Gonadotropin releasing hormone agonists have a stimulatory effect on pituitary gland after down regulation

The aim of this prospective study was to investigate the effect of daily administration GnRH agonist on the pituitary gland after a period of down regulation and the relationship between any remaining agonistic response and the outcome of IVF. Several blood samples were obtained from 70 patients underwent IVF/ICSI after long pituitary down regulation before and 60 minutes after GnRH agonist administration on three occasions: S1: Day 2 of the stimulating cycle after down regulation and before starting gonadotrophin stimulation. S2: Day 5 [day 3 of gonadotrophin stimulation]. S3: Day .9 [day 7 of gonadotrophin stimulation]. Samples were analysed for FSH, LH, and E2. Each subject acted as her own control. There was a significant rise [P<0.001] in LH concentrations [pulse] after each buserelin injection on the three occasions. The FSH response was also significant on SI [P<0.001] and S2 [P<0.007]but not S3, the response of FSH was masked by the exogenous administration of gonadotrophin. E2 response did not show any significant difference in concentration after any buserelin injection. The GnRH agonist stimulates the pituitaly gland by producing pulses of LII and FSH even after down regulation. The resulting pulses of LH following the GnRH administration are probably the source of endogenous LH required for optimal ovarian response. The combined rise of LI-I and FSH may explain the formation of ovarian Cysts with GnRH agonist administration alone

Pituitary gland activity following ultralong versus long down regulation

The aim of this prospective comparative study was to investigate the pituitary gland activity after prolonged down regulation with Goserelin and after milder down regulation of patients underwent IVF treatment under long down regulation protocol with daily injections of Buscrelin. The pituitary activity of 21 patients received Goserelin [Zoladex] for 3 months was investigated and the results were compared with the pituitary activity of 50 patients received daily Buserelin from day 21 of the cycle preceding the IVF treatment cycle [8-14 days]. The pituitary gland achieved a profound degree of down regulation 4 weeks post Goserelin injections and maintained the same degree of down regulation following each subsequent injection. The LH and E2 were more profoundly suppressed by the depot GnRH agonist [Zoladex] than the daily Buserelin administration. However the pituitary remains responsive to Buserelin by producing pulses of FSH and LH despite the down regulation in both groups. The amplitude of these pulses were similar although the LH levels were significantly higher in group 2. These pulses are probably the source of endogenous LH required for steroidogenesis. This explains the success of IVF after profound down regulation despite the use of Pure FSH for ovarian stimulation

Ovarian reserve after prolonged down regulation of pituitary gland

The aim of this prospective study was to investigate the ovarian reserve and pituitary gland activity after prolonged down regulation with Goserelin for 2 months. Thirty patients with stage II-IV endometriosis received Goserelin [Zoladex] every 4 weeks]. The ovarian reserve was checked by measuring the anti-mullerian hormone [AMH] level every 4 weeks at the same time of checking the resting FSH, LH, and E2. The pituitary response to the Buserelin was assessed by measuring the FSH, LH and E2 one hour post 500ug Buserelin injection and before the scheduled Zoladex injection every 4 weeks. The ovarian reserve was not affected by prolonged down regulation with Goserelin. The pituitary gland achieved a profound degree of down regulation 4 weeks post Goserelin and maintained the same degree of down regulation following each subsequent injection. However the pituitary gland retains some degree of activity by responding to Buserelin and producing pulses of FSH and LH despite the profound down regulation

residual pituitary activity after down regulation

To investigate the pituitary gland activity over a period of three hours after adequate down regulation. This prospective study started with twelve patients underwent IVF treatment under long down regulation protocol. When they attended on day 2 of the treatment cycle to confirm down regulation, a blood sample was obtained from each patient before the daily buserelin administration and repeated at 30 minutes, 1 hour, 2 hours and 3 hours post the buserelin administration to check the changes in FSH, LH and E2 levels. There were obvious and significant increases in LH [P < 0.001] and FSH [P = 0.04] concentrations post buserelin administration that reached to a maximum levels one hour post buserelin and lasted for at least 3 hours. after a clinically successful down-regulation the pituitary gland remains responsive to the GnRH agonist and tonically releases LH in response to the GnRH agonist administration which may have clinical implications