of controlling ovarian function in cattle but further studies are needed to clarify dosage and timing of treatment. Research supported by the Natural Sciences and Engineering Research Council of Canada and Bioniche Life Science Inc.

Genetic association between AZF region polymorphism and Klinefelter syndrome

Because of conflicting results about the association between azoospermic patients with Klinefelter syndrome (KFS) and azoospermia factor (AZF) polymorphism, and because nothing is known about the association of KFS with partial AZFc deletions, an association study was performed in Tunisian KFS patients. A total of 29 azoospermic patients and 13 fertile men were enrolled in this study. The classical microdeletions were found in six out of nine KFS patients (67%). Gr/Gr deletions and b2/b3 deletions are partial AZFc deletions. One KFS patient without classical microdeletions had a gr/gr deletion. This deletion (gr/gr) was observed in four out of 18 azoospermic patients without chromosomal abnormalities. In addition, two b2/b3 and one AZFc deletion were identified in this group. All KFS patients had elevated plasma FSH and LH concentrations, but normal plasma testosterone concentration. The testis biopsy of three samples with Y microdeletions revealed Sertoli cell-only syndrome. No Y microdeletions or partial AZFc deletions were found in the fertile group. It is concluded that in the patient population KFS patients may harbour Y microdeletions, and screening for these should be part of the diagnostic work-up, particularly in those considering assisted reproductive techniques. However, partial AZFc deletions might not play a role in predisposing genetic background for the phenotype of azoospermic KFS subjects.

Effects of hysterectomy and uterine extracts on the gonadotrophic hormones and the weight of endocrine organs of female rats.

The previous observation that hysterectomy of rats results in increased pituitary nucleic acid turnover was followed up by studies on pituitary function in hysterectomized adult female rats with or without treatment with charcoal-treated crude uterine aqueous extracts. Hysterectomy had no effect on the pituitary or plasma LH and FSH concentrations. Administration of crude uterine extracts diminished the post-castrational rise of the pituitary FSH content without affecting the plasma FSH or LH concentrations. Hysterectomy decreased body weight but increased adrenal weight of ovariectomized animals. However, the body weight and pituitary weight of both the intact and ovariectomized animals increased significantly following 14 days of treatment with uterine extracts. The ovarian weight of the intact rats was reduced by this treatment. The pituitary nucleic acid content of castrated but oestradiol-substituted rats was reduced by hysterectomy. Plasma corticosterone concentrations were not affected by the above mentioned treatments. Uterine extracts inhibited the basal and GnRH induced LH release from isolated pituitary cells in culture. The effects of hysterectomy and/or administration of crude uterine aqueous extracts show that the uterus contains biologically active, non-steroidal substances which affect pituitary function of adult female rats.

Plasma and pituitary gonadotropins and prolactin after hysterectomy and treatment with uterine extracts in female rats. A kinetic study.

The kinetic of changes in plasma concentrations and pituitary contents of FSH, LH, prolactin after hysterectomy and treatment with steroid-free uterine extracts were studied in adult, non-pregnant female rats. The post-castration rise of plasma and pituitary FSH and plasma LH was inhibited but the plasma prolactin was elevated by hysterectomy. Steroid-free uterine extracts from previously castrated animals increased the plasma FSH, LH and prolactin concentrations in hysterectomized females 48 hours after administration. Uterine extracts from intact and oestradiol-substituted-castrated animals decreased the pituitary prolactin content 48 h after single i.p. injection. Pituitary FSH and LH contents were not affected by single dose of uterine extracts at any time which were examined. It is concluded that the uterus may play some role in the synthesis and release of pituitary gonadotropins and prolactin.

The Effect of Galanin on the Mean Plasma Concentrations of LH and FSH in Female Goats Fed Different Levels of Their Energy Requirements.

The existence of a close relationship between energy status and reproductive function is well documented, but its underlying mechanisms remain to be fully unfolded. Galanin is an orexigenic agent and has been demonstrated as putative regulator of gonadotropin secretion in rats, but whether galanin acts similarly in ruminants is unknown, therefore the goal of this study was to determine whether galanin affects the mean plasma concentrations of LH and FSH in the female saanen goats fed different energy content in diets. Nine female saanen goats were randomly divided into 3 groups. Animals of all groups were fed either 50%, 100%, or 150% energy content in diet for a month. After a month, goats received 1 μg galanin/kg body weight into their jugular vein. Blood samples were collected every 30 minutes from jugular vein of all goats 4 h before and 4 h after injection of galanin. Blood plasma was assayed for plasma LH and FSH concentrations by RIA. Injection of galanin only in 150% dietary energy intake significantly decreased the mean plasma concentrations of LH and FSH whereas in 50% and 100% dietary energy intake, injection of galanin had no effect on the mean plasma concentrations of LH and FSH. These results indicated that galanin may negatively affect mean plasma concentrations of LH and FSH in the female saanen goats only with positive energy balance. (poster)

The efficacy of recombinant equine follicle stimulating hormone (reFSH) to promote follicular growth in mares using a follicular suppression model

The efficacy of a recently engineered single chain recombinant equine follicle stimulating hormone (reFSH) was investigated in estrous cycling mares whose gonadotropins and follicular activity had been suppressed by concurrent treatment with progesterone and estradiol (P&E). Time of estrus was synchronized in 15 estrous cycling mares during the breeding season with prostaglandins F 2α (PGF 2α). The day after ovulation, mares were treated once daily with P&E for 14 days. Mares received a second injection of PGF 2α on day 6 of the synchronized estrous cycle to induce luteolysis. On day 8 post-ovulation mares were randomly assigned to three groups: small dose reFSH-treatment group (0.5 mg reFSH IV, twice daily); large dose reFSH-treatment group (0.85 mg reFSH IV twice daily); control group (saline IV, twice daily). reFSH treatment occurred concurrently with the last week of P&E treatment. After a follicle or cohort of follicles reached 35 mm in diameter, mares were injected with 0.75 mg of recombinant equine luteinizing hormone (reLH) to induce ovulation. Post-treatment ovulation was assessed. Daily blood samples were collected for analysis of FSH, LH, estradiol, progesterone, and inhibin by radioimmunoassay (RIA). On the first day of reFSH/saline treatment, blood samples were collected periodically from 1 h prior to treatment to 6 h post-injection via an indwelling jugular catheter to determine acute changes in FSH concentrations. Monitoring of follicular activity, estrus, and ovulation was performed daily by utilizing a stallion and transrectal ultrasonography. A difference ( p ≤ 0.05) between the largest diameter follicle in the reFSH-treatment groups compared to controls occurred on day 14 post-ovulation, the day treatments ended, and the difference continued until day 21 post-ovulation. reFSH-treatment groups had larger ( p ≤ 0.05) numbers of 20–29 mm follicles (days 13–18), 30–34 mm follicles (days 15–20) and ≥35 mm follicles (days 16–21) than controls. Mares treated with reFSH, at either dose, took less time (average: 2.95 ± 0.42 days) to develop 2–3 times more pre-ovulatory follicles than control mares (7.8 ± 0.51 days) ( p ≤ 0.05). The number of ovulations between treated mares and controls were similar due to a greater incidence of ovulation failure in reFSH-treated mares. During reFSH treatment, concentrations of plasma FSH, inhibin and estradiol were greater ( p ≤ 0.05) compared to control concentrations. Plasma LH concentrations in reFSH-treated mares were suppressed and did not exhibit the ovulatory surge of controls ( p ≤ 0.05). Plasma progesterone concentrations were not different across groups. These findings demonstrate the specific effects of reFSH to increase number of total follicles including pre-ovulatory follicles in mares with endogenous pituitary gonadotropins and follicular growth suppressed by a regimen of P&E.

Dietary manipulation of Bos indicus × heifers during gestation affects the reproductive development of their heifer calves

The effect of nutrition during the first and second trimesters of pregnancy in composite beef heifers on reproductive parameters of their female calves was determined in the present study. At artificial insemination, heifers were assigned to one of four treatment groups (i.e. HH, HL, LowH and LL) depending on the level of crude protein intake (H = high; L = low) for first and second trimesters of pregnancy. Gonadotrophin concentrations and ovarian parameters were measured in their female calves at 5 and 23 months of age. Crude protein intake was positively associated with dam plasma urea (P < 0.001). The density of healthy follicles in heifers at the time of death was negatively correlated with dam plasma urea at Day 179 (P = 0.009). Heifers from LowH dams had a smaller-sized prepubertal largest ovarian follicle (P = 0.03) and lower densities of primordial and primary follicles (P = 0.02) and healthy antral follicles (P = 0.009) when they were killed. There was a positive correlation between plasma FSH concentrations at 5 and 23 months of age (P = 0.02), as well as between the sizes of the largest ovarian follicles at 6 and 23 months of age (P = 0.01). In conclusion, the reproductive development of heifers may be affected by prenatal nutrition during early and mid-gestation.

Immunodetection of NGF, trkA, p75 and Inhibin .ALPHA.-Subunit in Interstitial Cells of Golden Hamsters Treated with hCG

The aim of this study was to investigate the effect of luteinizing hormone (LH) surge on expression of nerve growth factor (NGF), trkA, p75 and inhibin alpha-subunit in ovarian interstitial cells of golden hamsters after human chorionic gonadotropin (hCG) treatment. NGF, two NGF receptors (trkA, p75) and inhibin alpha-subunit were immunolocalized by immunohistochemistry, and gonadotropins, steroid hormones and immunoreactive (ir-) inhibin concentrations were measured by radioimmunoassay. Stronger positive staining of NGF, trkA and p75 were found in interstitial cells at 6, 12 and 18 h after hCG injection in the treated group compared with the control groups. Inhibin alpha-subunit staining was found in interstitial cells at 12 and 18 h after hCG injection in the treatment group, but not in the control group. Plasma concentrations of progesterone increased significantly from 6 to 18 h after hCG treatment, whereas plasma concentrations of estradiol-17beta significantly decreased compared with the control group. An increased plasma concentration of FSH and decreased concentrations of ir-inhibin from 6 to 18 h after hCG treatment verified the negative relationship. There were no significant changes in the concentrations of LH in the hCG-treated group. In contrast, the typical preovulatory LH surge was found at 1700 h on day 4 (proestrus) in the control group. These results suggested that LH surge can induce expression of NGF, trkA, p75 and inhibin alpha-subunit in ovarian interstitial cells and that NGF, trkA, p75 and inhibin alpha-subunit may have a paracrine or autocrine role in modulation of ovarian interstitial cell function in golden hamsters.