Impact of leuprolide acetate on the response to follicular stimulation for in vitro fertilization in patients with normal basal gonadotropin levels

Animal models of transcranial direct current stimulation: Methods and mechanisms

The objective of this review is to summarize the contribution of animal research using direct current stimulation (DCS) to our understanding of the physiological effects of transcranial direct current stimulation (tDCS). We comprehensively address experimental methodology in animal studies, broadly classified as: (1) transcranial stimulation; (2) direct cortical stimulation in vivo and (3) in vitro models. In each case advantages and disadvantages for translational research are discussed including dose translation and the overarching "quasi-uniform" assumption, which underpins translational relevance in all animal models of tDCS. Terminology such as anode, cathode, inward current, outward current, current density, electric field, and uniform are defined. Though we put key animal experiments spanning decades in perspective, our goal is not simply an exhaustive cataloging of relevant animal studies, but rather to put them in context of ongoing efforts to improve tDCS. Cellular targets, including excitatory neuronal somas, dendrites, axons, interneurons, glial cells, and endothelial cells are considered. We emphasize neurons are always depolarized and hyperpolarized such that effects of DCS on neuronal excitability can only be evaluated within subcellular regions of the neuron. Findings from animal studies on the effects of DCS on plasticity (LTP/LTD) and network oscillations are reviewed extensively. Any endogenous phenomena dependent on membrane potential changes are, in theory, susceptible to modulation by DCS. The relevance of morphological changes (galvanotropy) to tDCS is also considered, as we suggest microscopic migration of axon terminals or dendritic spines may be relevant during tDCS. A majority of clinical studies using tDCS employ a simplistic dose strategy where excitability is singularly increased or decreased under the anode and cathode, respectively. We discuss how this strategy, itself based on classic animal studies, cannot account for the complexity of normal and pathological brain function, and how recent studies have already indicated more sophisticated approaches are necessary. One tDCS theory regarding "functional targeting" suggests the specificity of tDCS effects are possible by modulating ongoing function (plasticity). Use of animal models of disease are summarized including pain, movement disorders, stroke, and epilepsy.

Prospective evaluation of two stimulation protocols for low responders who were undergoing in vitro fertilization-embryo transfer

OBJECTIVE

To compare two stimulation protocols designed for low responders undergoing IVF.

DESIGN

Randomized, prospective study.

SETTING

University hospital IVF unit.

PATIENT(S)

Sixty low responders who were recruited on the basis of results in previous cycles.

INTERVENTION(S)

Modified flare protocol in which a high dose of GnRH agonist was administered for the first 4 days, followed by a standard agonist dose, or a modified long protocol in which a standard agonist dose was used until pituitary down-regulation, after which the agonist dose was halved during stimulation.

MAIN OUTCOME MEASURE(S)

Number of oocytes retrieved.

RESULT(S)

Twenty-nine cycles were performed with the modified flare protocol and 31 were performed with the modified long protocol. Significantly more oocytes were obtained with the modified long protocol than the modified flare protocol (4.42 +/- 2.6 vs. 3.07 +/- 2.15). The number and quality of embryos available for transfer was similar in both groups. One clinical pregnancy (3.4%) was achieved with the modified flare protocol, and 7 pregnancies (22.5%) were achieved using the modified long protocol.

CONCLUSION(S)

These preliminary results substantiate the poor prognosis and outcome for low responders undergoing IVF. A modified long "mini-dose" protocol appears to be superior to a modified mega-dose flare protocol in terms of oocyte yield and cycle outcome.

Leuprorelin. A review of its pharmacology and therapeutic use in prostatic cancer, endometriosis and other sex hormone-related disorders

Leuprorelin (leuprolide acetate) is a gonadotrophin-releasing hormone (GnRH) analogue used to treat a wide range of sex hormone-related disorders including advanced prostatic cancer, endometriosis and precocious puberty. It acts primarily on the anterior pituitary, inducing a transient early rise in gonadotrophin release. With continued use, leuprorelin causes pituitary desensitisation and/or down-regulation, leading to suppressed circulating levels of gonadotrophins and sex hormones. Clinical trials in men with advanced prostatic cancer demonstrate that leuprorelin (usually monthly depot injections of 3.75 or 7.5 mg) is less likely to cause serious adverse cardiovascular effects than diethylstilbestrol, and has comparable efficacy to bilateral orchiectomy or other GnRH analogues. Therefore, the choice between leuprorelin and orchiectomy may be made on the basis of the patient's treatment preference, along with specific patient characteristics and cost implications. Monthly intramuscular or subcutaneous administration of depot leuprorelin 3.75 mg was superior to placebo, and comparable to oral danazol 800 mg/day or intranasal buserelin 900 micrograms/day, in achieving objective and subjective responses in women with endometriosis. Thus, leuprorelin is an effective alternative to other treatments for women with endometriosis, but the recommended duration of its use in this clinical setting is limited to 6 months because it reduces bone mineral density. In children with central precocious puberty, leuprorelin (usually monthly intramuscular or subcutaneous injections of depot leuprorelin 3.75 to 15mg) decreases mean growth velocity and signs of sexual maturation and increases predicted adult height compared with baseline measurements. Although effects on final adult height are predicted from available data and require confirmation in long term follow-up studies, the absence of effective alternatives to GnRH analogues makes leuprorelin a first-line therapy for children with this rare disease. In women with uterine leiomyomata, monthly intramuscular administration of depot leuprorelin 3.75 mg for 6 months markedly reduces uterine volume and fibroid-related symptoms, but, as with other GnRH analogues, these effects dissipate following discontinuation of the drug. As adjuvant therapy in women undergoing in vitro fertilisation or gamete intrafallopian transfer, leuprorelin (usually 0.5 to 1 mg/day subcutaneously) reduces the risk of cancelled cycles for oocyte retrieval by preventing premature luteinisation. While some studies demonstrate an improvement in intermediate end-points such as increased number of mature oocytes retrieved and embryos available for transfer, a significant effect has not been demonstrated on the rate of live births per stimulated cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Performance of cryopreserved pre-embryos obtained in in vitro fertilization cycles with or without a gonadotropin-releasing hormone agonist

OBJECTIVE

To evaluate the viability and potential for pregnancy of cryopreserved/thawed pre-embryos obtained after ovarian stimulation using gonadotropin-releasing hormone agonist (GnRH-a) adjunct therapy.

DESIGN

Retrospective clinical evaluation of all patients receiving a gonadotropin ovarian stimulation protocol (follicle-stimulating hormone/human menopausal gonadotropin [FSH/hMG]) with/without GnRH-a.

SETTING

Academic tertiary clinical care unit.

PATIENTS

Patients receiving leuprolide acetate (LA)/FSH/hMG (n = 136: LA in the luteal phase; long protocol) were compared with patients receiving FSH/hMG alone (n = 130) within the same time-frame in our program (April 1987 through October 1989).

INTERVENTIONS

All patients had both a cycle in which pre-embryos were transferred fresh and a cycle of thaw of cryopreserved pre-embryos (frozen at the pronuclear stage in a slow freeze-thaw protocol using 1,2 propanediol) transferred in monitored natural cycles.

MAIN OUTCOME MEASURES

Groups were similar in age, etiology of infertility, and cycle day 3 serum FSH levels; a significantly higher (P less than 0.001) number of preovulatory oocytes was recovered in the GnRH-a group. Both groups of patients were transferred an equal number of pre-embryos at the time of IVF. Cycles with frozen/thawed pre-embryos were evaluated based on the analysis of the three main variables that demonstrate cryopreservation efficiency: survival rate, implantation rate, and term pregnancy rate (PR).

RESULTS

Non-GnRH-a group (113 transfers): pre-embryo survival, 71.5%; PR/transfer, 24.7%; implantation rate, 16.0%; GnRH-a group (125 transfers): pre-embryo survival 71.6%; PR/transfer, 32.8%; implantation rate, 12.0% (no significant differences).

CONCLUSIONS

The use of GnRH-a produced pre-embryos of equal aptitude for development after cryopreservation at the pronuclear stage when compared with a similar gonadotropin stimulation treatment without GnRH-a.

Ovarian response in superovulated cycles after suppression with oral contraceptive steroids

The endocrine response to controlled ovarian hyperstimulation was reviewed in 94 women undergoing in vitro fertilization during 114 cycles. The purpose of this review was to evaluate the effect of short-term oral contraceptive suppression on the recovery of pituitary gonadotropin function and subsequent controlled ovarian hyperstimulation. Seventy-three cycles (64%) were adequate for oocyte retrieval. In 41 cycles (36%) hyperstimulation was discontinued. The serum 17 beta-estradiol value in women with a poor response was 57 +/- 50 pg/ml on day 8 compared with 376 +/- 334 pg/ml in the women who completed in vitro fertilization (p less than 0.05). The majority of women (84.2%) had a prompt response to controlled ovarian hyperstimulation after short-term oral contraceptive suppression. Most discontinuations were due to dominant follicle selection or luteinizing hormone surge and not to oversuppression by short-term oral contraceptives. Clinical pregnancies occurred in 15 women (20.5% of harvests).

Alterations in luteal phase progesterone and estradiol production after leuprolide acetate therapy before ovarian stimulation for in vitro fertilization

The impact of pituitary suppression with a gonadotropin-releasing hormone agonist (GnRH-a) on the luteal phase of in vitro fertilization (IVF) cycles was examined in 21 women who underwent identical stimulation regimens with and without leuprolide acetate pretreatment. The areas under the serum progesterone curves, measured over the 1st 10 days of the luteal phase, were significantly greater in the GnRH-a cycles compared with the non-GnRHa cycles, but when calculated per oocyte retrieved were similar in GnRH-a and non-GnRH-a cycles. In contrast, the areas under the luteal phase serum estradiol curves were significantly less in the GnRH-a cycles. These data suggest that GnRH-a treatment is accompanied by potentially beneficial alterations in the systemic steroidal milieu of the luteal phase of IVF cycles.

Effects of leuprolide acetate on follicular fluid hormone composition at oocyte retrieval for in vitro fertilization

The follicular fluid (FF) in 91 follicles from 17 women treated with leuprolide acetate (LA) before stimulation with gonadotropins for in vitro fertilization were analyzed for estradiol (E2), progesterone (P), androstenedione, prolactin, and human chorionic gonadotropin (hCG) and compared with the concentrations in 128 follicles from 31 women treated with gonadotropins alone. The FF E2 concentration in LA-treated patients was significantly lower than in non-LA patients for all oocyte maturational stages. Follicles containing metaphase II oocytes had significantly lower concentrations of P and hCG in LA-treated patients. These differences persisted when analysis was limited to follicles whose oocytes fertilized normally. These data indicate that in the presence of LA, normal oocyte maturation can occur despite lower intrafollicular concentrations of E2 and P.

Induction of ovulation for assisted reproduction programmes

The decision to use enhancement of the natural ovarian/menstrual cycle to attempt collection of several oocytes during IVF and GIFT cycles has dramatically increased the pregnancy rates. Furthermore, the recovery of multiple fertilizable oocytes allows for cryopreservation of extra or surplus pre-embryos (or embryos), with the consequent reduction in the risk of multiple pregnancies and the improvement of the cumulative pregnancy rate following IVF and GIFT cycles. Here, we have reviewed the underlying physiological mechanisms in the natural ovarian-menstrual cycle. Subsequently, we have analysed the more frequently utilized ovarian stimulatory regimens with special emphasis on the use of gonadotrophins. Several conclusions may be drawn from the experience to date with these methods of ovarian stimulation. Primarily, lower doses of medication, when used appropriately, may result in a more favourable outcome. Most significant, it seems to be beneficial to tailor the dosages and timing of drug administration to the patient's individual response to medication. Because ovarian stimulation therapy is difficult to manage, a major challenge in reproductive endocrinology has been to develop stimulation protocols that would 'ideally' synchronize the development of a cohort of follicles. The development of GnRH analogues (agonists and antagonists) and the experience (both in women and macaques) gained so far when these drugs are used in combination with gonadotrophins, have helped both in the understanding of the underlying physiology and in the improvement of clinical results.