Effect of Progesterone on Induced Ovulation in Immature Rats

Ying, Shao‐Yao; Meyer, Roland K.

doi:10.1530/jrf.0.0200279

Cited by 13 publications

(5 citation statements)

References 15 publications

(23 reference statements)

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“…In addition, progesterone has been shown to increase plasma LH (Nallor, Antunes-Rodrigues & McCann, 1966;Caligaris et al 1968) and to increase pituitary LH (Labhsetwar, 1969). Similar observations on stimulation (McCormack & Meyer, 1963;Zarrow & Hurlbut, 1967;Ying & Meyer, 1969) and inhibition (Zarrow & Hurlbut, 1967;Ying & Meyer, 1969) of ovulation by progesterone have been reported in the PMS-treated immature rat. Thus the findings indicate that the action of progesterone on ovulation is biphasic in the immature rat as well as in the mature rat.…”

Section: Treatment With Pregnant Mare Serumsupporting

confidence: 74%

Regulation of Pituitary Ovulating Hormone Concentration in the Immature Rat Treated With Pregnant Mare Serum

Zarrow¹,

Dinius²

1971

Journal of Endocrinology

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The concentration of luteinizing hormone (LH) in the pituitary gland of the 28-day-old female rat increased from a value of 8\m=.\0 \g=m\equiv./mg fresh anterior pituitary at zero time to 20\m=.\1 \g=m\g at 51 h after treatment with 30 i.u. pregnant mare serum (PMS). The level then fell to 8\m=.\1 \g=m\g at 56 h. PMS had no effect on pituitary LH levels in the ovariectomized rat. Three daily injections of 5\m=.\0 \ g=m\ g of oestradiol benzoate caused an increase in pituitary LH levels to 16\m=.\1 \ g=m\ g at 51 h after the onset of the oestrogen treatment. This value is not significantly different from the level (20\m=.\1\g=m\g/mg fresh weight) found in the intact, PMS-treated, immature rat. Uterine weights were also comparable for the two groups. Treatment with lower doses of oestradiol benzoate had no effect on pituitary LH levels and also failed to increase the uterine weight to values comparable with those obtained after PMS treatment. Treatment of 28-day-old, intact, female rats with 2 mg of progesterone at 24 h after the PMS injection resulted in a significant drop in pituitary LH levels.

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Section: Treatment With Pregnant Mare Serumsupporting

confidence: 74%

Regulation of Pituitary Ovulating Hormone Concentration in the Immature Rat Treated With Pregnant Mare Serum

Zarrow¹,

Dinius²

1971

Journal of Endocrinology

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“…Proges¬ terone administration can advance ovulation by 24 h in PMSG-treated rats (Ying & Meyer, 1969;Zarrow & Gallo, 1969). The serum progesterone response to PMSG was reduced in our study by prior cortisolacetate treatment and this may explain why fewer of these animals than controls had ovulated within 48 h of PMSG injection.…”

Section: Discussionmentioning

confidence: 46%

Neonatal glucocorticoid administration: effect on the diurnal rhythm of serum concentrations of corticosterone, progesterone and LH, and the response to pregnant mare serum gonadotrophin in immature female rats

Mann¹,

Ir²,

Cost³

1984

Journal of Endocrinology

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The effects of neonatal cortisol acetate administration on diurnal changes in serum corticosterone, progesterone and LH and on the response to pregnant mare serum gonadotrophin (PMSG) were examined in immature female rats. Neonatal cortisol treatment (250 micrograms/rat) abolished the diurnal rhythm of serum progesterone in rats at 27-29 days of age, and lowered overall the serum progesterone response to PMSG. Neonatal cortisol also reduced the number of animals ovulating on day 28 after PMSG injection 48 h earlier. This dosage of cortisol did not alter the diurnal rhythm of serum corticosterone in these animals. Serum LH concentrations in control rats at 27-29 days of age did not differ between 09.00 and 18.00 h, and prior treatment with cortisol acetate did not significantly influence serum concentrations of this hormone. Our data suggest that ovarian production of progesterone contributes significantly to diurnal fluctuations of this steroid in the circulation of immature rats. Perinatal exposure to cortisol acetate abolishes the diurnal rhythm of serum progesterone and impairs the ovarian response of the immature female rat to PMSG. The mechanism(s) by which cortisol acetate alters these processes remains to be determined.

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“…In hamsters, however, Greenwald (1971) showed that simultan¬ eous injection of progesterone with lower doses of PB (which did not cause behavioural depression) restored ovulation in many of the treated animals. The effects produced by PB and progesterone are therefore to be interpreted with caution as the time and dose of injection in relation to the stage of the oestrous cycle and lighting regimen, and the presence of other steroids can all influence the results (Strauss, 1964;Ying & Meyer, 1969b;Harris & Naftolin, 1970). Although the present study deals with the effects of progestational steroids, the profound influence of oestrogen in the sequence of events leading to ovulation is known to be equally important (Neill, Freeman & Tillson, 1971).…”

Section: Discussionmentioning

confidence: 99%

Induction of Ovulation by Pregn-5-Ene-3,20-Dione and Progesterone in Immature Rats Treated With PMSG and Phenobarbital

Sridharan¹,

Meyer²,

Karavolas³

1974

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Progesterone and pregn-5-ene-3,20-dione, the proposed intermediate between pregnenolone and progesterone in the rat ovary, were able to overcome the phenobarbital (PB)-induced block of ovulation in the PMSG-primed immature rats when given 3\ m=1/ 2\ hr after PB. Pregnenolone failed to cause ovulation in any of the animals treated with phenobarbital, providing support for the hypothesis that the ovulation-inhibiting action of PB may be due in part to its inhibitory action on the step in steroidogenesis between pregnenolone and progesterone. The principal metabolites of progesterone in the hypothalamus and uterus, 5\g=a\-pregnane-3,20-dione and 3\g=a\-hydroxy-5\g=a\-pregnan-20-one, were not able to overcome the PB-induced block of ovulation. These results suggest that the action of progesterone in overcoming the PBinduced block of ovulation is not because of its transformation to these two compounds.

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Effect of Progesterone on Induced Ovulation in Immature Rats

Abstract: Summary. Female rats treated with 3 i.u. PMSG

Cited by 13 publications

References 15 publications

Regulation of Pituitary Ovulating Hormone Concentration in the Immature Rat Treated With Pregnant Mare Serum

Regulation of Pituitary Ovulating Hormone Concentration in the Immature Rat Treated With Pregnant Mare Serum

Neonatal glucocorticoid administration: effect on the diurnal rhythm of serum concentrations of corticosterone, progesterone and LH, and the response to pregnant mare serum gonadotrophin in immature female rats

Induction of Ovulation by Pregn-5-Ene-3,20-Dione and Progesterone in Immature Rats Treated With PMSG and Phenobarbital

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