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LH Peak (lh + peak)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Timing of Preovulatory LH Surge and Ovulation in Superovulated Sheep are Affected by Follicular Status at Start of the FSH Treatment

REPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2008
A Veiga-Lopez
Contents The aims of this study were to evaluate the chronology of periovulatory events (oestrus behaviour, LH surge and ovulation) in 16 superovulated Manchega sheep and to determine whether follicular status at start of the FSH supply might affect their occurrence. Mean timing for onset of oestrus behaviour was detected at 28.1 ± 0.7 h after sponge withdrawal; the preovulatory LH surge and ovulation started at 37.2 ± 0.7 h and 65.4 ± 0.7 h after progestagen withdrawal, respectively. The intervals between oestrus, LH surge and ovulation were affected by a high individual variability, which might be the cause for reported decreased efficiency in embryo production. Current results also addressed the role of follicular status at start of the superovulatory treatment on the preovulatory LH surge and the ovulation. The interval LH surge-ovulation was increased in ewes with a growing dominant follicle at starting the FSH treatment (32.3 ± 0.9 vs 28.6 ± 0.5 h, p < 0.05). The developmental stage of the largest follicle at starting the superovulatory treatment also affected occurrence of LH surge and ovulation; follicles in growing phase advanced the occurrence of the LH surge and ovulation when compared to decreasing follicles (33.0 ± 1.0 vs 43.5 ± 1.1 h, p < 0.05, for LH peak and 60.7 ± 1.1 vs 72.8 ± 1.2 h, p < 0.05, for ovulation). Thus, only ewes with growing follicles ovulated prior to 55 h after sponge withdrawal; conversely, no sheep with decreasing follicles ovulated earlier than 67 h, when an 85.7% of the ewes bearing growing follicles has ovulated at 63 h. [source]

Investigations on the Re-establishment of the Positive Feedback of Oestradiol during Anoestrus in the Bitch

REPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2003
R Klein
Contents To test for the re-establishment of the positive feedback of oestradiol (E2) during anoestrus in the dog, the hypothalamo,pituitary,ovarian axis of five beagle bitches was challenged by treatments with oestradiol benzoate (EB), mimicking the course of the pro-oestric E2 secretion. Treatments in anoestrus started 7 days following the decline of progesterone (P) <1 ng/ml; they were repeated in 5 week intervals until onset of pro-oestrus; another treatment was performed during dioestrus 50 days after onset of the preceding pro-oestric bleeding. Each dog served as its own control by receiving vehicle-treatments in one of the following cycles. Each observation period covered a time window of 168 h and blood samples were collected for the determination of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and E2 in 6 (0,24 h) and 8 h (24,168 h) intervals. In the control periods and as indicated by the parameters area under curve (AUC), basal and maximal values, the availability of LH, FSH and E2 decreased from dioestrus to early anoestrus to increase again during the course of anoestrus (p < 0.05), indicating a gradual desensitization of the hypothalamus towards the negative feedback of oestradiol. At all times treatments with EB lowered the availability of FSH (decreased AUC and basal levels). A delay in the occurrence of the first LH peak after treatments with EB (p < 0.001) and decreased maximal values (p < 0.001) indicated a suppression of the LH-release. In no case treatment with EB led to a pre-ovulatory like LH-surge. In each dog the last trial with EB in anoestrus passed over into pro-oestrus/oestrus, with a reduced AUC and peak value of the pre-ovulatory LH-surge being the only differences to the control group. The observed differences in the response of LH and FSH to treatments with EB point towards subtle differences in the mechanisms controlling the release of these two hormones during anoestrus. From the data obtained, it may be concluded that the time window for E2 to act via a positive feedback seems to be very small and restricted to the end of anoestrus, and that full follicular function is a pre-requisite to allow for this phenomenon. [source]

Measurement of urinary and fecal steroid metabolites during the ovarian cycle in captive and wild Japanese macaques, Macaca fuscata

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2001
Shiho Fujita
Abstract We measured the concentration of steroid hormones from urine, feces, and blood samples of two captive Japanese macaques, Macaca fuscata, during nonconceptive ovarian cycles to compare the patterns of the excreted steroids with those of circulating steroids. Urine and feces were analyzed for estrone conjugates (E1C) and pregnanediol-3-glucronide (PdG) using enzyme immunoassays (EIAs), while plasma was analyzed for estradiol-17,(E2), progesterone (P), and luteinizing hormone (LH) using radioimmunoassays (RIAs). Urinary and fecal E1C and PdG levels were approximately parallel to plasma E2 and P levels, respectively. The E1C profiles of daily urinary and fecal samples revealed a midcycle peak, followed by a sustained PdG increase lasting up to two weeks from the E1C peak. A fecal E1C peak was one day later than the urinary E1C peak. One of the captive females exhibited a discrete plasma LH peak, one indicator that ovulation has occurred, on the day following the urinary E1C peak, i.e., the same day of fecal E1C peak. We measured excreted steroids in nine wild females and determined the timing of ovulation by comparing fecal steroid profiles to those obtained in captive monkeys. Data from wild females indicated that eight of nine females conceived during their first ovulatory cycle of the sampling period, whereas the remaining female failed to conceive during the sampling period even though she ovulated. In the eight females that conceived, E1C increased again following the detected or estimated E1C peak, with levels comparable to the preovulatory peak levels, and sustained elevations of PdG for over 40 days. These data illustrate that the urinary and fecal profiles of ovarian steroid excretion obtained through the application of these noninvasive techniques provide an accurate approach for monitoring conceptive and nonconceptive ovarian cycle in captive and free-living Japanese macaques. Am. J. Primatol. 53:167,176, 2001. © 2001 Wiley-Liss, Inc. [source]

Comparison of three doses of leuprolide acetate in the treatment of central precocious puberty: preliminary results

CLINICAL ENDOCRINOLOGY, Issue 5 2009
Verónica Mericq
Summary Objective, Depot luteinizing-hormone releasing hormone (LHRH) agonist have been widely used for the treatment of central precocious puberty (CPP), but the optimal doses to obtain hormonal suppression are still unknown, especially in patients with higher weights. The goal of our study was to compare the efficacy of three leuprolide acetate (LA) preparations, suppressing gonadotropin secretion in patients with CPP. Design, In an open 12-month protocol, we evaluated LA 7·5 mg/month, 11·25 and 22·5 every 3 months. Patients, Fourteen girls with CPP and weights over 30 kg. Measurements: Clinical, radiological and laboratory follow-up: GnRH test plus LH, FSH 40 min post analogue was performed periodically. Results, Pretreatment basal and LHRH stimulated LH levels between groups were not different. Basal and LHRH stimulated LH levels decreased significantly between baseline and from 3 up to 12 months of therapy in all groups (P = 0·001). GnRH stimulated LH peak <2 IU/l, the main efficacy criterion was met in 80, 75 and 100% of the children at 6 months in the 7·5, 11·25, 22·5 mg doses respectively. By 12 months, 100% of patients had LH suppressed to <2 IU/l. Conclusions These results affirm that 3-month injections may be a satisfactory alternative for the therapy of children with CPP to avoid monthly injections. In addition, suppression of LH occurs sooner in the 3-month 22·5 mg LA dose compared to the 3-month 11·5 mg; therefore, adequate dosing may be important for optimal outcome. Further investigation is needed in more patients over 30 kg, with longer treatment duration, and ultimately final height consideration. [source]