Luteinizing Hormone Ovulation Research Articles

Gene Expression Profiles of LH, Prolactin and Their Receptors in Female Zi Geese (Anser cygnoides) during Development

The objective of this work was to elucidate the gene expression profiles of luteinizing hormone (LH), prolactin (PRL) and their receptors during the developmental and egg laying stage. The expression of genes encoding pituitary LH and PRL, as well as those for the ovarian LH receptor (LHR) and PRL receptor (PRLR), was determined by quantitative real-time PCR in Zi geese on day 1 and at 1, 2, 3, 4, 5, 6, 7 and 8 months of age, respectively. The expression of LH and LHR fluctuated and increased as the geese aged. The expression of LH was significantly higher at 5 to 8 months of age than in 1 day old geese (P < 0.05). The expression of LHR was higher at 8 months than at 1 day, at 1 to 4 months and at 6 months (P < 0.05). The expression of PRL decreased from day 1, followed by an increase from 3 months, and reached the highest values at 8 months of age in the study. The difference in PRL expression between 7 and 8 months of age was significant (P < 0.05). The expression of PRLR decreased initially and this was followed by a fluctuating increase from 5 months until 8 months of age. The expression of PRLR in 1 to 8 month old geese was significantly lower than at day 1 (P < 0.05). These results suggest that LH and PRLR may play an important role in ovarian development and the egg-laying process in Zi geese.

Oocyte Maturation A story of arrest and release

The release of a mature healthy egg for fertilization is the center of the entire reproductive process. From the time of embryonic development till fertilization, the oocyte undergoes several stop-and-go periods. In most animals, oocytes are held in meiotic arrest in prophase I prior to ovulation. The ovulatory luteinizing hormone (LH) surge promotes the resumption of meiosis of the arrested oocytes and their progression through the second meiotic cycle, only to be arrested again at metaphase II until fertilization. This review addresses the underlying mechanisms involved in maintaining the oocyte in meiotic arrest as well as the signaling pathways responsible for releasing it from the arrested phase just prior to ovulation until the completion of meiosis at the time of fertilization.

Regulation of Innate Immune Function in Bovine Oviduct Epithelial Cells in Culture: The Homeostatic Role of Epithelial Cells in Balancing Th1/Th2 Response

This study aimed to investigate the role of epithelial cells in regulating innate immunity in bovine oviduct epithelial cell (BOEC) culture. We studied the effect of Escherichia coli lipopolysaccharide (LPS) and its interaction with ovarian steroids, estradiol (E2) and progesterone (P4), and luteinizing hormone (LH) at concentrations observed during the preovulatory period on immune responses in BOEC culture. Immunohistochemistry of oviduct tissue showed intensive expression of Toll-like receptor-4 (TLR-4) and TLR-2 in epithelial cells. A dose of 10 ng/ml LPS stimulated TLR-4, cyclooxygenase-2 (COX-2), nuclear factor kappa B inhibitor A (NFKBIA), interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) expression, indicating an early pro-inflammatory response. A dose of 100 ng/ml LPS did not induce expression of these genes but stimulated TLR-2, IL-10,IL-4 and microsomal prostaglandin E synthase-1 (mPGES-1) expression and PGE2 secretion, indicating an anti-inflammatory response. Ovarian steroids and LH completely block LPS (10 ng/ml)-induced TLR-4, IL-1β and TNF-α expression as well as LPS (100 ng/ml)-induced TLR-2 expression. Taken together, this study suggests the existence of an early signaling system to respond to infection in the BOEC. In addition, ovarian steroids and LH may play a critical role in inducing homeostasis and in controlling hyperactive pro-inflammatory responses detrimental to epithelial cells, sperm and the embryo.

Characterization of the estrous cycle in female beluga ( Delphinapterus leucas) using urinary endocrine monitoring and transabdominal ultrasound: Evidence of facultative induced ovulation

Recent, successful application of assisted reproductive technologies in captive beluga has resulted from the extensive study of male beluga reproductive biology. Optimization of assisted reproduction requires additional detailed knowledge of the female estrous cycle. Our specific objectives were to: (1) validate urinary immunoassays for use in this species; (2) elucidate annual ovarian cycle dynamics through the combined use of hormone excretion patterns and transabdominal ultrasound; and (3) establish whether ovulation in this species is spontaneous or induced by male factors. Ovulation was observed in four of 15 estrous cycles monitored in four adult female beluga maintained in a single-sex group. After introduction of a breeding male, ovulation was observed in six of seven estrous cycles. All estrous cycles occurred from March through June. For spontaneous ovulations ( n = 4), the inter-estrous interval was 34 d (range 33–35 d), with a follicular phase length (FPL) of 25 ± 8 d (mean ± SD). For all ovulatory estrous cycles (with and without a breeding male), urinary estrogen conjugates (EC, 15.3 ± 7.9 ng/mg Cr) and ovulatory luteinizing hormone (ovLH, 17.1 ± 6.6 ng/mg Cr) concentrations both peaked on Day 0, and EC concentrations returned to baseline 8 ± 7 d later. For non-conceptive cycles, urinary progestagen (Pg) concentrations increased on Day 0 (3.5 ± 1.7 ng/mg Cr), peaked on Day + 19 (19.7 ± 17.1 ng/mg Cr), and were elevated above baseline for 27 ± 4 d. Preovulatory follicular diameter and circumference on Day −2 ± 2 (range: Day −4 to −1) from peak EC were 2.5 ± 0.7 and 7.8 ± 1.3 cm, respectively. The FPL in non-ovulatory estrous cycles ( n = 11) lasted 24 ± 10 d and EC concentrations gradually declined to baseline over a 21 ± 10 d interval following the EC peak (27.8 ± 28.8 ng/mg Cr). Non-ovulatory estrous cycles were characterized by the absence of an ovLH surge and no concomitant increase in Pg concentrations above baseline excretion; the mean follicular diameter at or near peak EC was 3.1 ± 0.8 cm on Day 2 ±3 d from peak EC (range: −1 to +5 days from peak EC). Overall, these data confirm that captive beluga exhibit reproductive seasonality and demonstrate that the species is a facultative-induced ovulator.

Role of the Double Luteinizing Hormone Peak, Luteinizing Follicles, and the Secretion of Inhibin for Dominant Follicle Selection in Asian Elephants (Elephas maximus)1

Elephants express two luteinizing hormone (LH) peaks timed 3 wk apart during the follicular phase. This is in marked contrast with the classic mammalian estrous cycle model with its single, ovulation-inducing LH peak. It is not clear why ovulation and a rise in progesterone only occur after the second LH peak in elephants. However, by combining ovarian ultrasound and hormone measurements in five Asian elephants (Elephas maximus), we have found a novel strategy for dominant follicle selection and luteal tissue accumulation. Two distinct waves of follicles develop during the follicular phase, each of which is terminated by an LH peak. At the first (anovulatory) LH surge, the largest follicles measure between 10 and 19.0 mm. At 7 ± 2.4 days before the second (ovulatory) LH surge, luteinization of these large follicles occurs. Simultaneously with luteinized follicle (LUF) formation, immunoreactive (ir) inhibin concentrations rise and stay elevated for 41.8 ± 5.8 days after ovulation and the subsequent rise in progesterone. We have found a significant relationship between LUF diameter and serum ir-inhibin level (r(2) = 0.82, P < 0.001). The results indicate that circulating ir-inhibin concentrations are derived from the luteinized granulosa cells of LUFs. Therefore, it appears that the development of LUFs is a precondition for inhibin secretion, which in turn impacts the selection of the ovulatory follicle. Only now, a single dominant follicle may deviate from the second follicular wave and ovulate after the second LH peak. Thus, elephants have evolved a different strategy for corpus luteum formation and selection of the ovulatory follicle as compared with other mammals.

Ovarian Follicular Dynamics During the Luteinizing Hormone Surge in the Bottlenose Dolphin (Tursiops truncatus)

Characterizing the relationship between ovarian follicular dynamics and the luteinizing hormone (LH) surge in the bottlenose dolphin (Tursiops truncatus) requires detailed daily monitoring due to the transitory nature of LH and ovulation. Utilizing conditioned dolphins and non-invasive sampling techniques, such as urine collection and trans-abdominal ultrasound exams, provides the means to accurately monitor these fleeting processes. Urine samples and ultrasound exams used in this study were originally performed for the purposes of artificial insemination and controlled natural breeding. The LH surge was identified by a rapid immunochromatographic assay (ICG), and real-time B-modetrans-abdominal ultrasound imaging was used to identify pre-ovulatory follicles (POF). Increases in urinary progesterone levels along with the disappearance of the POF verified ovulation. This studyfound that POF diameters during the LH surge were 1.942 +/- 0.098 cm (n = 9), and time to disappearance of the POF from the last recorded LH peak sample was 37.475 +/- 12.346 h (n = 6). Peak LH surge levels, based on samples collected 2 to 4 times daily, lasted 6.050 +/- 1.332 h (n = 6). Data suggests that bottlenose dolphins, like many other mammals, have brief ovulatory LH surges followed by ovulation within 48 hours.

Age-related LH surge dysfunction correlates with reduced responsiveness of hypothalamic anteroventral periventricular nucleus kisspeptin neurons to estradiol positive feedback in middle-aged rats

Female reproductive aging in rats is characterized by reduced gonadotropin releasing hormone (GnRH) neuronal activation under estradiol positive feedback conditions and a delayed and attenuated luteinizing hormone (LH) surge. The newly identified excitatory neuropeptide kisspeptin is proposed to be a critical mediator of the pubertal transition and the ovarian steroid-induced LH surge. We previously showed that estradiol induces less kisspeptin mRNA expression in the anterior hypothalamus [anatomical location of anteroventral periventricular nucleus (AVPV)] in middle-aged than in young rats and intrahypothalamic infusion of kisspeptin restores LH surge amplitude in middle-aged females. Thus, reduced kisspeptin neurotransmission may contribute to age-related LH surge abnormalities. This study tested the hypothesis that middle-aged females will also exhibit reduced numbers of kisspeptin immunopositive neurons in the AVPV under estradiol positive feedback conditions. Using immunohistochemistry, we demonstrate that middle-aged females primed with ovarian steroids have fewer AVPV kisspeptin immunopositive neurons than young females. Age did not affect kisspeptin mRNA expression in the pituitary, numbers of kisspeptin immunopositive neurons in the arcuate nucleus, or estradiol-dependent reductions in kisspeptin mRNA expression in the posterior hypothalamus (containing the arcuate nucleus). These data strongly suggest that age-related LH surge dysfunction results, in part, from a reduced sensitivity of AVPV kisspeptin neurons to estradiol and hence decreased availability of AVPV kisspeptin neurons to activate GnRH neurons under positive feedback conditions.

Ovarian Luteinizing Hormone Priming Preceding Follicle-Stimulating Hormone Stimulation: Clinical and Endocrine Effects in Women with Long-Term Hypogonadotropic Hypogonadism

Patients with hypogonadotropic hypogonadism (HH), who may be totally LH deficient, remain the primary clinical model for investigating the physiology of gonadotropin actions on ovarian steroidogenesis and follicular development. Our objective was to investigate the effects of LH pretreatment on subsequent ovarian stimulation with FSH in longstanding HH women. A prospective, self-controlled study was conducted at a university tertiary-care center. Eight HH women (six idiopathic, two surgical) underwent ovarian stimulation with recombinant human (rh)FSH preceded or not by rhLH administration in two separate cycles. In one additional patient with idiopathic HH, pretreatment was conducted with recombinant human chorionic gonadotropin (rhCG) instead of rhLH. Follicular development and serum hormone concentrations throughout LH-FSH and FSH treatment cycles were assessed. Pretreatment with rhLH significantly decreased the mean threshold (daily effective) FSH dose and tended to lower the total amount of FSH required to induce follicular maturation in association with appropriate serum estradiol levels and endometrial thickness. Unexpectedly, in HH women retaining functional pituitary tissue, pretreatment with rhLH evoked a consistent elevation of serum LH levels during FSH administration, an effect that was also induced, even at higher magnitude, by pretreatment with rhCG. In addition to changes in FSH requirements for follicular maturation, pretreatment with rhLH/rhCG evoked unambiguous elevations in serum levels of endogenous LH during FSH treatment in HH patients with preserved pituitary function. This is suggestive of a novel regulatory loop of LH secretion involving gonadotropin-stimulated ovarian factors whose nature and physiological relevance are yet to be disclosed, ovarian-derived kisspeptins being appealing candidates.

Changes in brain mRNA levels of gonadotropin-releasing hormone, pituitary adenylate cyclase activating polypeptide, and somatostatin during ovulatory luteinizing hormone and growth hormone surges in goldfish

In goldfish, circulating LH and growth hormone (GH) levels surge at the time of ovulation. In the present study, changes in gene expression of salmon gonadotropin-releasing hormone (sGnRH), chicken GnRH-II (cGnRH-II), somatostatin (SS) and pituitary adenylate cyclase activating polypeptide (PACAP) were analyzed during temperature- and spawning substrate-induced ovulation in goldfish. The results demonstrated that increases in PACAP gene expression during ovulation are best correlated with the GH secretion profile. These results suggest that PACAP, instead of GnRH, is involved in the control of GH secretion during ovulation. Increases of two of the SS transcripts during ovulation are interpreted as the activation of a negative feedback mechanism triggered by high GH levels. The results showed a differential regulation of sGnRH and cGnRH-II gene expression during ovulation, suggesting that sGnRH controls LH secretion, whereas cGnRH-II correlates best with spawning behavior. This conclusion is further supported by the finding that nonovulated fish induced to perform spawning behavior by prostaglandin F2alpha treatment increased cGnRH-II expression in both forebrain and midbrain, but decreased sGnRH expression in the forebrain.

Miniature Ponies: Similarities and Differences from Larger Breeds in Follicles and Hormones during the Estrous Cycle

Recent direct and indirect comparisons between Miniature ponies and larger breeds during the estrous cycle are reviewed. There were many similarities but profound differences in the Miniature ponies, including (1) greatly reduced follicle population within each of several follicle diameter classifications, (2) smaller number of growing follicles 10 mm or larger per ovulatory wave (1.5 ± 0.3 vs. 5.8 ± 0.9 in Miniature ponies vs. horses), (3) lower incidence of detectable diameter deviation, (4) ovulatory luteinizing hormone (LH) surge that involved three distinct phases, and (5) LH increase and decrease during the early luteal phase that followed the ovulatory surge. Diameter of the preovulatory follicle was smaller in Miniature ponies than in horses, but the difference was slight (38 vs. 44 mm; 14%) when compared with an extreme difference in median body weight (123 vs. 465 kg; 74%). The great reduction in follicle population with only a slight reduction in diameter of the preovulatory follicle in Miniature ponies compared with larger breeds is an important consideration during both experimental and clinical examinations.

Local production of the gonadotropic hormones in the rat ovary

The gonadotropic hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are synthesized by and released from the anterior pituitary in response to the hypothalamic gonadotropin-releasing hormone (GnRH) signaling. In the female, LH and FSH affect folliculogenesis, ovarian steroid production, oocyte maturation, ovulation and corpus luteum formation. We have recently studied the expression of GnRH and its receptor in the rat ovary and found organ-specific, estrous cycle-dependant, fluctuations. Subsequently, we wished to determine whether rat ovaries also express gonadotropic hormones. Using RT-PCR, we detected LHβ, FSHβ and the common α-subunit mRNA's in intact follicles, theca cells, corpora lutea and in meiotically competent and incompetent oocytes. Granulosa cells, however, express mRNA's for LHβ and the common α-subunit, but not for FSHβ. We cloned and sequenced the ovarian LHβ transcript and found it to be longer (2.3 kb) than the one produced by pituitary gonadotropes (0.8 kb), due to a longer 5′-UTR. We studied the regulation of ovarian LHβ mRNA in sexually immature female rats administered with pregnant mare serum gonadotropin (PMSG) and in adult cyclic rats. PMSG administration caused a significant decrease in LHβ mRNA expression, detected by real-time PCR. Similarly, LHβ mRNA levels were lower on estrous morning versus proestrous evening. Interestingly, ovarian content of LH remained unchanged following hypophysectomy, although ovarian weight was immensely reduced. Taken together, it seems probable that ovarian LH is heterologously/homologously regulated by pituitary, and possibly also by local gonadotropins. Thus, these findings may imply the existence of a local GnRH–gonadotropin axis in the mammalian ovary that may be involved in the management of processes that lead to ovulation.

Negative Effect of Estradiol on Luteinizing Hormone Throughout the Ovulatory Luteinizing Hormone Surge in Mares1

The negative effect of estradiol-17beta (E2) on LH, based on exogenous E2 treatments, and the reciprocal effect of LH on endogenous E2, based on hCG treatments, were studied throughout the ovulatory follicular wave during a total of 103 equine estrous cycles in seven experiments. An initial study developed E2 treatment protocols that approximated physiologic E2 concentrations during the estrous cycle. On Day 13 (ovulation = Day 0), when basal concentrations of E2 and LH precede the ovulatory surges, exogenous E2 significantly depressed LH concentrations to below basal levels. Ablation of all follicles > or = 10 mm when the largest was > or =20 mm resulted in an increase in percentage change in LH concentration within 8 h that was greater (P < 0.03) than for controls or E2-treated/follicle-ablated mares. Significant decreases in LH occurred when E2 was given when the largest follicle was either > or =25 mm, > or =28 mm, > or =35 mm, or near ovulation. Treatment with 200 or 2000 IU of hCG did not affect E2 concentrations during the initial portion of the LH surge (largest follicle, > or =25 mm), but 2000 IU significantly depressed E2 concentrations before ovulation (largest follicle, > or =35 mm). Results indicated a continuous negative effect of E2 on LH throughout the ovulatory follicular wave and may be related to the long LH surge and the long follicular phase in mares. Results also indicated that a reciprocal negative effect of LH on E2 does not develop until the E2 surge reaches a peak.

Insulin and Not Human Chorionic Gonadotropin is Significantly Correlated with Total Testosterone and Free Testosterone in Pregnancies Affected by Gestational Diabetes

Background and Significance: Previous studies have demonstrated increased levels of maternal serum androgens in pregnancies affected by gestational diabetes (GDM). The mechanism behind this is unclear, but may be similar to that which is seen in polycystic ovarian syndrome (PCOS), where hyperinsulinemia causes hyperandrogenemia. Another possible mechanism could involve human chorionic gonadotropin (hCG) cross-reacting with ovarian luteinizing hormone receptor. Finally, obesity, which is commonly associated with GDM, may play a significant role in androgen production.

Extracellular Matrix of the Cumulus-Oocyte Complex

The mammalian oocyte is surrounded by several layers of cumulus granulosa cells that nurture the oocyte during its development and actively participate in the process of ovulation. After the ovulatory luteinizing hormone surge, a distinctive program of extracellular matrix production is initiated in the cumulus-oocyte complex. This process known as cumulus expansion or mucification involves synthesis of a backbone of long hyaluronan oligosaccharide chains that are cross-linked by a complex of hyaluronan binding cell surface and extracellular matrix proteins and proteoglycans. Active components of the cumulus matrix are synthesized directly by cumulus cells under the control of endocrine- and oocyte-derived factors, secreted by mural granulosa cells, or enter the follicle in blood plasma. Appropriate composition and assembly of the cumulus matrix is essential for ovulation, efficient passage of the oocyte through the oviduct, and for fertilization. This review describes the critical components and their functional roles in the cumulus matrix, as well as the molecular regulation of cumulus matrix gene expression.

Changes in ovarian steroidogenesis in insulin-resistant, type 2 diabetic Goto–Kakizaki rats after thyroidectomy and gonadotropin treatment

The present study used thyroidectomized insulin-resistant, type 2 diabetic Goto–Kakizaki (GK) rats to assess whether insulin resistance and hypothyroidism modulate ovarian physiology. Animals were treated with daily injections of 5 IU equine chorionic gonadotropin for 5 days starting 1 week after thyroidectomy. Control groups included rats of GK and control (Wistar) strains treated only with equine chorionic gonadotropin or thyroidectomy, or with no treatment (intact). In Wistar rats, equine chorionic gonadotropin injections tended to increase the serum concentrations of luteinizing hormone (LH) and testosterone more in the thyroidectomy group than in intact rats. Similar changes in LH and testosterone were observed in the thyroidectomy + equine chorionic gonadotropin and equine chorionic gonadotropin groups of GK rats, but the LH and testosterone levels in the thyroidectomy + equine chorionic gonadotropin group were significantly higher in GK rats. Expression of ovarian LH receptor messenger RNA (mRNA) was enhanced by thyroidectomy. The LH receptor mRNA levels were significantly higher in the thyroidectomy + equine chorionic gonadotropin group of GK rats than in the corresponding group of control rats. These results indicate that hypothyroidism in animals with insulin resistance and type 2 diabetes promotes LH and testosterone secretions, and suggests that the enhanced-testosterone levels is partially mediated by the enhancement of LH receptor expression and an increase in the serum level of LH.

Effect of Troglitazone on the Excess Testosterone and LH Secretion in Thyroidectomized, Insulin-Resistant, Type 2 Diabetic Goto–Kakizaki Rats

Our previous study suggested that hypothyroidism in Goto-Kakizaki (GK) rats with insulin resistance and type 2 diabetes elevates their serum testosterone and luteinizing hormone (LH) levels and ovarian LH receptor messenger RNA (mRNA) expression. The present study assessed the effects of troglitazone (Tro), an insulin-sensitizing agent, on these hypothyroidism-induced hormonal changes in GK rats. GK and normal (Wistar strain) female rats were thyroidectomized (Tx) and then injected with 5 IU of equine chorionic gonadotropin (eCG) for 5 d starting 1 wk after thyroidectomy (the control groups). In the test groups, Tx GK and Wistar rats were injected with both eCG and Tro (100 mg kg-1) po for 5 d. Tro treatment had no effect on the elevated LH serum levels in eCG-treated Tx GK rats but suppressed their enhanced serum testosterone levels as well as significantly decreasing their LH receptor mRNA expression. Tro lowered testosterone and LH receptor mRNA levels in cultured theca cells. These results indicate that Tro lowers the elevated testosterone secretion and ovarian LH receptor mRNA expression that is induced in GK rats by Tx and gonadotropin treatment, which suggests that insulin resistance may be involved in enhancing testosterone production and LH receptor expression in the ovary.

NMDA receptors in the medial zona incerta stimulate luteinizing hormone and prolactin release.

1. The aim of the present work is to demonstrate the interaction between the glutamatergic/NMDA and dopaminergic systems in the medial zona incerta on the control of luteinizing hormone and prolactin secretion and the influence of reproductive hormones. 2. Proestrus and ovariectomized rats were primed with estrogen and progesterone to induce high or low levels of luteinizing hormone and prolactin. 2-Amino-7-phosphonoheptanoic acid, an NMDA receptor antagonist, and dopamine were injected in the medial zona incerta. Blood samples were withdrawn every hour between 1,600 and 2,000 hours or 2,200 hours via intracardiac catheter from conscious rats. Additional groups of animals injected with the NMDA receptor antagonist were killed 1 or 4 h after injection. Dopamine and its metabolite 3,4-dihydroxyphenylacetic acid were measured in different hypothalamic regions. 3. 2-Amino-7-phosphonoheptanoic acid blocked the ovulatory luteinizing hormone surge in proestrus rats. 2-Amino-7-phosphonoheptanoic acid also blocked the increase in luteinizing hormone induced by ovarian hormones in ovariectomized rats, an effect that was partially reversed by dopamine injection. Conversely, the increased release of luteinizing hormone and prolactin induced by dopamine was prevented by 2-amino-7-phosphonoheptanoic acid. We found that the NMDA antagonist injection decreased the dopaminergic activity--as evaluated by the 3,4-dihydroxyphenylacetic acid/dopamine ratio--in the medio basal hypothalamus and increased in the preoptic area. 4. Our results show an stimulatory role of NMDA receptors on the ovulatory luteinizing hormone release and on luteinizing hormone release induced by sexual hormones and demonstrate that the stimulatory effect of dopamine on luteinizing hormone and prolactin is mediated by the NMDA receptors. These results suggest a close interaction between the glutamatergic and dopaminergic incertohypothalamic systems on the control of luteinizing hormone and prolactin release.

Processing and Localization of ADAMTS-1 and Proteolytic Cleavage of Versican during Cumulus Matrix Expansion and Ovulation

ADAMTS-1 (a disintegrin and metalloprotease with thrombospondin motifs-1) is a member of the ADAMTS family of metalloproteases which, together with ADAMTS-4 and ADAMTS-5, has been shown to degrade members of the lectican family of proteoglycans. ADAMTS-1 mRNA is induced in granulosa cells of periovulatory follicles by the luteinizing hormone surge through a progesterone receptor-dependent mechanism. Female progesterone receptor knockout (PRKO) mice are infertile primarily due to ovulatory failure and lack the normal periovulatory induction of ADAMTS-1 mRNA. We therefore investigated the protein localization and function of ADAMTS-1 in ovulating ovaries. Antibodies against two specific peptide regions, the pro-domain and the metalloprotease domain of ADAMTS-1, were generated. Pro-ADAMTS-1 of 110 kDa was identified in mural granulosa cells and appears localized to cytoplasmic secretory vesicles. The mature (85-kDa pro-domain truncated) form accumulated in the extracellular matrix of the cumulus oocyte complex (COC) during the process of matrix expansion. Each form of ADAMTS-1 protein increased >10-fold after the ovulatory luteinizing hormone surge in wild-type but not PRKO mice. Versican is also localized selectively to the ovulating COC matrix and was found to be cleaved yielding a 70-kDa N-terminal fragment immunopositive for the neoepitope DPEAAE generated by ADAMTS-1 and ADAMTS-4 protease activity. This extracellular processing of versican was reduced in ADAMTS-1-deficient PRKO mouse ovaries. These observations suggest that one function of ADAMTS-1 in ovulation is to cleave versican in the expanded COC matrix and that the anovulatory phenotype of PRKO mice is at least partially due to loss of this function.

Presence of κ-opioid tone at the onset of the ovulatory luteinizing hormone surge in the proestrous rat

A decrease in endogenous opioid peptide inhibitory tone on the afternoon of proestrus is one event underlying generation of the ovulatory luteinizing hormone (LH) surge. Whether this disinhibition involves a complete loss of opioid suppression at the time of the LH surge is controversial. The objective of the present study was to determine whether a total loss specifically of the κ-opioid inhibitory component suppressing LH secretion occurs on proestrus at the onset of the LH surge. Proestrous rats were infused intraventricularly with either artificial cerebrospinal fluid (aCSF) or aCSF containing nor-binaltorphimine (nor-BNI), a selective κ-opioid receptor antagonist, from 15:30 or 16:30 h (the approximate onset time of the spontaneous LH surge) to 18:50 h. The LH surge in rats treated with nor-BNI beginning at 15:30 h started 0.5 h earlier than the spontaneous surge in aCSF controls, and had significantly higher plasma LH levels from 16:30 to 17:30 h. Nor-BNI administration begun at 16:30 h also produced an LH surge with more elevated plasma LH levels at 17:30 and 18:00 h than in aCSF-treated controls. These results demonstrate that significant amounts of κ-opioid tone are still present during the hours when the LH surge is initiated. Thus, a complete loss of κ-opioid inhibition is not required for the onset of the LH surge on proestrus.

Estrogen and LH dynamics during the follicular phase of the estrous cycle in the Asian elephant

AbstractPituitary and corpus luteum hormone patterns throughout the elephant estrous cycle have been well characterized. By contrast, analysis of follicular maturation by measurement of circulating estrogens has been uninformative. This study tested the ability of a urinary estradiol‐3‐glucuronide radioimmunoassay to noninvasively assess follicular development during the nonluteal phase of the elephant estrous cycle, and to determine the relationship between estrogen production and the “double LH surge.” Daily urine and serum samples were collected throughout seven estrous cycles from three Asian elephants, and urine was collected from an additional three females, for a total of 13 cycles. Serum was analyzed for luteinizing hormone (LH), and urine was analyzed for estrogens and progestins. Elephants exhibited a typical LH pattern, with an anovulatory LH (anLH) surge occurring approximately 21 days before the ovulatory LH (ovLH) surge. The urinary estrogen pattern indicated the presence of two follicular waves during the nonluteal phase. The first wave (anovulatory) began 5 days before the anLH surge and reached a maximum concentration the day before the peak. Thereafter, urinary estrogens declined to baseline for 2 weeks before increasing again to peak concentrations on the day of the ovLH surge. Urinary progestins were baseline throughout most of the follicular phase, increasing 2–3 days before the ovLH surge and continuing into the luteal phase. These results support previous ultrasound observations that two waves of follicular growth occur during the nonluteal phase of the elephant estrous cycle. Each wave is associated with an increase in estrogen production that stimulates an LH surge. Thus, in contrast to serum analyses, urinary estrogen monitoring appears to be a reliable method for characterizing follicular activity in the elephant. Zoo Biol 22:443–454, 2003. © 2003 Wiley‐Liss, Inc.