Biomedical subjects
Publications and source records attributed to G Cognigni.
Pulsatile gonadotropin secretion is a critical endocrine component of the regulation of the normal menstrual cycle. Pulsatile luteinizing hormone (LH) secretion changes dynamically across the menstrual cycle. Derangements of pulsatile LH secretion are found in virtually every menstrual disorder. This article summarizes the key features of pulsatile LH secretion in the normal menstrual cycle and in ovulatory disorders.
OBJECTIVE: To assess the oral glucose tolerance test (OGTT)-stimulated insulin secretion and its relation to pulsatile GnRH ovulation induction outcome in patients with multifollicular or polycystic ovaries (PCOs). DESIGN: Prospective study. SETTING: Reproductive Endocrinology Center, University of Bologna, Bologna, Italy. PATIENTS: Eight normal and 29 anovulatory women (8 with multifollicular ovaries and 21 with PCOs). INTERVENTION: A standard OGTT was performed in all subjects. In all anovulatory patients, ovulation was induced with pulsatile GnRH (5 micrograms i.v. every 60 minutes). In multifollicular ovary patients, pulsatile GnRH was administered alone, whereas in PCOs it was preceded by GnRH agonist (GnRH-a) suppression. MAIN OUTCOME MEASURES: Glucose, insulin, and C-peptide response to the OGTT, expressed as area under the curve (AUC). Ovulatory rates in response to pulsatile GnRH. RESULTS: Insulin and C-peptide AUC were greater than controls in both multifollicular ovary and PCO patients. Insulin AUC was positively correlated to ovarian volume. Ovulation was achieved in 88% and 57% of multifollicular ovary and PCO patients, respectively. Body mass index and glucose AUC but not insulin and C-peptide AUC were significantly greater in the anovulatory PCO. CONCLUSIONS: [1] Insulin AUC was increased in both multifollicular ovary and PCO patients; [2] derangements of insulin secretion may be present in a greater variety of anovulatory patients than previously thought; [3] insulin levels during the OGTT did not predict a response to pulsatile GnRH in PCOs, suggesting complex insulin interactions at the ovarian level; [4] given the in vitro stimulatory properties of insulin on granulosa cells synergistic with FSH, we propose that excessive insulin levels may contribute to the ovarian enlargement often found in multifollicular ovary and PCO patients.
Pulsatile GnRH (pGnRH) was administered to 292 anovulatory patients in 600 consecutive cycles between February 1984 and February 1993. This represents the largest single pGnRH series ever reported. Patients were divided into the following groups: primary hypogonadotropic amenorrhea (PHA), 73 patients, 161 cycles; other hypogonadotropic hypogonadisms (OHH), 57 patients 107 cycles; multifollicular ovary (MFO), 39 patients 75 cycles; polycystic ovary (PCO), 85 patients 172 cycles; and other hyperandrogenic anovulations (OHA), 38 patients 85 cycles. GnRH was administered iv at a dose of 1.25-20.0 micrograms every 30-120 min; most cycles (505) were performed with a regimen of 2.5-5.0 micrograms GnRH every 60-90 min. In 228 cycles of MFO, PCO, and OHA patients, pGnRH was preceded by GnRH agonist (GnRH-A) suppression. Ovulatory rates were 75%, and pregnancy occurred in 105 cycles (pregnancy rate of 18%/treatment cycle and 23%/ovulatory cycle). Ovulatory and pregnancy rates were higher in PHA, OHH, and MFO and lower in PCO and OHA. Only 4 multiple pregnancies occurred (3.8%), none after GnRH-A suppression. The abortion rate was 30% and was highest in PCO (45%). GnRH-A pretreatment improved ovulatory rates only in PCO (from 49% to 71%; P < 0.001), whereas it had no significant effect on pregnancy and abortion rates in any group. Higher weight and insulin were associated with lower ovulatory and pregnancy rates; higher LH and testosterone were associated with lower ovulatory rates only. We conclude that 1) pGnRH is a highly effective ovulation induction method; 2) pGnRH does not cause ovarian hyperstimulation; 3) low dose pGnRH is associated with a remarkably low incidence of multiple pregnancy; 4) GnRH-A pretreatment improves pGnRH outcome in PCO and further lowers the incidence of multiple pregnancy; 5) pGnRH is associated with relatively elevated abortion rates, particularly in PCO; and 6) pGnRH is less successful in overweight patients and when high baseline LH, testosterone, and insulin levels are present.
The pattern of episodic gonadotrophin releasing hormone (GnRH)-driven luteinizing hormone (LH) secretion changes dynamically across the human menstrual cycle. Adherence to a specific regimen of pulse amplitude and frequency is critical for normal ovulation, menstrual cyclicity and reproductive function. Derangements of episodic LH secretion are associated with anovulation. We have shown that in the human slowing of GnRH-induced LH pulses results in lower ovulatory rates and dysfunctions of the mid-cycle LH surge. This information is relevant for the understanding of the endocrine dynamics of the menstrual cycle both in normal and anovulatory subjects.
Different depot GnRH analogs (GnRH-A) are currently used for the reversible suppression of the pituitary-ovarian axis in several reproductive and neoplastic disorders in women. In spite of anecdotal reports of incomplete suppression by some depot GnRH-A, this issue has never been systematically investigated in adult women. Thus, we elected to study 40 normally cycling women with male-related infertility or benign reproductive disorders; each group of 10 subjects received a different GnRH-A for 3 months: buserelin (group B; 300 micrograms, sc, every 12 h, as a control), goserelin (group G; 3.6 mg, sc, every 28 days), leuprorelin (group L; 3.75 mg, im, every 28 days), and triptorelin (group T; 3.75 mg, im, every 28 days). Depot GnRH-A was administered by one of the investigators. GnRH tests (100 micrograms, iv) were performed before treatment (cycle day 7; test A) and on treatment days 57 (i.e. 1 day after the third depot GnRH-A; test B) and 84 (i.e. 28 days after the third depot GnRH-A; test C). Immunoreactive (i) LH levels were measured with an ultrasensitive immunochemiluminometric assay. Profound suppression of the iLH response to the GnRH test occurred in all subjects during treatment. Conversely, FSH levels in the third month of treatment tended to be higher in the depot GnRH-A groups than in group B, and this difference achieved statistical significance (P < 0.05) in groups G and L during test C. In GnRH test B, while the mean estradiol (E2) level was less than 75 pmol/L (< 20 pg/mL) in all group B subjects, individual E2 levels were greater than 75 pmol/L in five patients receiving depot GnRH-A (two in group G, one in L, and two in T). Finally, individual E2 levels during test C were greater than 75 pmol/L in only two patients of group G, who also reported vaginal spotting. Thus, we conclude that in adult women, 1) iLH was profoundly suppressed in the third month of administration of all GnRH-A tested; 2) FSH suppression with depot GnRH-A was less marked than that with high-dose short-acting sc buserelin; and 3) signs of an incomplete block of ovarian function can be present in the third month of depot GnRH-A administration, particularly when goserelin is employed.
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To accrue systematic information in different ovulatory disorders on the precise relationship among endocrine response, clinical outcome, and the occurrence of complications, we treated 114 patients with pulsatile GnRH (2.5-5.0 micrograms, iv, every 60 min) for 187 cycles and compared them to 20 normal menstrual cycles. Thirty of these patients had primary hypogonadotropic amenorrhea (PHA; 40 cycles), 33 had other forms of hypogonadotropic hypogonadism (HH; 55 cycles), and 51 had polycystic ovary syndrome (PCOS; 92 cycles). Daily blood samples were drawn for hormone determinations. In PCOS, 50 cycles were preceded by GnRH analog suppression. PHA treatment cycles were characterized by the reestablishment of a normal endocrine pattern, almost no dose-related endocrine differences, elevated ovulatory (93%) and conception rates (23%), and no multiple pregnancies. In the HH subjects the ovulatory (91%) and pregnancy rates (31%) were high; however, while the lower GnRH dose elicited a normal endocrine pattern, the 5-micrograms dose induced excessive folliculogenesis and high estradiol levels and was associated with most of the multiple pregnancies of this study (three of four). GnRH analog suppression was successfully used to avoid recurrence of ovarian over-stimulation in two HH subjects. Finally, GnRH analog suppression in PCOS permitted normalization of the follicular phase endocrine pattern, achievement of good ovulatory (76%) and pregnancy (28%) rates, and avoidance of multiple pregnancies; however, luteal phase steroid secretion was abnormal, and the abortion rate remained elevated (43%). Obesity was associated with a reduced ovulatory rate in PCOS, but not in hypogonadotropic, subjects. Thus, we can conclude that in pulsatile GnRH ovulation induction: 1) a profound hypogonadotropic condition, whether spontaneous as in PHA or induced with GnRH analogs as in other ovulatory disorders, is associated with optimal menstrual cycle restoration, high ovulatory and conception rates, and virtually absent risks of multiple pregnancy; 2) residual hypothalamic activity in HH may be responsible for supraphysiological pituitary-ovarian stimulation and result in multiple pregnancy unless a low GnRH dose (2.5 micrograms/bolus) or GnRH analog pretreatment is employed; 3) obesity does not affect treatment outcome in hypogonadotropic patients; and 4) the high spontaneous abortion rate in PCOS may be related to corpus luteum dysfunction.