Effects of thyroid hormones on bovine granulosa and thecal cell function in vitro: dependence on insulin and gonadotropins

Associations between a normal-range free thyroxine concentration and ovarian reserve in infertile women undergoing treatment via assisted reproductive technology

BACKGROUND

Some recent studies have shown that female subclinical hypothyroidism (SCH) is associated with diminished ovarian reserve (DOR). In this study, we aimed to investigate whether serum-free thyroxine (fT4) concentrations within the reference range are associated with ovarian reserve in women.

METHODS

This cross-sectional study included 4933 infertile women with normal-range fT4 concentrations who received assisted reproductive technology treatment in our clinic. The data of women in different fT4 concentration tertiles (namely 12-15.33, 15.34-18.67, and 18.68-22 pmol/L) were compared with ovarian reserve markers, namely the anti-Müllerian hormone (AMH) concentration, the antral follicle count (AFC), and the number of aspirated oocytes. The primary outcomes were the AMH concentration and the risk of DOR, diagnosed as an AMH concentration < 1.1 ng/mL.

RESULTS

The average ages of women in the low-normal, middle-normal, and high-normal fT4 tertiles were 33.20 (standard deviation [SD]: 5.11), 32.33 (SD: 5.13), and 31.61 (SD: 5.10) years, respectively (p < 0.0001). AMH concentrations (adjusted mean: 3.32 [95% confidence interval {CI}: 3.16 to 3.50] vs. 3.51 [3.40 to 3.62] vs. 3.64 [3.50 to 3.80] ng/mL, p = 0.022) were significantly different between the fT4 concentration tertiles. The risk of DOR was significantly increased in the low-normal (adjusted odds ratio: 1.61 [95% CI: 1.01 to 2.58]) and middle-normal (1.47 [95% CI: 1.00 to 2.16]) tertiles compared with the high-normal tertile. Subgroup analysis showed that AMH concentrations were significantly different among the fT4 concentration tertiles in women aged < 35 years (adjusted mean: 3.94 [95% CI: 3.70 to 4.20] vs. 4.25 [4.11 to 4.39] vs. 4.38 [4.18 to 4.58], p = 0.028), whereas this difference was not significant in women aged ≥ 35 years (p = 0.534). The general additive models using fT4 as a continuous variable indicated that a lower fT4 concentration within the normal range was significantly associated with a lower AMH concentration (p = 0.027), a lower AFC (p = 0.018), a lower number of aspirated oocytes (p = 0.001), and a higher risk of DOR (p = 0.007).

CONCLUSION

Low-normal fT4 concentrations are associated with lower ovarian reserve in infertile women.

Treatment of Inactive Ovaries of Holstein Dairy Cows by Epidural Injection of GnRH Analogue (Receptal) and Its Impact on the Reproductive Hormones, Oxidant/Antioxidant Profile and Micro and Macro-Elements Profile

This study was designed to evaluate a new therapeutic approach for inactive ovaries based on the epidural administration of a GnRH agonist (Receptal) and an investigation of the impact of this treatment on the hormonal, oxidant/antioxidant and micro- and macro-element profiles. Sixty cows with postpartum anestrus were divided into two groups: the first group (group R_epid, n = 30) was administered an epidural injection of Receptal, while the second group (group C_epid, n = 30) received saline and was considered the control group. Evaluation of hormonal (progesterone, FSH, LH, testosterone, and cortisol), oxidant/antioxidant (MDA, SOD, GPx and TAC) as well as micro- and macroelement (calcium, phosphorus, manganese and magnesium) profiles was done in serum. The results showed that the epidural injection of Receptal has the potential to induce estrus response and conception incidence in treated cows. Compared to the control group, progesterone, FSH, and LH concentrations were significantly increased in the treated group, whereas testosterone and cortisol decreased (p < 0.05) following treatment. In addition, the treated group had greater TAC and GPx concentrations than the control group. Serum concentrations of magnesium increased (p < 0.05) following receptal treatment, but differences in other minerals were not detected. This research suggests a novel, effective method of treating inactive ovaries with epidural infusion of a GnRH agonist.

Dimethyl itaconic acid improves viability and steroidogenesis and suppresses cytokine production in LPS-treated bovine ovarian granulosa cells by regulating TLR4/nfkβ, NLRP3, JNK signaling pathways

The stimulation of pro-inflammatory pathways by lipopolysaccharide (LPS) endotoxins is a key player in the pathological mechanisms involved in the development of ovarian dysfunctions in dairy cows. Dimethyl itaconate acid (DMIA) is a novel immunometabolite that has recently emerged as a regulator of inflammatory responses in mammals. The present study was undertaken to determine the anti-inflammatory effects of DMIA on bovine granulosa cells (GCs) and to explore its possible molecular mechanisms. The ovarian GCs were obtained from small follicles of dairy cows. The GCs were stimulated with 1 μg/mL LPS for 4 h and then treated with 250 μM DMIA for 12 h. The viability, production of pro-inflammatory cytokines, activation of inflammatory signaling pathways and synthesis of steroid hormones were evaluated in treated GCs. Our results showed that DMIA reduced the inflammatory responses in LPS stimulated GCs by down-regulating the expression of nod-like receptor family pyrin domain containing 3 inflammasome, and toll-like receptor 4 and by suppressing the phosphorylation of nuclear factor kappa B and c-Jun N-terminal kinase proteins. DMIA also attenuated the increased production of pro inflammatory cytokines (interleukin 6, tumor necrosis factor α and interleukin 1 beta (p < 0.01) in LPS stimulated GCs. Exposure of LPS stimulated GCs to DMIA improved the impaired steroidogenesis by up-regulation of steroid synthesis genes including 3-beta-hydroxysteroid dehydrogenase, follicle stimulating hormone receptor and cytochrome P450 aromatase. The results of the present study highlight the potential role of itaconic acid for the improvement of GCs inflammation in dairy cows with ovarian dysfunctions.

Adaptive Responses of Thyroid Hormones, Insulin, and Glucose during Pregnancy and Lactation in Dairy Cows

The study examined the effects of different stages of pregnancy and lactation on thyroid, insulin, and glucose responses in dairy cows. In the present study, 30 dairy cows (10 Holstein, 10 Simmental, and 10 Brown) at 30 ± 20 d of lactation were randomly selected and blood samples were collected once every 60 d for one year to measure circulating thyroid stimulating hormone (TSH), total and free triiodothyronines (T3, fT3) and thyroxines (T4, fT4), insulin, and glucose. Pregnant cows showed higher T4 (p = 0.010) and insulin (p = 0.046) concentrations at >180 d than at >60−120 d of pregnancy and in nonpregnant cows. Along the lactation phase, circulating T4 concentrations showed a biphasic trend, decreasing from 0−60 d to >60−120 d phase, which showed the lowest values, and then increasing until the end of lactation (>300 d) (p = 0.016). Glucose showed the highest concentrations at the start of lactation (0−120 days) and the lowest values at the end (p = 0.008). The monitoring of thyroid hormones, insulin, and glucose changes represents an important tool to evaluate the anabolic and/or catabolic adaptation in response to functional periods in dairy cows, which can potentially predispose the cows to an excessive negative energy balance and related metabolic issues.

Plasma profile of follicle-stimulating hormone and sex steroid hormones after a single epidural administration of follicle-stimulating hormone via caudal vertebrae in Holstein dry cows

The conventional follicle-stimulating hormone (FSH) treatment for bovine superstimulation involves multiple intramuscular injections, which is stressful for animals and onerous. We herein investigated whether a single epidural injection of porcine FSH (pFSH) can induce superovulation and peripheral concentrations of pFSH and steroid hormones after the treatment in Holstein dry cows. We intramuscularly administered pFSH twice daily to three cows for 3 days (control) or a single epidural pFSH administration (epidural). Numbers of follicles (≥10 mm in diameter) at estrus and corpora lutea at luteal phase were counted by ultrasonography. Blood was sampled from 0 to 104 h after the first pFSH administration and plasma pFSH, progesterone, androstenedione, testosterone, and estradiol-17β concentrations were measured. Numbers of follicles (control: 18.3 ± 7.5, epidural: 15.7 ± 4.0; mean ± SD) and corpora lutea (control: 7.3 ± 4.2, epidural: 8.0 ± 2.6) were similar between both treatments. Plasma pFSH concentrations were higher in epidural than in control (p < 0.01). Although no significant differences were observed in progesterone, androstenedione, or estradiol-17β concentrations between the groups, testosterone concentrations were slightly lower with the epidural treatment than with the control treatment (p = 0.08). In conclusion, superovulation was induced by a single epidural injection of pFSH, which achieved higher pFSH level than the multiple injections in Holstein dry cows.

Induction of Twinning in Noemi Ewes Using Two Protocols of a Recombinant Human Follicle Stimulating Hormone Versus Porcine Pituitary-Derived FSH and their Subsequent Impacts on Maternal Hormones

Twinning induction of single-bearing Noemi ewes is an important avenue to maximize the economic feasibility of sheep production. Sixty Noemi ewes were used and randomly assigned to six treatment groups (n=10/group).Two sources of FSH [i.e., porcine (P) vs. human (H)] were given as a single dose or in six doses. The control 1 group was given a single dose of saline (C1), while the control 2 group was given six doses of saline (C6). Ewes in group 3 (P1) were given a single dose of p-FSH, in group 4 six doses of p-FSH (P6), in group 5 a single dose of h-FSH (H1), and in group 6 six doses of h-FSH (H6). The ewes were inserted with CIDR for 10 days with FSH given on day 8. A fertile ram was used at the onset of estrus. Blood samples were collected for hormone analyses. The time between CIDR removal and onset of estrus (63, 38 and 26 hrs. in C, P, and H, respectively) was shortened by FSH administration. FSH increased the incidence of twinning, however single dose resulted in more stillbirths and mortalities. The neonatal survival rate decreased in the P1 (40%) compared to the P6 (65%) treatments. Both sources of FSH raised progesterone and estradiol 17-β compared to the controls. Contrariwise, both h- and p-FSH reduced T4; however, h-but not p-FSH raised T3. In conclusion, using rh-FSH at six descending doses of a total 180 IU in Noemi ewes produced two viable neonates. Moreover, the exogenous FSH raised the sex hormones and T3 in the ewes.

Greater concentrations of IGF-1 are associated with increasing pregnancy rate in melatonin implanted anestrous Barki ewes

The present study was conducted to determine if increases in IGF-1 concentration, associated with treatment of ewes with melatonin, has beneficial effects on pregnancy rates when there is induction of estrus in anestrous ewes. A total of 120 multiparous lactating ewes were assigned to three groups (n = 10/group). Ewes of Group 1 were treated with a melatonin implant for 42 days followed by insertion of a controlled internal drug release (CIDR) device for 14 days with administration of equine chorionic gonadotropin (eCG) at day of CIDR removal. The ewes of Group 2 were treated with a CIDR and eCG at the same times as ewes of Group 1 and ewes of Group 3 were assigned to an be untreated control group. Melatonin implantation resulted in an increase in IGF-1 concentrations and lesser estradiol (E₂) and triiodothyronine (T₃) concentrations. Ewes of Groups 1 and 2 had the greatest progesterone (P₄) concentration compared ewes of Group 3. The E₂:P₄ ratio was less in ewes of Group 1 compared Group 3. Melatonin implantation of ewes resulted in a greater pregnancy rate compared to treatment with the CIDR and eCG which, in turn, had a greater rate than ewes of the control group. In conclusion, melatonin implantation modulates the hormonal milieu including P₄, E₂, T₃ and IGF-1 in seasonally anestrous ewes. Increased IGF-1concentrations, as a result of melatonin treatment, are associated with a greater percentage pregnancy rate when there is treatment of anestrous ewes to induce onset of estrus.

Effect of hypothyroidism on CYP51 and FSHR expression in rat ovary

Although thyroid hormone (TH) plays important roles in regulating ovarian development, the mechanism are still unclear. Cytochrome P450 lanosterol 14α-demethylase (CYP51) is a key enzyme in sterols and steroids biosynthesis that involved in folliculogenesis and oocyte maturation, which is regulated by follicle stimulating hormone (FSH). However, the effect of TH on CYP51 expression in ovarian cells is unclear. The objective of this study was to determine the effects of TH on CYP51 in rat ovary. Hypothyroidism rats were induced by 6-propyl-2-thiouracil (PTU), genes expressions in ovary were analyzed by Western blot or qRT-PCR. The data showed that CYP51 was significantly decreased in hypothyroidism, which was accompanied by the down-regulation of mRNA level. Meanwhile, similar tendency was also showed in FSHR expression in hypothyroidism. To evaluate the effect of the gonadotropin on CYP51 and FSHR expression in ovarian cells in vivo, hypo rats were injected subcutaneously with equine chorionic gonadotropin (eCG) respectively. The results showed that eCG reversed CYP51 and FSHR expression in hypo group. Moreover, FSH-induced CYP51 expression was meditated by FSHR. In addition, serum concentration of FSH and E₂ were also decreased in hypothyroidism, and E₂ was up-regulated by eCG treatment. These results indicate that hypothyroidism changes CYP51 and FSHR expression in ovary, which are regulated by gonadotropin. Moreover, genes changes in ovary are at least partially attributed to steroids biosynthesis.

Sexual function and depressive symptoms in young women with overt hyperthyroidism

OBJECTIVE

Despite high prevalence in a female population, surprisingly little is known about sexual functioning of women with thyroid hyperfunction. This study was aimed at assessing female sexual function and depressive symptoms in women with overt hyperthyroidism of autoimmune and non-autoimmune origin.

STUDY DESIGN

The study included three age-matched groups of young women inhabiting the Upper Silesia (a selenium-deficient and iodine-sufficient area): individuals with overt hyperthyroidism induced by Graves' disease (group A, n = 31), women with overt hyperthyroidism caused by toxic multinodular goiter or toxic adenoma (group B, n = 30) and women with normal thyroid function (group C, n = 34). Apart from measuring serum hormone levels, serum antibody titers and determining calculated parameters of thyroid homeostasis, all women completed questionnaires evaluating femalesexual function (FSFI) and depressive symptoms (BDI-II).

RESULTS

The mean total FSFI score and all domain scores were lower while the overall BDI-II score was higher in both groups of women with overt hyperthyroidism than in the control group, and correlated with thyrotropin and free thyroid hormone levels, as well as with the SPINA-GT index. The FSFI score as well as domain scores for desire, arousal and sexual satisfaction were lower, while the BDI-II score was higher in group A than in group B. In group A, the total FSFI score, desire, arousal, sexual satisfaction and severity of depressive symptoms correlated with TRAb and TPOAb titers.

CONCLUSION

The obtained results suggest that excessive thyroid hormone production and thyroid autoimmunity have an additive effect on sexual functioning and mood.

Sexual function and depressive symptoms in young women with hypothyroidism receiving levothyroxine/liothyronine combination therapy: a pilot study

Objective Even mild hypothyroidism in pre-menopausal women is accompanied by impaired sexual functioning. The study was aimed at comparing the effect of levothyroxine, administered alone or in combination with liothyronine, on sexual function and depressive symptoms in pre-menopausal women treated because of hypothyroidism. Methods This quasi-randomized, single-blind study included 39 young women receiving levothyroxine treatment who, despite thyrotropin and thyroid hormone levels within normal limits, still experienced clinical symptoms of hypothyroidism. These patients were divided into two groups: group A (n = 20) continued levothyroxine treatment, while group B (n = 19) received levothyroxine/liothyronine combination therapy. At the beginning of the study, and 6 months later, all participants of the study filled in questionnaires evaluating female sexual functioning (Female Sexual Function Index; FSFI) and the presence and severity of depressive symptoms (Beck Depression Inventory-Second Edition; BDI-II). Results The study was completed by 37 women. Baseline sexual functioning and depressive symptoms did not differ between the study groups. Neither the total FSFI score nor the domain scores changed throughout the study in women who continued levothyroxine treatment. Compared to levothyroxine administered alone, levothyroxine/liothyronine combination therapy increased scores for two domains: sexual desire and arousal, tended to increase the total FSFI score, as well as tended to decrease the overall BDI-II score. The effect of the combination therapy on sexual function correlated with a treatment-induced increase in serum levels of free triiodothyronine and testosterone. Conclusions The obtained results suggest that levothyroxine administered together with liothyronine is superior to levothyroxine administered alone in affecting female sexual functioning.

The influence of deoxynivalenol and zearalenone on steroid hormone production by porcine ovarian granulosa cells in vitro

Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEA) are frequently occurring in feed of pigs together. The aim of this study was to evaluate the possible in vitro effects of DON and ZEA, alone or their combination on steroid secretion of porcine ovarian granulosa cells (GCs). A species-specific model with porcine ovarian GCs was used to study the potential endocrine disrupting effects of DON and ZEA alone and in co-exposure. Progesterone (P4) and estradiol (E2) were determined by radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA). The results of this study demonstrate that DON alone at the higher concentrations may act to stimulate P4 (at 1,000, 2,000, 3,000 and 5,000 ng mL^-1 but not 10 and 100 ng mL^-1) and E2 (at 2,000, 3,000 and 5,000 ng mL^-1 but not 10, 100 and 1000 ng mL^-1) secretion. The effects of ZEA on P4 and E2 secretion were not confirmed. DON in combination with the other fusariotoxin ZEA may impair steroidogenesis. Results aslo demonstrate different toxicological effects of fusariotoxins on follicle stimulating hormone-induced secretion of P4 and E2. All these results taken together suggest that fusariotoxin and their interactions can impact ovarian steroidogenesis, thereby demonstrating their potential reproductive effects in pigs.

Subclinical hypothyroidism: Is it important in intracytoplasmic sperm injection cycles?

OBJECTIVE

To compare intracytoplasmic sperm injection (ICSI) outcomes of women with subclinical hypothyroidism with those of euthyroid women.

MATERIALS AND METHODS

A retrospective case-control study was conducted. Out of 2529 ICSI cycles evaluated, 41 women with hypothyroidism, 28 women with hyperthyroidism, and 128 women with subclinical hyperthyroidism were excluded, and 2336 cycles were analyzed. Women were identified as having subclinical hypothyroidism (case group, n=105) in the presence of a thyroid-stimulating hormone level >4.5 mU/L and normal free T4 and compared with euthyroid controls (n=2231).

RESULTS

The mean age, body mass index, day 3 follicle-stimulating hormone level, and antral follicle count of the study patients were similar to the control group (p>0.5). The cycle cancellation rate of the study group was similar to the control group (13.3% vs. 7.6%, p=0.1). The clinical pregnancy rate was 21.2% in the study group, which was significantly lower than the 35.8% in the control group (p=0.04). The take-home baby rate was also significantly lower in the study group compared with the control groups (13.5% vs. 31.4% respectively, p=0.01).

CONCLUSION

Both the clinical pregnancy rate and the take-home baby rate is lower in women with subclinical hypothyroidism at the time of ICSI cycle.

Co-administration of amygdalin and deoxynivalenol disrupted regulatory proteins linked to proliferation of porcine ovarian cells in vitro

Deoxynivalenol (DON) represents one of the most prevalent trichothecene mycotoxin produced by Fusarium species, causing economic and health impacts. On the other hand, amygdalin has been demonstrated to possess both prophylactic and curative properties, thus it has been used as a traditional drug because of its wide range of medicinal benefits, including curing or preventing cancer, relieving fever, suppressing cough, and quenching thirst. The aim of this in vitro study was to evaluate potential effects of natural product amygdalin combined with mycotoxin deoxynivalenol (DON) on the key regulators of cell proliferation and apoptosis in porcine ovarian granulosa cells. Ovarian granulosa cells were incubated for 24h with amygdalin (1, 10, 100, 1000, 10 000 μg.mL-1) combined with deoxynivalenol (1 μg.mL-1), while the control group remained untreated. The presence of proliferative (cyclin B1, PCNA) and apoptotic markers (caspase-3) in porcine ovarian granulosa cells after amygdalin treatment (1, 10, 100, 1000, 10 000 μg.mL-1) combined with deoxynivalneol (1 μg.mL-1) was detected by immunocytochemistry. The presence of proliferative (cyclin B1, PCNA) and apoptotic markers (caspase-3) in porcine ovarian granulosa cells was detected by immunocytochemistry. Co-administration of amygdalin plus DON significantly (p <0.05) increased the number of granulosa cells containing cyclin B1 and PCNA at all tested concetrations, when compared to control. However, percentage of granulosa cells containing major apoptotic marker caspase-3 did not differ after co-administration of amygdalin and DON. In summary, results form this in vitro study indicate that co-exposure of amygdalin and deoxynivalenol  may act to stimulate proliferation-associated peptides in porcine ovarian granulosa cells, and thus alter cell proliferation and normal follicular development.

Steroid and metabolic hormonal profile of porcine serum vis-à-vis ovarian follicular fluid

Aim:

This study was conducted to understand whether serum level of the steroid and metabolic hormones may be indicative of their level in ovarian follicular fluid (FF) in porcine, and its influence on fertility.

Materials and Methods:

Ovaries from pigs (n=32) of two genetic groups, namely, native (Ghungroo; n=16) and crossbred (Hampshire × Ghungroo; n=16) were collected. Both the genetic groups comprised gilts (n=8) and sows (n=8), and sows were in luteal phase of estrus cycle. FF was aspirated from small, medium and large follicles, and centrifuged for the collection of supernatant for further analysis. Blood samples were collected from the same animals, and serum was separated. Hormones, namely, cortisol, T3, T4 and testosterone were estimated by radioimmunoassay. Two-way ANOVA was used for analysis of data considering genetic background (native or crossbred), stage of reproductive life (gilt or sow), and source of sample (serum or FF) as fixed effects.

Results:

It was observed that all the hormones except cortisol differed significantly (p<0.01) based on genetic background. Stage of reproductive life and source of sample did not affect the studied hormonal level. Within the genetic groups, stage of reproductive life influenced T3 (p<0.01), cortisol (p<0.05) and testosterone (p<0.01) level in crossbred pigs as compared to T3 (p<0.01) only in native pigs. The level of T3 in serum, as well as FF, was higher (p<0.01) in Ghungroo gilts compared to sows. However, a reverse of this was observed in the case of crossbred pigs. The level of cortisol (p<0.05) and testosterone (p<0.01) was higher in crossbred sows than gilts in both serum and FF.

Conclusion:

The study revealed that serum level of the steroid and metabolic hormones is indicative of their level in the ovarian FF. Further, varying level of steroid and metabolic hormones in pigs based on genetic background may be due to variation in body size, rate of energy metabolism and stage of (re)productive life.

Changes in brain ribonuclease (BRB) messenger RNA in granulosa cells (GCs) of dominant vs subordinate ovarian follicles of cattle and the regulation of BRB gene expression in bovine GCs

Brain ribonuclease (BRB) is a member of the ribonuclease A superfamily that is constitutively expressed in a range of tissues and is the functional homolog of human ribonuclease 1. This study was designed to characterize BRB gene expression in granulosa cells (GCs) during development of bovine dominant ovarian follicles and to determine the hormonal regulation of BRB in GCs. Estrous cycles of Holstein cows (n = 18) were synchronized, and cows were ovariectomized on either day 3 to 4 or day 5 to 6 after ovulation during dominant follicle growth and selection. Ovaries were collected, follicular fluid (FFL) was aspirated, and GCs were collected for RNA isolation and quantitative polymerase chain reaction. Follicles were categorized as small (1-5 mm; pooled per ovary), medium (5-8 mm; individually collected), or large (8.1-17 mm; individually collected) based on surface diameter. Estradiol (E2) and progesterone (P4) levels were measured by radioimmunoassay (RIA) in FFL. Abundance of BRB messenger RNA (mRNA) in GCs was 8.6- to 11.8-fold greater (P < 0.05) in small (n = 31), medium (n = 66), and large (n = 33) subordinate E2-inactive (FFL E2 < P4) follicles than in large (n = 16) dominant E2-active (FFL E2 > P4) follicles. In the largest 4 follicles, GCs BRB mRNA abundance was negatively correlated (P < 0.01) with FFL E2 (r = -0.65) and E2:P4 ratio (r = -0.46). In experiment 2, GCs from large (8-22 mm diameter) and small (1-5 mm diameter) follicles were treated with insulin-like growth factor 1 (IGF1; 0 or 30 ng/mL) and/or tumor necrosis factor alpha (0 or 30 ng/mL); IGF1 increased (P < 0.05) BRB mRNA abundance, and tumor necrosis factor alpha decreased (P < 0.001) the IGF1-induced BRB mRNA abundance in large-follicle GCs. In experiment 3 to 6, E2, follicle-stimulating hormone, fibroblast growth factor 9, cortisol, wingless 3A, or sonic hedgehog did not affect (P > 0.10) abundance of BRB mRNA in GCs; thyroxine and luteinizing hormone increased (P < 0.05), whereas prostaglandin E2 (PGE2) decreased (P < 0.05) BRB mRNA abundance in small-follicle GCs. Treatment of small-follicle GCs with recombinant human RNase1 increased (P < 0.05) GCs numbers and E2 production. In conclusion, BRB is a hormonally and developmentally regulated gene in bovine GCs and may regulate E2 production during follicular growth in cattle.

Relationships between leptin, KiSS-1/GPR54 expression and TSH secretion from pituitary cells of pubertal ewes in vitro

Kisspeptin and leptin play a crucial role in the puberty of sheep as they initiate the activity of hypothalamic-pituitary-ovarian axis. Also hormones of thyrotropic axis are probably involved in this process. The aim of study was to analyze the impact of leptin on kisspeptin-10 secretion as well as kisspeptin-1 and G protein-coupled receptor (GPR54) mRNA expression in pituitary cells of pubertal ewes in vitro. The influence of kisspeptin on TSH secretion was also examined. Cells were cultured in McCoy's 5A medium without hormones; with 10(-10)-10(-5)M of leptin; with 10(-11)-10(-5)M of kisspeptin-10; with peptide 234 (10(-7)M, antagonist of GPR54) or 10(-11)-10(-5)M of kisspeptin-10 and peptide 234. Then, kisspeptin-10 and TSH secretion as well as KiSS-1 and GPR54 expression were analyzed. We found that leptin directly affected kisspeptin-10 secretion and kisspeptin-1/GPR54 expression in pituitary cells of pubertal ewes. Kisspeptin-10 did not change TSH secretion, except exerting a short-term influence after 2h.

Interaction between thyroglobulin and ADAMTS16 in premature ovarian failure

Objective

The aim of the present study was to examine whether interactions between polymorphisms in the thyroglobulin and ADAM metallopeptidase with thrombospondin type 1 motif, 16 (ADAMTS16) genes are associated with the development of premature ovarian failure (POF).

Methods

A total of 75 patients with POF and 196 controls were involved in this study. We used a GoldenGate assay to genotype single nucleotide polymorphisms (SNPs). Logistic regression analysis was performed to identify POF-associated polymorphisms and synergistic interactions between polymorphisms in the thyroglobulin and ADAMTS16 genes.

Results

Single gene analyses using logistic regression analysis showed no significant association between polymorphisms in the two genes and POF. In the results from interaction analyses, we found seven synergistic interactions between the polymorphisms in thyroglobulin and ADAMTS16, although there was no combination showing p-values lower than the significant threshold using the Bonferroni correction. When the AG genotype was present at the rs853326 missense SNP, the A and G alleles at the tagging SNPs rs16875268 and rs13168665 showed significant interactions (odds ratios=5.318 and 16.2 respectively; 95% confidence intervals, 1.64-17.28 and 2.08-126.4; p=0.0054 and 0.0079).

Conclusion

Synergistic interactions between polymorphisms in the thyroglobulin and ADAMTS16 genes were associated with an increased risk of POF development in Korean women.

The effect of nutrition and metabolic status on the development of follicles, oocytes and embryos in ruminants

The impact of nutrition and energy reserves on the fertility of ruminants has been extensively described. However, the metabolic factors and the molecular mechanisms involved in the interactions between nutrition and ovarian function are still poorly understood. These factors could be hormonal (either reproductive and/or metabolic) and/or dietary and metabolic (glucose, amino acids and fatty acids). In this review, we briefly summarize the impact of those nutrients (fatty acids, glucose and amino acids) and metabolic hormones (insulin/IGF-I, growth hormone, T3/4, ghrelin, apelin and the adipokines (leptin, adiponectin and resistin)) implicated in the development of ovarian follicles, oocytes and embryos in ruminants. We then discuss the current hypotheses on the mechanisms of action of these factors on ovarian function. We particularly describe the role of some energy sensors including adenosine monophosphate-activated kinase and peroxisome proliferator-activated receptors in the ovarian cells.

The role of thyroid hormones in regulation of chicken ovarian steroidogenesis

In all vertebrates, including birds, the normal development of the ovary and ovarian follicles is under the regulatory influence of hormones produced by the reproductive axis. In recent years, it has become clear that in birds an adequate level of thyroid hormones (THs), i.e. thyroxine (T4) and triiodothyronine (T3), in blood circulation is of primary importance for normal female reproductive functions. In avian species, characterized by seasonal reproduction, THs are involved in the photoperiodic regulation of reproduction acting at the mediobasal hypothalamus. In domestic fowl, where the seasonality of reproduction has been eliminated, the role of THs in ovarian function is not fully elucidated. Recent studies have revealed that ovarian follicles of the laying hen express mRNAs of TH nuclear receptors (TRα and TRβ0) as well as integrin (αVβ3) plasma membrane receptors, indicating genomic and nongenomic action of THs in the chicken ovary. In vivo experiments carried out on laying hens have showed that the bolus injection of T3 decreases levels of luteinizing hormone (LH) and estradiol (E2) in blood, and a hyperthyroid state evoked by administration of T3 for few days diminishes LH, E2 and progesterone (P4) levels, reduces the weight of the ovary, induces atresia of preovulatory follicles and eventually causes stoppage of egg laying. In vitro studies have demonstrated that T3 decreases E2 secretion from white nonhierarchical follicles and the theca layer of yellow preovulatory follicles, while on the other hand, it elevates P4 production from the granulosa layer of these follicles. These effects have been associated with steroidogenic enzyme expression and cyclic AMP synthesis. This review summarizes the current knowledge concerning the role of THs in regulation of steroidogenesis in chicken ovarian follicles.

Discovery of single nucleotide polymorphisms in candidate genes associated with fertility and production traits in Holstein cattle

Background

Identification of single nucleotide polymorphisms (SNPs) for specific genes involved in reproduction might improve reliability of genomic estimates for these low-heritability traits. Semen from 550 Holstein bulls of high (≥ 1.7; n = 288) or low (≤ −2; n = 262) daughter pregnancy rate (DPR) was genotyped for 434 candidate SNPs using the Sequenom MassARRAY® system. Three types of SNPs were evaluated: SNPs previously reported to be associated with reproductive traits or physically close to genetic markers for reproduction, SNPs in genes that are well known to be involved in reproductive processes, and SNPs in genes that are differentially expressed between physiological conditions in a variety of tissues associated in reproductive function. Eleven reproduction and production traits were analyzed.

Results

A total of 40 SNPs were associated (P < 0.05) with DPR. Among these were genes involved in the endocrine system, cell signaling, immune function and inhibition of apoptosis. A total of 10 genes were regulated by estradiol. In addition, 22 SNPs were associated with heifer conception rate, 33 with cow conception rate, 36 with productive life, 34 with net merit, 23 with milk yield, 19 with fat yield, 13 with fat percent, 19 with protein yield, 22 with protein percent, and 13 with somatic cell score. The allele substitution effect for SNPs associated with heifer conception rate, cow conception rate, productive life and net merit were in the same direction as for DPR. Allele substitution effects for several SNPs associated with production traits were in the opposite direction as DPR. Nonetheless, there were 29 SNPs associated with DPR that were not negatively associated with production traits.

Conclusion

SNPs in a total of 40 genes associated with DPR were identified as well as SNPs for other traits. It might be feasible to include these SNPs into genomic tests of reproduction and other traits. The genes associated with DPR are likely to be important for understanding the physiology of reproduction. Given the large number of SNPs associated with DPR that were not negatively associated with production traits, it should be possible to select for DPR without compromising production.

Cystic ovarian follicles and thyroid activity in the dairy cow

Thyroid activity affects the functionality of the reproductive axis and thyroid dysfunction has been associated with ovarian hyperstimulation syndrome and polycystic ovarian syndrome, in human medicine. This study investigates serum17-<beta> estradiol, progesterone, thyrotropic and thyroid hormone levels, in cyclic dairy cows on heat (Group H) and in dairy cows with ovarian follicular cysts (Group FC). Both 17-<beta> estradiol and progesterone serum concentrations were statistically higher in cystic than in cyclic cows (estradiol: 8.51±1.91 vs 6.32±1pg/mL) (progesterone: 0.49±0.17 vs 0.13±0.03ng/mL), whereas TSH and fT4 serum concentrations were statistically lower in cows with cystic ovarian follicles (COF), compared to cyclic ones (TSH: 2.48±1.31 vs 3.56±1.03ng/mL) (fT4: 5.86±1.69 vs 8.63±1.08). fT3 serum levels were similar, in both cystic and cyclic subjects (2.94±0.65 vs 3.02±0.9, respectively). Based on these results it was decided to examine the function of the thyrothropic axis of dairy cows in a similar manner to that conducted on humans. If severe hypothyroidism should be found, a hormone replacement therapy could be attempted in cystic cows refractory to "ordinary" therapies.

Effects of fibroblast growth factor 9 (FGF9) on steroidogenesis and gene expression and control of FGF9 mRNA in bovine granulosa cells

Gene expression of fibroblast growth factor-9 (FGF9) is decreased in granulosa cells (GC) of cystic follicles compared with normal dominant follicles in cattle. The objectives of this study were to investigate the effects of FGF9 on GC steroidogenesis, gene expression, and cell proliferation and to determine the hormonal control of GC FGF9 production. GC were collected from small (1-5 mm) and large (8-22 mm) bovine follicles and treated in vitro with various hormones in serum-free medium for 24 or 48 h. In small- and large-follicle GC, FGF9 inhibited (P < 0.05) IGF-I-, dibutyryl cAMP-, and forskolin-induced progesterone and estradiol production. In contrast, FGF9 increased (P < 0.05) GC numbers induced by IGF-I and 10% fetal calf serum. FGF9 inhibited (P < 0.05) FSHR and CYP11A1 mRNA abundance in small- and large-follicle GC but had no effect (P > 0.10) on CYP19A1 or StAR mRNA. In the presence of a 3β-hydroxysteroid dehydrogenase inhibitor, trilostane, FGF9 also decreased (P < 0.05) pregnenolone production. IGF-I inhibited (P < 0.05) whereas estradiol and FSH had no effect (P > 0.10) on FGF9 mRNA abundance. TNFα and wingless-type mouse mammary tumor virus integration site family member-3A decreased (P < 0.05) whereas T(4) and sonic hedgehog increased (P < 0.05) FGF9 mRNA abundance in control and IGF-I-treated GC. Thus, GC FGF9 gene expression is hormonally regulated, and FGF9 may act as an autocrine regulator of ovarian function by slowing follicular differentiation via inhibiting IGF-I action, gonadotropin receptors, the cAMP signaling cascade, and steroid synthesis while stimulating GC proliferation in cattle.

Epistasis between the HSD17B4 and TG polymorphisms is associated with premature ovarian failure

OBJECTIVE

To identify whether epistasis between TG and HSD17B4 and whether polymorphisms in HSD17B4 are associated with premature ovarian failure (POF).

DESIGN

Case-control genetic association study.

SETTING

Research laboratory of a university.

PATIENT(S)

Female patients with POF (98) and controls (218) of Korean ethnicity participated in this study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genotype distribution, haplotype (HT) inference, and gene-gene interaction.

RESULT(S)

Distribution of one haplotype (A-G-A-A-G-G) on the HSD17B4 gene was significantly different between the POF group and the control group in a dominant model. In addition, the combined effect of the single nucleotide polymorphisms (SNPs) HSD17B4 rs28943592 and TG rs2076740 was significantly associated with POF (odds ratio = 7.74, 95% confidence interval = 1.67-35.94), although a significant association was not observed in the single SNP model.

CONCLUSION(S)

A haplotype in the HSD17B4 gene was identified that was significantly associated with resistance to POF. In addition, epistasis between two missense SNPs (rs28943592, rs2076740) located in HSD17B4 and TG was significantly associated with susceptibility to POF.

Effect of 3,3',5-triiodothyronine and 3,5-diiodothyronine on progesterone production, cAMP synthesis, and mRNA expression of STAR, CYP11A1, and HSD3B genes in granulosa layer of chicken preovulatory follicles

In vitro studies were performed to assess whether stimulatory effects of triiodothyronine (T3) on progesterone (P4) production in a granulosa layer (GL) of chicken preovulatory follicles are associated with 3',5'-cyclic adenosine monophosphate (cAMP) synthesis and mRNA expression of STAR protein, CYP11A1, and HSD3B. Effects of 3,5-diiodothyronine (3,5-T2) on steroidogenic function in these follicles were also investigated. The GL of F3 to F1 follicles was incubated in medium supplemented with T3 or 3,5-T2, LH, or forskolin (F), and a combination of each iodothyronine with LH or F. Levels of P4 and cAMP in culture media were determined by RIA. Expression of genes involved in P4 synthesis (ie, STAR protein, CYP11A1, and HSD3B) in the GL of F3 to F1 follicles incubated in medium with T3 or 3,5-T2 and their combination with LH was performed by real-time PCR. Triiodothyronine increased basal and LH- and F-stimulated P4 secretion by preovulatory follicles. The 3,5-T2 elevated P4 synthesis by F3, had no effect on F2 follicles, and diminished P4 production by the GL of F1 follicles. It had no effect on LH-stimulated P4 production; however, it augmented F-stimulated P4 production by F2 and F1 follicles. Although T3 did not affect basal and F-stimulated cAMP synthesis by the GL of preovulatory follicles, it increased LH-stimulated synthesis of this nucleotide. However, 3,5-T2 elevated F-stimulated cAMP synthesis in F3 and F2 follicles; it did not change basal and LH-stimulated cAMP production. Triiodothyronine decreased basal STAR and CYP11A1 mRNAs in F3 follicles, increased them in F1 follicles, and elevated HSD3B mRNA levels in F1 follicles. Triiodothyronine augmented LH-stimulated STAR, CYP11A1, and HSD3B mRNA levels in F2 and CYP11A1 in F1 follicles. However, T3 decreased LH-stimulated STAR and HSD3B mRNA levels in F1 follicles. The 3,5-T2 did not affect basal STAR and CYP11A1 mRNA expression in all investigated follicles; however, it decreased LH-stimulated STAR expression in F2 and F1 ones. The effects of 3,5-T2 caused elevated basal but diminished LH-stimulated HSD3B mRNA levels. In conclusion, data indicate that both iodothyronines are involved in P4 production in the GL of chicken preovulatory follicles acting alone and additively with LH. Effects of iodothyronines depend on follicle maturation and are associated with modulation of cAMP synthesis and STAR, CYP11A1, and HSD3B mRNA expression. We suggest that iodothyronines participate in maturation and ovulation of chicken follicles.

Thyroglobulin gene is associated with premature ovarian failure

Variants of the thyroglobulin gene were significantly associated with premature ovarian failure in a Korean population. Three single nucleotide polymorphisms and one haplotype were found to be associated with a significant increase in the risk for premature ovarian failure.

Proliferative thyroid lesions and hyperthyroidism in captive fishers (Martes pennanti)

Diseases of the thyroid gland are common in many zoo species, but there are few descriptions of thyroid dysfunction in Mustelidae. A 7-yr-old, captive-bred female fisher (Martes pennanti) with progressive alopecia was diagnosed with clinical hyperthyroidism based on persistent elevation of both total and free serum thyroxine and triiodothyronine, ultrasound examination, and histologic evidence of adenomatous hyperplasia. Four additional geriatric adult fishers (two male and two female) were identified with thyroid adenomatous hyperplasia in a review of 23 postmortem records. Banked sera were available for thyroid hormone testing from three of the four necropsy cases. Total and free thyroxine were elevated in four of four animals tested, and triiodothyronine was elevated in two of three animals tested. Necropsy findings in four cases identified cardiac hypertrophy, congestive heart failure, and vascular lesions consistent with hypertension; complete tissues were not available from the remaining case. Clinical and subclinical hyperthyroidism may be a common but overlooked condition of captive fishers.

Thyroid hormone concentrations in systemic circulation and ovarian follicular fluid of cows

The aim of this study was to determine and compare the concentrations of total (T) and free (F) fractions of thyroid hormones (T3-triiodithyronine and T4-thyroxin) in peripheral circulation and follicular fluid of cows in relation to ovarian follicular status in vivo (Experiment 1), and in the follicles from the slaughterhouse ovaries (Experiment 2). In Experiment 1, estrus was synchronized in 15 cows using two Estrumate® (cloprostenol sodium) injections (250 mg cloprostenol intramuscular), the time of ovulation (Day 0) was confirmed by ultrasonography, and ovarian antral follicles were ablated on Day 5. The ensuing superovulatory treatment consisted of eight Folltropin®-V injections (50 mg intramuscular) administered twice daily from Day 6 to Day 9, followed by two injections of Estrumate® (Day 10 am and pm) and a single dose of Lutropin Alfa® (Day 11; 750 IU intramuscular). On Day 5, both TT3 and FT3 concentrations were greater ( P < 0.05) in serum than follicular fluid from dominant (DFs) or subordinate antral follicles (SFs), and TT4 concentrations were greater ( P < 0.05) in DFs compared with SFs. Serum concentrations of FT4 were greater ( P < 0.05) on Day 12 than on Day 5, and TT4 concentrations in follicular fluid collected on Day 12 were higher than those in DFs and SFs on Day 5. In Experiment 2, there were no differences ( P > 0.05) in thyroid hormone concentrations between the largest and all remaining antral follicles visible on the surface of the ovary ( n = 20 ovaries). We concluded that: (i) physiological status of bovine antral follicles (i.e. dominant versus subordinate) may impinge on the accumulation of TT4 in follicular fluid; and (ii) hormonal ovarian superstimulation increases circulating levels of FT4 and follicular fluid content of TT4.

Influence of triiodothyronine (T(3)) on secretion of steroids and thyroid hormone receptor expression in chicken ovarian follicles

The present study was designed to (1) assess the role of triiodothyronine (T(3)) with regard to in vitro steroid hormone secretion by chicken ovarian follicles; (2) determine whether T(3) influences the in vivo function of the pituitary-ovarian axis in the hen; and (3) detect expression of thyroid hormone receptor (TR) mRNA in chicken ovarian follicles. In the first experiment, laying hens were decapitated 22.5h before ovulation. White prehierarchical follicles (1-8mm) and fragments of theca and granulosa layers of the 3 largest yellow preovulatory follicles F3-F1 (22-35mm) were incubated in a medium supplemented with T(3) (0, 0.1, 1, 10, 100, or 1000ng/mL) or ovine luteinizing hormone (LH) (10ng/mL) in combination with doses of T(3) (1, 10, and 100ng/mL). Triiodothyronine decreased basal and LH-stimulated estradiol secretion by white follicles and the theca layer of all preovulatory follicles. On the other hand, it increased progesterone secretion by F2 and F1 follicles. In the second experiment, hens were injected 1h after ovulation with saline (control) or T(3) (10microg/100g body weight, intraperitoneally). Results indicated that exogenous T(3) decreased plasma concentrations of LH and estradiol and increased plasma concentrations of progesterone. In the third experiment, using reverse transcription polymerase chain reaction (RT-PCR) analysis, expression of thyroid hormone receptor (TRalpha and TRbeta0), mRNA was detected in all of the ovarian compartments. The expression of TRalpha mRNA was relatively greater in comparison with TRbeta0. There were no differences between white ovarian follicles in the expression of TRalpha and TRbeta0 mRNA. A considerably higher TRalpha and lower TRbeta0 expression was detected in the granulosa layer of preovulatory follicles in comparison with the theca layer. In conclusion, the data indicate that thyroid hormones acting via nuclear receptors are involved in regulation of the pituitary-ovarian axis and processes associated with follicle growth and maturation.

Effect of prepartum energetic supplementation on productive and reproductive characteristics, and metabolic and hormonal profiles in dairy cows under grazing conditions

The effect of cracked corn grain supplementation (3.5 kg/day) during 3 weeks before the expected calving date on milk production and composition, body condition score (BCS), metabolic and hormonal profiles and length of postpartum anoestrus was evaluated in multiparous Holstein dairy cows under grazing conditions (Energy supplemented group, n = 10; Control group, n = 10). Body condition score was weekly recorded during the peripartum period, from days -21 to +35 (parturition = day 0). Non-esterified fatty acids, beta-hydroxybutyrate, cholesterol, urea, insulin, insulin-like growth factor I (IGF-I), leptin, thyroxine (T(4)) and 3,3''5-triiodothyroinine (T(3)) were weekly determined in plasma from days -21 to +35. The reinitiation of ovarian cyclicity was twice weekly determined by ovarian ultrasonography and confirmed by plasma progesterone concentrations. Cows fed energy concentrate prepartum had higher BCS during the prepartum and postpartum and produced more milk. Non-esterified fatty acids plasma concentrations were significantly higher in the energy group, while cholesterol was higher in the control group. Treated cows had higher levels of plasma insulin, IGF-I and leptin pre-calving. IGF-I, leptin and T(4) were diminished during the early postpartum period in both groups. Insulin levels were also diminished in the control group, but levels remained high in the energy-supplemented group. Treated cows ovulated sooner after parturition than controls. We conclude that Energetic supplementation prepartum in cows under grazing conditions increased milk production and reduced the reinitiation of ovarian activity, consistent with a better EB (BCS), higher prepartum levels of IGF-I, leptin and insulin, and higher insulin levels during early postpartum.

Effect of plasma from cyclic versus nutritionally induced anovulatory beef heifers on proliferation of granulosa cells in vitro

The effect of plasma from cyclic versus nutritionally induced anovulatory beef heifers was evaluated on proliferation of bovine granulosa cells in vitro. Granulosa cells were obtained from small (1-5mm) follicles of cattle and cultured for 4 days. During the last 2 days of culture, cells were exposed to medium containing 0, 1 or 10% plasma from cyclic or anovulatory heifers in the presence or absence of IGF-I (100ng/ml). Cell numbers were determined. Regardless of source, increasing percentage of plasma to culture medium increased cell numbers. However, the plasma-induced increase was greater in granulosa cells exposed to cyclic heifer plasma versus anovulatory heifer plasma. In addition, concomitant treatment with IGF-I dramatically improved cell proliferation induced by anovulatory heifer plasma. These results indicate that plasma from cyclic heifers contain factors that are a greater stimulus to granulosa cell proliferation than plasma from anovulatory heifers. Systemic factors such as IGF-I may play a role in directly regulating granulosa cell proliferation in cattle.

Effects of estradiol on bovine thecal cell function in vitro: dependence on insulin and gonadotropins

The objective of this study was to evaluate the influence of estradiol (E2) on proliferation and steroid production by thecal cells obtained from large (> or =8 mm) follicles of cattle. Five experiments evaluated the effect of various doses of E2 during a 2-d exposure in serum-free medium on hormone-induced steroidogenesis and cell proliferation. In LH-treated thecal cells of experiment 1, 300 ng/mL of E2 decreased progesterone production by 30% and increased androstenedione production to 5.8-fold of controls. In the absence of LH, both 3 and 300 ng/mL of E2 increased progesterone production. In experiment 2, in the presence of insulin and LH, 3, 30, and 300 ng/mL of E2 decreased progesterone production (by 17 to 36%), whereas 3 ng/mL of E2 decreased and 300 ng/mL of E2 increased androstenedione production. Doses of LH (3 to 30 ng/mL) tested in experiment 3 increased (to as much as 3.7-fold) progesterone production by thecal cells and E2 attenuated this stimulatory effect by 40%. In contrast, E2 amplified the stimulatory effect of LH on androstenedione production in experiment 3. In experiment 4, E2 (300 ng/mL) decreased IGF-I- and insulin-induced thecal cell progesterone production by 70 to 77%, whereas E2 increased basal, IGF-I, and insulin-induced androstenedione production. In experiment 5, in the presence of insulin, 10 to 1000 ng/mL of E2 had no effect on [(125)I]-IGF-I binding to thecal cells, whereas 10 and 100 ng/mL of E2 increased and 1000 ng/mL of E2 decreased progesterone production by thecal cells. Estradiol had no consistent effect on thecal cell numbers among the 5 experiments. These results support the hypothesis that E2 may act as a paracrine factor to directly regulate hormone-induced steroid production by thecal cells without affecting cell numbers or numbers of insulin-like growth factor type I receptors.

Plasma concentrations of thyroxine in dairy cows exposed to 60 Hz electric and magnetic fields

Two experiments were carried out to assess the effects of electric and magnetic fields (EMF) on blood thyroxine (T4) in dairy cattle. In experiment 1, 16 lactating pregnant Holstein cows were exposed to 10 kV/m, 30 microTesla (microT) EMF. The animals were divided into two groups of eight animals each. Each group was exposed to EMF according to one of two treatment sequences of three periods of 28 days each. Sequence 1 was EMF OFF-ON-OFF and sequence 2 was EMF ON-OFF-ON. During the last day of each treatment period, blood samples were collected every 4 h for 24 h to estimate T4 plasma concentrations. In experiment 2, 16 nonlactating, nonpregnant, multiparous Holsteins were exposed to 10 kV/m, 30 microT EMF. The animals were divided into two groups of eight animals each. Each group was exposed to EMF according to one of the two treatment sequences described above, except that each period amounted to the number of days corresponding to one estrous cycle. During treatment, blood samples were collected every other day for T4 analysis. In both experiments, the light cycle emulated a short photoperiod (8 h light/16 h dark). During the ON periods, the animals were exposed to EMF for 16 h, 8 h of the light period plus the first 8 h of during the dark period. In experiment 1, exposed animals did not have any change in T4 plasma concentrations due to treatment (P = .0968), but, the time of sample collection revealed a significant difference (P = .0012). In experiment 2, the effect of period (P = .0009) and the treatment by days interaction (P = .0003) were statistically significant. We conclude that a worst case scenario exposure of dairy cattle to 10 kV/m, 30 microT EMF influences, in a moderate fashion, the blood levels of thyroxine.

In utero and lactational exposure of Long-Evans rats to ammonium perchlorate (AP) disrupts ovarian follicle maturation

Ammonium perchlorate (AP) is a powerful oxidizer manufactured almost exclusively for the aerospace industry. AP salts are also used in airbags, flares, fertilizers, enamels and paints. As a result of widespread industrial use, AP has become a persistent environmental contaminant of drinking water in several U.S. states. AP ion disrupts the trapping of iodide as well as facilitates the discharge of unorganified iodide from the thyroid gland. Such disturbances in thyroid hormone concentrations during critical periods of development are then known to cause profound reproductive and developmental defects, since thyroid hormones modulate both follicular development and steroidogenesis and affect estrogen metabolism and receptor. This study was designed (1) to determine whether exposure to a low or high concentration of AP (LAP, HAP) exerts detrimental effects on follicle maturation in the Long-Evans hooded rat and (2) to determine whether the modulatory effects of AP can be ameliorated by levo-thyroxine sodium (T4) supplementation. Animals were treated via deionized drinking water on GD 7-21 with LAP (0.4 mg/kg/day) or HAP (4.0 mg/kg/day). Half of each group was also given T4 supplements via drinking water on GD 7-21. Female pups were sacrificed on postnatal days 24/25, and the ovaries were excised, fixed for histology and analyzed. The analysis included a count, measurement and classification of preantral and antral follicles in the greatest cross-sectional area of the ovary. The results indicated that treatment with the HAP significantly reduced the number of preantral follicles <50,000 microm2 and the total number of antral follicles in the <50,000, 50-100,000 and >100,000 microm2 size classes. In ovaries treated with the LAP, we observed no significant decrease in preantral follicles of any size class and only a significant reduction in the largest antral follicles. T4 only circumvented the effect on the number of small preantral and antral follicles; however, a significant diminution in the antral follicle number persisted in the mid-sized (HAP) and large (LAP, HAP)-sized classes. These data support the hypothesis that AP reduces the number of preantral and antral follicles in certain size classes in rats exposed during a critical period of development, and that T4 can attenuate the effects of AP on small preantral and antral follicles, but not on medium or large antral follicles. (T35ES007292 & ES08342.).

Endocrine regulation of ovarian antral follicle development in cattle

Antral follicle growth in cattle occurs in two distinct phases; the first 'slow' growth phase spans the time from antrum acquisition to a size of approximately 3 mm detectable by transrectal ultrasound, and the second 'fast' phase is gondadotrophin-dependent and includes cohort growth, dominant follicle (DF) selection, and DF growth. This review summarises current concepts of the relative roles FSH and LH, ovarian and metabolic hormones play mainly in the second phase of antral follicle growth in animals of different reproductive and nutritional states. It is proposed that differential FSH response may enable one cohort follicle to become selected, and that follicular secretions, particularly inhibin, suppress FSH and thus are responsible for DF selection and dominance. Acute dependence of the DF on LH pulses will determine DF lifespan, and the LH pulse profile can be influenced by metabolic hormones such as leptin, providing one possible link for nutritional state and reproduction. Direct ovarian effects of acute and chronic changes in growth hormone, insulin and insulin-like growth factor (IGF)-I have been described on cohort follicles, DF oestrogen activity and on DF growth. Influences of metabolic hormones on early antral follicles undergoing their first 'slow' growth phase are less well described, yet metabolic hormones appear to enhance growth into the cohort available for FSH-induced emergence, and may influence subsequent developmental competence of oocytes.

Acute fasting in heifers as a model for assessing the relationship between plasma and follicular fluid NEFA concentrations

It is known from epidemiological studies that negative energy balance in early lactating dairy cows is related to a depression in reproductive performance. Elevated plasma concentrations of non-esterified fatty acids (NEFA) are a typical metabolic characteristic of these animals and are proposed as the possible link. The suggestion is that NEFA might have a direct effect on the ovary, by affecting development of the oocyte or the granulosa cells. However, no data is available concerning the relationship between the concentration of NEFA in follicular fluid and plasma. Therefore, a cross-over study with 10 heifers around 15 months of age was conducted to analyze this relationship and examine the suggested effects of the negative energy balance on follicular growth. Investigation of these effects was performed on fasted heifers. The experimental treatment consisted of feeding hay with a subsequent period of fasting, to induce elevated plasma NEFA concentrations. Sampling of follicular fluid was performed using transvaginal aspiration of follicles, which were standardized using a synchronization protocol. In addition, concentrations of glucose, insulin, NEFA, and estradiol were measured in plasma. Follicular estradiol and progesterone concentrations were also measured to assess the quality of the dominant follicle. Fasting resulted in significantly lower plasma glucose (P=0.0006) and plasma insulin (P<0.0001) concentrations, higher plasma estradiol (P=0.008) and higher NEFA (P<0.001) concentrations, and smaller follicles (P=0.04) with lower estradiol:progesterone (E/P) ratios (P=0.05). Concentrations of NEFA in follicular fluid and plasma were closely related. Given this close relationship, we concluded that the presence of high plasma NEFA concentrations might link energy metabolism in early lactation with fertility.

Postpartum reproductive function: association with energy, metabolic and endocrine status in high yielding dairy cows

This study evaluated the effect of metabolic, endocrine and energy status on onset of ovarian cycle, days open (DO), and conception at first service in 90 multiparous Holstein cows, housed at a research farm. Dry matter intake, milk yield and body weight were measured daily from Week 2 antepartum (a.p.) to Week 20 postpartum (p.p.). Milk composition was determined four times per week and milk acetone was measured weekly. Blood samples for the determination of glucose, non-esterified fatty acids, cholesterol, creatinine, albumin, urea, beta-hydroxybutyrate, leptin, insulin, insulin-like growth factor-1, growth hormone, 3,5,3'-triiodothyronine (T(3)), and thyroxine (T(4)) were taken 2 weeks a.p., in Weeks 1-16, and 20 p.p. between 7:30 and 9:00 h. The onset of ovarian cycle was specified by weekly gynecological examination and by skim milk progesterone determination by radioimmunoassay (twice per week). Energy balance (EB) traits were calculated and expressed as accumulated negative EB from calving to EB equilibrium, EB nadir (EBN), rate of EB recovery after EBN (EBR), and time from calving to EBN and to EB equilibrium, respectively. The onset of ovarian cycle p.p. was not related to EB. However, a low degree of EBN and a fast EBR were associated with fewer DO, and EB at first service was positively related to conception. High plasma levels of T(3) and T(4) p.p. were associated with an early start of ovarian cycle, and high concentrations of glucose and cholesterol with a short calving to conception interval. Conception at first service was positively related to EB at first service and progesterone concentration 10-13 days after first service. In conclusion, thyroid hormones may play an important role in resumption of ovarian cyclicity p.p., and a good energy status enhances the chance of conception at first service and shortens DO.

Gap junctional intercellular communication of bovine granulosa and thecal cells from antral follicles: effects of luteinizing hormone and follicle-stimulating hormone

Throughout each estrous cycle, the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), are involved in regulation of folliculogenesis. We have shown that LH or FSH affect cellular interactions mediated by gap junctions in bovine granulosa and thecal cells in vitro. To evaluate further the hypothesis that gonadotropins influence gap junctional intercellular communication (GJIC) and expression of gap junctional proteins known as connexins (Cx), throughout antral follicle development, granulosa and thecal cells from large (>10 mm; n = 13), medium (5-10 mm; n = 20), and small (<5 mm; n = 27) follicles were cultured (n = 4 cultures per size) with or without LH, FSH, or LH + FSH for 24 h. GJIC was evaluated (n = 125-150 cells/treatment group) by using the fluorescent recovery after photobleaching technique and laser cytometry. Additionally, Cx43, Cx32, and Cx26 were detected in cultured cells by immunocytochemistry and Cx43 by Western immunoblot analysis. Finally, progesterone production by cultured cells was evaluated by radioimmunoassay. Across all follicles and treatments, GJIC was greater (p < 0.01) for granulosa than thecal cells (4.9 +/- 0.05 vs 3.8 +/- 0.04%/min). For granulosa cells of large and medium follicles, LH and/or FSH did not affect GJIC. For granulosa cells of small follicles, FSH increased (p < 0.05), but LH or LH + FSH had no effect on GJIC. For thecal cells of large follicles, LH increased (p < 0.01) GJIC, whereas FSH or LH + FSH had no effects. For thecal cells of medium and small follicles, LH and/or FSH did not affect GJIC. These results demonstrate that FSH influenced GJIC of granulosa cells from small, but not from medium or large, follicles, and LH influenced GJIC of thecal cells from large, but not from medium or small, follicles. Cx43 was present as punctate staining between granulosa or thecal cells from all cultures, indicating assembled gap junctions. LH + FSH increased (p < 0.05) expression of Cx43 only by thecal cells from large follicles. Cx32 was detected in the perinuclear cytoplasm of cultured granulosa or thecal cells, and in the cytoskeleton of a few cells per culture dish in all sizes of follicles. Cx26 was present in a regular pattern throughout the cytoplasm of granulosa or thecal cells in all sizes of follicles. For granulosa cells from large follicles, progesterone production was stimulated (p < 0.05) with LH or FSH alone but was unaffected by LH + FSH. For granulosa cells from medium and small follicles, progesterone production was unaffected by LH and/or FSH. For thecal cells from all sizes of follicles, LH, FSH, and LH + FSH stimulated (p < 0.05) production of progesterone. These data indicate that LH and FSH influence gap junction function and expression, which likely contributes to the development and maintenance of ovarian follicles.