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In the long-term ovariectomized rat the secretion of LH has a pulsatile character. In such rats no difference was observed between morning and afternoon LH secretion. The administration of phenoxybenzamine, an chi-adrenergic blocker, resulted in depressed plasma LH levels. chi-Methyl-tyrosine (chi-MT), an inhibitor of tyrosine hydroxylase had no effect on(More)
Urinary estrogen excretion and plasma levels of conjugated and unconjugated 17 beta-estradiol and estriol were measured in 10 healthy, pregnant women before, during and after a 5-day course of orally administered ampicillin (2 g/day) or the same dose of amoxycillin. On the second and third day of ampicillin treatment the plasma level of conjugated estriol(More)
Preovulatory LH surges were measured in cannulated proestrous rats. Such LH peaks were also obtained by infusing pentobarbital-blocked animals with LH-RH for periods of up to 20 h; this suggested that the pituitary LH stores were exhausted. However, the total amount of LH secreted appeared more or less determined by the LH-RH dose, indicating that the size(More)
Oestrogen-induced changes in luteinizing hormone secretion, caused by continuous infusions of luteinizing hormone releasing hormone (LH-RH), appear to depend on the duration of exposure of the pituitary gland to the releasing hormone. The initial oestrogen-induced depression of the potential response of the pituitary gland to LH-RH, which always seems to(More)
If long-term ovariectomized rats are treated with the long-acting barbiturate, sodium phenobarbitone, the well-known pulsatile secretion of LH is depressed, resulting in a constant, still raised, plasma LH level. This indicates that in all probability ovariectomized rats secrete LH in both a tonic and a pulsatile way, only the latter being sensitive to(More)
The implantation of Silastic capsules containing androstenedione (release rate 63.2 +/- 4.4 micrograms/24 h) into 4-day cyclic rats resulted in a prolongation of the cycle (P less than 0.001), most rats showing 5-day cycles after the first, largely unaffected cycle. There was a reduction in ovulation rate (P less than 0.01) and lower serum LH levels on the(More)
Continuous infusions of luteinizing hormone releasing hormone (LH-RH) into phenobarbitone-treated long-term ovariectomized rats, resulted in patterns of LH secretion which were determined by the blood LH-RH concentration. Infusions of 52 ng LH-RH/h caused steadily increasing ple maintained for the rest of the experiment (9h). A similar course of plasma LH(More)
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