RESPONSE OF THE ADULT FEMALE RATS TO OVARIECTOMY AS DETERMINED BY LUTEINISING HORMONE RADIOIMMUNOASSAY
AbstractThis study was carried out to see the response of ovariectomy in adult female rats asdetermined by rat Luteinising Hormone (rLH) Radioimmunoassay (R1A). Animals weredivided in two groups. Group I (control, n=6) were sham ovariectomised and group II(experimented, n=4) were ovariectomised. Next day at 1400 hours’ rats were sacrificed andtheir plasma was collected for rLH, RIA. It was observed that there was highly significantincrease in plasma rLH (P<0.001) in experimental group as compared to controls. Also theincrease in the weights of hypothalamus and anterior pituitary of experimental group washighly significant (P<0.001) as compared to controls. This shows that this rise in plasmarLH and weights of hypothalamus and anterior pituitary was due to loss of negative feedbackeffect of ovarian steroids.
Carmel PVV. Araki S, Ferin M. Pituitary stalk portal
blood collection in Rhesus monkeys: Evidence for
pulsatile release of gonadotropin-releasing hormone
(GnRH). Endocrinology 1976: 99:243-47.
Karsch F.I, Legan S.J, Hauger RL. Foster DL Negative
feedback action of progesterone on tonic luteinizing
hormone secretion in the ewe: Dependence on the
ovaries. Endocrinology 1977; 101:800-806.
Kasa-Vuu JZ, Dahl GE, Evans NP. Thrun LA. Moenter
SM, Padmanabhan V, Karsch F.I. Progesterone blocks
the estradiol-induced gonadotropin discharge in the
ewe by inhibiting the surge of gonadotropin-releasing
hormone. Endocrinology 1992; 131:208-12.
De Leo V. Lanzetta D. Vanni AL, D'Antona D, Severi
FM Low estrogen oral contraceptives and the
hypothalamus pituitary axis. Contraception 1991:44:
Xia L. Vugt DV, Alston F.J, Luchaus J, Ferin M. A
surge of gonadotropin-releasing hormone accompanies
the estradiol- induced gonadotropin surge in the rhesus
monkey. Endocrinology 1992; 131: 2812-20.
Gallo RV. Neuroendocrine regulation of pulsatile
luteinizing hormone release in the rat.
Neuroendocrinology 1980; 30:122-31.
Bergman MD, Schachter BS, Karelus K, Combatsiaris
EP. Garcia T, Nelson JF. Up-regulation of the uterine
estrogen receptor and its messenger ribonucleic acid
during the mouse estrous cycle. The role of estradiol.
Endocrinology 1992, 130: 1923-30.
Khan UA, Khan SJ, Aslant M. Effect of
Difluromethylornithine (DFMO) on Ovulation of Rats.
Pak Armed Forces Med. .1. 1995, 45(2): 26-29.
Monroe SE. Parlow AF, Midgley AR Jr
Radioimmunoassay for rat luteinizing hormone.
Endocrinology 1968: 83: 1004-12.
Nicholson S, Aslant M, Gillham B, Jones M Prolonged
sensation of pituitary- glands in vitro to repeated
administration of luteinising hormone-releasing
hormone: Effects of pulse frequency, ovariectomy,
estradiol and progesterone. Neuroendocrinology 1987;
Goldman JM, Cooper RL, Edwards TL, Rehnberg GL,
McElroy WK, Hein JF. Suppression of the luteinizing
hormone surge by chloradimeform in ovariectomized,
steroid-primed female rats. Pharmacol Toxicol 1991:
Clarke IJ. Variable patterns of gonadotropin-releasing
hormone secretion during the estrogen-induced
luteinizing hormone surge in ovariectomized ewes.
Endocrinology 1993; 133: 1624-32.
Andrews WW, Mizejewski GJ, Ojeda SR.
Development of estradiol-positive feedback on
luteinizing hormone release in the female rat: A
quantitative study. Endocrinology 1981; 109: 1404-13.
Nicholson SA, Aslam M, Chuang TT, Gillham B. Jones
MT. Effect of difluoromethylornithine on the LH surge
and subsequent ovulation in the rat. J. Endocrinoly
, 117: 447-53.
Sarkar DK. Fink G. Luteinizing hormone releasing
factor in pituitary stalk plasma from long-term
ovariectomized rats: Effects of steroids. J Endocr 1980;
Sanchez-Criado JE. Galiot F. Bellido C. Gonzalez D,
Tebar M. Hypothalamus-pituitary-ovarian axis in
cyclic rats lacking progesterone actions. Biol. Reprod