Inhibition of prolactin secretion by antiserum to the alpha- and beta-subunits of gonadotropin

Effect of pulse frequency and amplitude of D-Trp6-luteinizing hormone-releasing hormone on the pulsatile secretion of prolactin and LH

This work analyzes the effect of the pulse amplitude and frequency of a potent LHRH analog, D-Trp6-LHRH, in a perfusion system of isolated rat pituitary cells. To this purpose, we studied the LH and PRL secretion in different conditions: basal secretion, secretion after increasing concentrations of D-Trp6-LHRL (0.001, 0.01, 0.1 and 1 nM) secretion in function of the pulses frequency (2,3, and 4 pulses per h) and amplitude (0.1, 1 and 10 nM). The principal findings were: 1. The basal LH and PRL secretions was pulsatile; 2. The stimulation of LH by the analog was not dose-dependent; 3. When more than 2 pulses per h were administered, a rapid desensitization of gonadotroph to release LH (at 20-30 min) occurred; 4. There was a loss of pulsatility of PRL secretion with an increase in the pulse frequency and amplitude of the D-Trp6-LHRH, which was produced parallelly to the desensitization of the gonadotroph to release LH. In summary, these findings suggest that a rapid loss of pulsatility of the PRL when the D-Trp6-LHRH pulse frequency and amplitude is increased might be due to the early desensitization of the gonadotroph to the analog.

Leuprolide acetate elevates prolactin during ovarian stimulation with gonadotropins

OBJECTIVE

The purpose of this study was to determine whether gonadotropin-releasing hormone agonist further increases the prolactin rise accompanying ovarian stimulation.

DESIGN

Serum prolactin concentrations were compared between cycles with and cycles without the use of leuprolide acetate (LA) matched for estradiol levels. Relationships of prolactin levels to cycle outcomes were examined.

SETTING

The study took place at a private fertility center.

PATIENTS

Patients were women receiving stimulation for oocyte retrieval using human menopausal gonadotropins.

INTERVENTIONS

No interventions were used.

MAIN OUTCOME MEASURES

Serum prolactin level, fertilization rate, embryo quality, and pregnancy were the main outcome measures.

RESULTS

Higher serum prolactin was associated with both higher estradiol levels and use of LA but did not have any effects on fertilization rate, embryo quality, or occurrence of pregnancy.

CONCLUSION

LA stimulates prolactin release during ovarian stimulation but without apparent consequence.

Prolactin secretion in idiopathic hypogonadotropic hypogonadism during pulsatile luteinizing hormone-releasing hormone long-term administration

Recent data seem to suggest that LHRH may be involved in the modulation of PRL secretion. We studied the PRL pattern in 9 males (age range 18-38 yr) with idiopathic hypogonadotropic hypogonadism (IHH) before and during long-term pulsatile LHRH therapy (120-160 ng/kg bw every 120 min sc) in order to evaluate variations in the spontaneous PRL secretion or LHRH-induced presence of PRL pulse. LH, FSH and PRL secretion was evaluated every 15 min for 3 h on day 0, day 30 and days 90-150. Before and during LHRH therapy PRL 24-h integrated concentration (IC) and gonadotropin or PRL response to LHRH test (50 micrograms iv/bolus) were evaluated. On day 0 spontaneous PRL pulses were found in 2 IHH patients. On day 30 PRL pulses were found in 4 cases. On days 30-90 PRL pulses were sporadically concomitant with LHRH-induced LH pulses. Mean PRL levels and 24-h IC of PRL were found to be significantly (p less than 0.05) increased during pulsatile LHRH administration. A significant positive (p less than 0.01) correlation was observed between testosterone and PRL levels during LHRH therapy. When compared to a significant LH response to LHRH iv bolus, no modification of PRL secretion was found. The present study did not show any relationship between LHRH administration and PRL secretion. It might be hypothesized that LHRH does not play a determinant role in PRL secretion and does not seem to modulate PRL secretory pattern in IHH males.

Prolactin and its response to the luteinizing hormone-releasing hormone thyrotropin-releasing hormone test in patients with endometriosis before, during, and after treatment with danazol

Basal levels of prolactin (PRL) were studied in 16 normal women and in 60 women with endometriosis, 37 of whom were infertile. In addition, the authors studied the response to an intravenous (IV) injection of luteinizing hormone-releasing hormone (LH-RH) (100 micrograms) plus thyrotropin-releasing hormone (TRH) (300 micrograms) in the 16 normal women and in 18 endometriosis patients, examining the basal PRL and thyrotropin, and at 15, 30, 45, 60, and 120 minutes after the IV bolus. After laparoscopy and/or conservative surgery, the patients were treated with danazol for 6 months and a second laparoscopy was performed. The LH-RH/TRH test was carried out in the third month of danazol treatment in 6 endometriosis patients and before the second laparoscopy in 11 patients. The results show that there was both an increase in the mean basal levels of PRL and in the percentage of cases of moderate hyperprolactinemia in endometriosis patients. There also was a greater rise in PRL with the LH-RH/TRH test in moderate and severe endometriosis. The PRL response was significantly greater in endometriosis than in normal women, and was not related to TSH response. Danazol treatment reduced significantly the PRL response. The PRL response before treatment was significantly higher in patients who after treatment showed persistent endometriosis at the second laparoscopy. This could suggest a lower effectiveness of danazol in patients with endometriosis and a PRL hyper-response to LH-RH/TRH.