beta-Endorphin plasma levels after intravenous administration of GnRH in female rats.
OBJECTIVE
The study investigates the effects of intravenously administered GnRH on plasma beta-endorphin levels in female proestrous rats.


METHODS
Sixteen adult female proestrous Wistar rats, 220-250 g, were implanted with two indwelling catheters, one intracarotid and one intrajugular. Ten ng GnRH/100 microl distilled water or 100 microl saline (control) were infused in eight animals per group every 20 min from 12:30 to 14:30 h. Blood was withdrawn through the intracarotid catheter just before the initial infusion (12:30 h) and at 14:00, 15:30, 16:30 and 17:30 h for the determination of plasma beta-endorphin levels. The Mann-Whitney test was used for comparison between GnRH-treated and control rats and the Wilcoxon test within each treatment group.


RESULTS
beta-Endorphin levels of GnRH-treated rats were not significantly different at any sampling moment neither compared to preinfusion time nor to the corresponding controls.


CONCLUSIONS
Intravenously administered GnRH was not sufficient for any possible effect on the secretion of beta-endorphin from rat pituitary and further investigation is needed to demonstrate if a different experimental model would have any significant effect.
Matziari
C
C
Department of Physiology, Faculty of Medicine, Aristotle University of Thessaloniki, Greece. matziari@phed.auth.gr
Ioannidou
M
M
Kaiki-Astara
A
A
Guiba-Tziampiri
O
O
D000818:Animals; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007262:Infusions, Intravenous; D007986:Luteinizing Hormone / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D001615:beta-Endorphin / Q000097:blood*
D007987:Gonadotropin-Releasing Hormone; D001615:beta-Endorphin; D007986:Luteinizing Hormone