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Biology of Reproduction, Vol 21, 439-445, Copyright © 1979 by Society for the Study of Reproduction
1 Cecil H. and Ida Green Center for Reproductive Biology Sciences,
Department of Obstetrics and Gynecology and Department of Physiology,
The University of Texas Health Science Center at Dallas,
Southwestern Medical School,
Dallas, Texas 75235 Secretion of luteinizing hormone (LH) and prolactin was determined in rats bearing anterior
pituitary transplants under the renal capsule and in cycling diestrous rats (controls). Control rats
were ovariectomized (OVX) during the diestrous period of the estrous cycle and the rats bearing
pituitary transplants were OVX during the diestrous period of recurring pseudopregnancies. Plasma
LH was less than 30 ng/ml in intact animals and remained unchanged for several days following
OVX in control rats. Plasma LH fluctuated for several days following OVX in 19 of 45 rats bearing
pituitary transplants under the renal capsule. The plasma concentration of prolactin was 104 ± 6
ng/ml (mean ± SEM) in rats bearing pituitary transplants and remained unchanged following OVX.
In control rats, plasma prolactin concentrations were 43 ± 4 ng/ml and fluctuated in 11 of 37 rats
following OVX. Silastic capsules of estradiol-17
implanted on Day 2 following OVX on Day 1 stimulated
surges of LH (but not of prolactin) in rats bearing anterior pituitary transplants; plasma LH reached
peak concentrations of 776 ± 102 ng/ml on Day 3 and 433 ± 48 ng/ml on Day 4. In OVX control
animals implanted with estradiol-17
, LH and prolactin surges were both observed. Peak concentrations in plasma LH were 116 ± 34 ng/ml on Day 3 and 213 ± 40 ng/ml on Day 4 and these
values were significantly below those in rats bearing pituitary transplants. Plasma progesterone
concentrations were significantly (P<0.01) higher in rats bearing pituitary transplants than in
cycling diestrous rats and decreased in all animals following OVX. It is concluded that, in rats
bearing pituitary transplants, an augmented secretion of LH can be initiated by OVX and estrogen
administration.
Note:
ACKNOWLEDGMENTS
The authors thank Sharyn Monroe, Robert Lipsey,
Sue Sherwin Martin, Linda Akers, Jodie Roberts Lyle
Larson, George Crowley and Loretta Dice for technical assistance and Ione Crandall for editorial assistance. The antiserum to rat prolactin and the reference
preparations used in the assay of prolactin and LH
were provided by the NIAMDD Rat Pituitary Hormone Program. The antiserum to LH was a gift from
Dr. G. D. Niswender. We thank Dr. L. Milewich
for the antiserum to progesterone and Dr. D. C.
Collins for the antiserum to estradiol-17
.
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