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S Plas-Roser

Publications and source records attributed to S Plas-Roser.

29 records · Page 2Linked to original sources
PubMed1977

New data concerning the control by the adrenals of sexual receptivity in the rat.

The proportion of receptive females during the night from proestrus to estrus (mating frequency) was estimated in 4-day cyclic rats ovariectomized at different times of the day of proestrus. A sharp decrease in mating frequency occurred in females ovariectomized at 15:00-16:00 as compared with intact animals. A slighter, although significant decrease in mating frequency, was observed in females ovariectomized at 8:00-9:00 and 13:00-14:00. Sexual receptivity was only partially recovered following ovariectomy at 17:30-18:30. Chronic adrenalectomy completely prevented estrous receptivity in females ovariectomized at any time of proestrus as compared to adrenalectomized nonovariectomized females which displayed a normal estrous receptivity during the night from proestrus to estrus. A higher blood progesterone level was observed in receptive rats between 15:00 and 16:00 than in nonreceptive ones. The temporal relationships between the ovary and the adrenals in the control of estrous receptivity were discussed in the light of these observations.

Adrenal Glands↗
PubMed1977

The role of follicle-stimulating hormone (FSH), in combination with luteinizing hormone (LH), in oestrogen-induced ovulation during the oestrous cycle in the rat.

Studies were undertaken to determine the role played by FSH in oestrogen-induced ovulation in 4-day cyclic female rats. About one half of the experimental animals receiving 10 microng oestradiol benzoate (OeB) subcutaneously, on the morning of dioestrus I, displayed luteinization or/and ovulation, when sacrificed on the morning of expected pro-oestrus. Pento-barbitone administered on dioestrus II at 18.00 did not prevent this action of OeB. A simultaneous LH and FSH surge was observed in the serum of half of the OeB-treated females killed by decapitation of dioestrus II at 17.30. The LH surge was decreased in OeB-treated females bled by cardiac puncture under pentobarbitone anaesthesia at dioestrus II at 17.30. This bleeding procedure almost completely suppressed the luteinizing effects of OeB. It was concluded that i) OeB caused a synergistic release of LH and FSH ii) bleeding by cardiac puncture as such may constitute a source of inhibition of OeB-induced luteinization.

Animals↗
PubMed1977

[New data on luteotropic mechanism of action of estrogens during the rat estrus cycle].

An increase in peripheral blood progesterone concentration was observed in diestrus II, at 17:30 in 4-day cyclic female rats subcutaneously injected with 10 microgram estradiol benzoate (EB) at 10:00-11:00 on diestrus I. Pentobarbital injection (30 mg/kg) at 13:30 on diestrus II did not prevent this effect on EB. By contrast PB injected at 13:30 on diestrus II as above completely suppressed the luteinizing or ovulating effects of EB. The action of estrogen on blood progesterone level was therefore concluded to be unrelated to the mechanisms underlying estrogen-induced ovulation luteinization in the cyclic female rat.

Animals↗
PubMed1976

[Proestral modification of plasma LH and FSH levels in rats exposed to FSH at the beginning of a 4-day cycle].

Four day cyclic female Rats were injected with dosages of FSH capable of causing superovulation and or superluteinization at the end of the cycle. A decrease in plasma LH and FSH was observed during the "critical period" on the afternoon of proestrus. The exogenous FSH was then supposed to increase the number of follicles sensitive to the ovulating and luteinizing action of LH.

Animals↗
PubMed1976

Hormonal mechanisms involved in the control of oestrous cycle duration by the odour of urine in the rat.

The mechanisms involved in the reduced cycle duration following exposure to the odour of urine were studied in natural and experimental 5-day cyclic female Wistar rats. A decrease in the rate of ovarian progesterone secretion from the morning of dioestrus I to that of dioestrus II was observed in females whose cycle duration was reduced from 5 to 4 days following exposure to the odour of rat urine. No decrease in ovarian progesterone secretion occurred in females maintaining a 5-day cyclicity despite exposure to this odour. An increase in follicular growth was noted in females with cycle duration reduced from 5 to 4 days, when compared with those maintaining a 5-day rhythm. As a result of exposure to the odour of urine no reduced cycle duration occurred in females with cycles lengthened from 4 to 5 days as a result of progesterone injection on dioestrus I of 4-day cycles. Hence the decrease in ovarian progesterone secretion, induced by exposure to the odour of urine, is considered to cause a speeding up in follicular growth, thereby reducing oestrous cycle duration in 5-day cyclic rats.

Animals↗
PubMed1976

[Mechanisms operating in the action of pheromones on the estrous cycle of the guinea-pig].

An increase in follicular growth was observed on the 6th and 8th days of the period of vaginal closure (PVC) in adult cyclic female guinea-pigs exposed to the odor of male urine from the beginning of this period. No statistically significant decrease in peripheral blood progesterone level occured on the same days of the PVC following exposure to the odor of male urine.

Animals↗
PubMed1975

[Effect of exogenous progesterone on 17 beta estradiol secretion in 4-day cyclic rats].

The rate of ovarian 17 beta oestradiol was showed to be decreased on the decreased on the afternoon of dioestrus 2 in 4-day cyclic female rats with cycles prolonged to 5 days following progesterone treatment as compared to untreated 4-day cyclic females. OEstradiol values also appeared lower on dioestrus 3 and prooestrus in experimental 5-day cycles than, on prooestrus, in natural 4-day cycles.

Animals↗