TY - JOUR
T1 - Comparative stimulatory effect of gonadotrophin releasing hormone (GnRH) and GnRH agonist upon pulsatile human chorionic gonadotrophin secretion in superfused placental explants
T2 - Reversible inhibition by a GnRH antagonist
AU - Barneal, E. R.
AU - Kaplan, M.
AU - Naor, Z.
N1 - Funding Information:
This work is supported in part by a grant from Ministry of Health Chief Scientist and the Juvenile Diabetes Foundation to E.R.B.
PY - 1991/9
Y1 - 1991/9
N2 - The roles of gonadotrophin releasing hormone (GnRH) and a GnRH agonist (GnRHa) (o-Ala6-Met-Leu7-ro-N-ethylamide) in controlling pulsatile human choriomc gonadotrophin (HCG) secretion by superfused placental explants in the first trimester were examined. One minute pulses of both GnRH and GnRHa had a biphasic effect upon pulsatile HCG secretion. GnRHa was maximally effective at 10-10 M concentration, at 10-11 M the effect was mild while at 10-8 M, no effect was noted. GnRH exerted a maximal stimulatory effect at 10-8 M; at 10-10 M no effect was seen, while at 10-7 M the effect was mildly stimulatory. This was evaluated by carrying out both a between and within channel type of analysis. The effect of a GnRH antagonist GnRH(ant) upon GnRH and GnRHa-induced HCG secretion was examined. Explants were incubated overnight with 10-8 M GnRH(ant), which was also continuously administered during superfusion. The addition of 1-min pulses of GnRH and GnRHa during the exposure to GnRH(ant) failed to stimulate pulsatile HCG secretion. This effect was reversible since the response to GnRH was restored within 10 min after stopping GnRH(ant) administration. In addition, by the third cycle, co-administration of GnRH(ant) for 2 min together with 10-10 M GnRHa for 1 min completely blocked the GnRHa-induced effect. Continuous administration of 10-8 M GnRH(ant) decreased spontaneous HCG pulse amplitude and the area under the curve but failed to modify pulse frequency. In conclusion, GnRH appears to exert a receptor-dependent stimulatory effect upon pulsatile HCG secretion in superfusion in the first trimester placenta. Also, GnRH(ant) may reduce spontaneous HCG pulsatility by blocking endogenous GnRH action.
AB - The roles of gonadotrophin releasing hormone (GnRH) and a GnRH agonist (GnRHa) (o-Ala6-Met-Leu7-ro-N-ethylamide) in controlling pulsatile human choriomc gonadotrophin (HCG) secretion by superfused placental explants in the first trimester were examined. One minute pulses of both GnRH and GnRHa had a biphasic effect upon pulsatile HCG secretion. GnRHa was maximally effective at 10-10 M concentration, at 10-11 M the effect was mild while at 10-8 M, no effect was noted. GnRH exerted a maximal stimulatory effect at 10-8 M; at 10-10 M no effect was seen, while at 10-7 M the effect was mildly stimulatory. This was evaluated by carrying out both a between and within channel type of analysis. The effect of a GnRH antagonist GnRH(ant) upon GnRH and GnRHa-induced HCG secretion was examined. Explants were incubated overnight with 10-8 M GnRH(ant), which was also continuously administered during superfusion. The addition of 1-min pulses of GnRH and GnRHa during the exposure to GnRH(ant) failed to stimulate pulsatile HCG secretion. This effect was reversible since the response to GnRH was restored within 10 min after stopping GnRH(ant) administration. In addition, by the third cycle, co-administration of GnRH(ant) for 2 min together with 10-10 M GnRHa for 1 min completely blocked the GnRHa-induced effect. Continuous administration of 10-8 M GnRH(ant) decreased spontaneous HCG pulse amplitude and the area under the curve but failed to modify pulse frequency. In conclusion, GnRH appears to exert a receptor-dependent stimulatory effect upon pulsatile HCG secretion in superfusion in the first trimester placenta. Also, GnRH(ant) may reduce spontaneous HCG pulsatility by blocking endogenous GnRH action.
KW - Culture
KW - Gonadotrophin releasing hormone
KW - Human chorionic gonadotrophin
KW - Placenta
KW - Superfusion
UR - http://www.scopus.com/inward/record.url?scp=0025998952&partnerID=8YFLogxK
U2 - 10.1093/oxfordjournals.humrep.a137485
DO - 10.1093/oxfordjournals.humrep.a137485
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AN - SCOPUS:0025998952
SN - 0268-1161
VL - 6
SP - 1063
EP - 1069
JO - Human Reproduction
JF - Human Reproduction
IS - 8
ER -