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.
Rodriguez
T
T
Endocrinology Service, University Hospital of San Carlos, Madrid, Spain.
Bordiu
E
E
Rubio
J A
JA
Duran
A
A
Charro
A L
AL
D000818:Animals; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017329:Triptorelin Pamoate / Q000008:administration & dosage / Q000494:pharmacology*
D017329:Triptorelin Pamoate; D011388:Prolactin; D007986:Luteinizing Hormone