scholarly journals A daily rhythm in lordosis behavior induced by a single injection of estrogen in ovariectomized rats: Effects of p-chloroamphetamine and 5-hydroxytryptophan.

1988 ◽  
Vol 34 (3) ◽  
pp. 145-148
Author(s):  
Mayumi KISHIMOTO ◽  
Hiromichi TAMADA ◽  
Junichi MORI
Keyword(s):  
Single Injection ◽  
Daily Rhythm ◽  
Ovariectomized Rats

RESTORATION BY OESTRADIOL BENZOATE OF A NEURAL AND HORMONAL RHYTHM IN THE OVARIECTOMIZED RAT

1975 ◽  
Vol 64 (1) ◽  
pp. 27-35 ◽  
Author(s):  
F. R. BURNET ◽  
P. C. B. MACKINNON
Keyword(s):  
Single Injection ◽  
Time Of Day ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Functional Link ◽  
Initial Injection ◽  
Oestradiol Benzoate ◽  
Before And After ◽  
Lh Release ◽  
The Brain

SUMMARY The rate of [35S]methionine incorporation into protein in discrete cerebral areas was measured before and after the administration of oestradiol benzoate (OB) to chronically ovariectomized rats. The circadian rhythm of incorporation which is normally seen in the intact cyclic female rat was deleted by ovariectomy. A daily rhythm of incorporation reappeared, however, in all the brain areas studied 30 h after a single injection of OB (20 μg), and was still present 12 days later. The release of luteinizing hormone (LH) after administration of 20 μg OB was measured in chronically ovariectomized animals and was found to be biphasic. High levels of LH after ovariectomy were initially reduced by negative feedback, but this phase was followed 52 h later by a facilitation of LH release between 15.00 and 18.00 h. The facilitation of LH release at this time of day was still detectable 12 days after the initial injection. The evidence for a functional link between the rhythm of neural activity which is reflected by [35S]methionine incorporation, and the ability to 'time' the facilitation of LH release is discussed.

ALTERATIONS INDUCED BY CLOMIPHENE IN THE CONCENTRATIONS OF OESTROGEN RECEPTORS IN THE UTERUS, PITUITARY GLAND AND HYPOTHALAMUS OF FEMALE RATS

1980 ◽  
Vol 87 (3) ◽  
pp. 383-392 ◽  
Author(s):  
E. Y. ADASHI ◽  
A. J. W. HSUEH ◽  
S. S. C. YEN
Keyword(s):  
Pituitary Gland ◽  
Nuclear Receptors ◽  
Single Injection ◽  
Clomiphene Citrate ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Oestrogen Receptors ◽  
Prolonged Retention

Alterations in the concentrations of oestrogen receptors in the uterus, pituitary gland and hypothalamus during the 2 weeks following a single administration of clomiphene citrate (Clomid) to immature, bilaterally ovariectomized rats were investigated. Examination of the uterine wet weight at 1, 7 and 14 days following a single injection of Clomid (100 μg, 250 μg or 10 mg) indicated significant time- and dose-related increments from a control value of 45 ± 2 (s.e.m.) mg to a maximum of 123 ± 3 mg (250 μg dose at 14 days). In contrast, a single injection of oestradiol led to a transient increase in the uterine weight on day 1 to 94 ± 6 mg, but was without effect by days 7 and 14. Analysis of the uterine DNA content 7 and 14 days after treatment with Clomid revealed significant increments from control values of 390 ± 10 μg to a high level of 558 ± 8 μg (10 mg dose at 7 days). There was a transient retention of nuclear oestrogen receptors and rapid replenishment of cytoplasmic oestrogen receptors in less than 24 h in the uteri of animals treated with oestradiol (25 μg), but determinations of receptor content in Clomid-treated animals revealed prolonged retention of nuclear receptors and delayed replenishment of cytoplasmic receptors. The duration and extent of retention of nuclear receptors and depletion of cytoplasmic receptors after treatment with Clomid were found to be dose-dependent. Fourteen days after Clomid treatment, levels of oestrogen receptors in nuclei from the uterus were still raised in all treatment groups, whereas replenishment of cytoplasmic receptors was complete in animals treated with the lower doses (100 and 250 μg) of Clomid. A single injection of Clomid (250 μg) induced similar prolonged retention of nuclear receptors and delayed depletion of cytoplasmic receptors in pituitary tissue. In contrast, changes in the content of oestrogen receptors in the hypothalamus following Clomid treatment were minimal. The limited effect of Clomid on hypothalamic tissue may mean that the pituitary gland is a more important target for this compound than is the hypothalamus. The findings have confirmed earlier reports on the long-term uterotrophic effect of Clomid and have suggested that under these long-term, in-vivo conditions, Clomid acts in the uterus and pituitary gland as a long-acting oestrogen characterized by prolonged retention of oestrogen receptors in the nucleus and delayed, but otherwise effective, replenishment of the oestrogen receptors in the cytoplasm.

A SEXUALLY DIMORPHIC RHYTHM IN OESTRADIOL-ACTIVATED LORDOSIS BEHAVIOUR IN THE RAT

1979 ◽  
Vol 83 (2) ◽  
pp. 267-274 ◽  
Author(s):  
S. HANSEN ◽  
P. SÖDERSTEN ◽  
P. ENEROTH ◽  
B. SREBRO ◽  
K. HOLE
Keyword(s):  
Daily Rhythm ◽  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Sexually Dimorphic ◽  
Female Rat ◽  
Suprachiasmatic Nuclei ◽  
Light Darkness ◽  
Lordosis Behaviour ◽  
Neonatal Castration

Ovariectomized rats exposed to constant plasma levels of oestradiol showed a daily rhythm in lordosis behaviour, with high levels of lordosis occurring during the dark portion of the daily light: darkness cycle and low levels during the light period. Similarly treated male rats failed to show a rhythm in lordosis behaviour. However, neonatal castration permitted the expression of the lordosis rhythm in male rats; conversely, an injection of 1·25 mg testosterone propionate on day 4 of life abolished the rhythm in female rats. Pinealectomy, adrenalectomy or depletion of brain 5-hydroxytryptamine levels did not affect the periodicity in lordosis behaviour but lesions in the suprachiasmatic nuclei of the hypothalamus disrupted the rhythm. It is suggested that the daily rhythm in lordosis behaviour participates in the control of the termination of heat in the female rat and that the perinatal hormone milieu may exert permanent effects on periodic functions.

Effects of various inhibitors of phenylethanolamine N-methyltransferase on pulsatile release of LH in ovariectomized rats

1986 ◽  
Vol 111 (1) ◽  
pp. 51-59 ◽  
Author(s):  
C. W. Coen ◽  
R. V. Gallo
Keyword(s):  
Preoptic Area ◽  
Single Injection ◽  
Control Level ◽  
Pulse Frequency ◽  
Ovariectomized Rats ◽  
Adrenergic Antagonist ◽  
Lh Release ◽  
The Mean ◽  
Freely Moving ◽  
Noradrenaline And Adrenaline

ABSTRACT This study was undertaken to investigate whether hypothalamic adrenaline is involved in pulsatile LH release in rats. Various inhibitors of phenylethanolamine N-methyltransferase (PNMT), the enzyme which catalyses the conversion of noradrenaline to adrenaline, were administered to freely moving ovariectomized rats bearing an atrial cannula. Blood samples were taken continuously from 09.00 to 11.00 h and from 14.30 to 17.00 h. The drugs were administered either at 11.00 h only or at both 11.00 and 14.00 h. The various treatments with the vehicle or an inhibitor of peripheral PNMT, SKF 29661, produced no decrease in any parameter of pulsatile LH release. A single injection of one of the central PNMT inhibitors, SKF 64139 or LY 134046, at 11.00 h had no effect on LH release, but when given at both times the drugs suppressed the mean LH level, pulse frequency and amplitude. The effect of these drugs on the level of dopamine, noradrenaline and adrenaline in the hypothalamus (including preoptic area) was assessed. There was no effect on the concentration of the catecholamines after SKF 29661. None of the treatments with SKF 64139 or LY 134046 resulted in a change in the level of dopamine or noradrenaline; the double dose did, however, produce a significantly greater depletion of adrenaline than that which was achieved with the single injection. These results suggest that the maintenance of normal LH pulses is dependent upon the presence of a sufficient level of hypothalamic adrenaline. The presence of at least 41% of the control level of hypothalamic adrenaline was compatible with the maintenance of LH pulses, but 30% or less of that level was insufficient for their normal occurrence. The effects of LY 134046 are particularly significant since this drug, unlike some of the other PNMT inhibitors, lacks α-adrenergic antagonist properties. J. Endocr. (1986) 111, 51–59

Effect of oestradiol-17ß on the metabolism of noradrenaline in brain slices of ovariectomized rats

1981 ◽  
Vol 98 (1) ◽  
pp. 1-7 ◽  
Author(s):  
G. Köster ◽  
H. Breuer
Keyword(s):  
Chromatographic Separation ◽  
Mandelic Acid ◽  
Competitive Inhibition ◽  
Single Injection ◽  
Brain Slices ◽  
Ovariectomized Rats ◽  
Brain Areas ◽  
Methyl Transferase ◽  
Hypothalamic Tissue ◽  
Metabolism Of Noradrenaline

Abstract. Ovariectomized rats received a single injection of 10 μg oestradiol-17β 3-benzoate; 90 min or 19 h after injection, slices of various brain areas were prepared and incubated with tritiated noradrenaline for 30 min. Methylated and non-methylated metabolites of tritiated noradrenaline were determined after chromatographic separation. Nineteen h after administration of oestradiol-17β 3-benzoate, the formation of normetanephrine, 3-methoxy 4-hydroxy phenylglycol and 3-methoxy 4-hydroxy mandelic acid was decreased (P < 0.05) in hypothalamic tissue, whereas that of 3,4-dihydroxy mandelic acid was increased (P < 0.001). In thalamus tissue a decrease of normetanephrine (P < 0.05) and an increase of 3,4-dihydroxy mandelic acid (P < 0.01) were also observed. No conclusive results were obtained with hypophyseal tissue. The present findings suggest that oestrogens reduce the methylation of noradrenaline, probably through a competitive inhibition of the catechol-O-methyl-transferase by 2-hydroxylated oestrogens.

EFFECT OF OVARIAN STEROIDS ON PREPUTIAL GLAND ODOURS IN THE FEMALE RAT

1978 ◽  
Vol 77 (3) ◽  
pp. 397-403 ◽  
Author(s):  
A. J. THODY ◽  
H. DIJKSTRA
Keyword(s):  
Single Injection ◽  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Whole Body ◽  
Female Rat ◽  
Preputial Gland ◽  
Intact Female ◽  
Oestradiol Benzoate ◽  
Experienced Male

Sexually experienced male rats were used to test for whole body and preputial gland odours of female rats. The male rats clearly preferred whole body odours of intact female rats to those of preputialectomized female rats. The male rats also preferred the odour of preputial gland tissue of intact female rats to that of ovariectomized female rats and were especially attracted to the preputial gland odours of female rats in pro-oestrus and oestrus. The preputial gland odours of ovariectomized rats that had received oestradiol benzoate for 7 days were attractive to male rats, although similar treatment with progesterone was ineffective. However, a single injection of progesterone given 72 h after a single injection of oestradiol benzoate not only made ovariectomized rats receptive, but also made their preputial gland odours attractive to male rats. The results suggest that the preputial gland of the female rat is responsible for odours that serve to attract sexually experienced male rats. Ovarian steroids, as well as controlling receptivity in the female rat, would also appear to control the production of sex attractants in the preputial gland. There was no relationship between the size of the preputial glands and their ability to attract male rats which suggests that preputial gland growth and production of sex attractants are not under the same hormonal control.

EFFECT OF RELAXIN ON OESTROGEN-INDUCED UTERINE LUMINAL FLUID ACCUMULATION IN THE OVARIECTOMIZED RAT

1974 ◽  
Vol 61 (3) ◽  
pp. 347-353 ◽  
Author(s):  
T. G. KENNEDY
Keyword(s):  
Guinea Pig ◽  
Subcutaneous Injection ◽  
Single Injection ◽  
Daily Treatment ◽  
Ovariectomized Rats ◽  
Ovariectomized Rat ◽  
Fluid Loss ◽  
Fluid Accumulation ◽  
Single Subcutaneous Injection ◽  
Fluid Formation

SUMMARY Uterine luminal fluid accumulation (ULFA) was induced in ovariectomized rats by twice daily treatment for 3 days with 0·5 μg oestradiol-17β. At the end of this treatment, rats were given a single subcutaneous injection of 0·2 ml 0·9% saline containing 0, 0·1, 1, 10, or 100 guinea-pig units (GPU) of relaxin, and ULFA was determined 15–17 h thereafter. It was reduced in animals receiving ≥ 1 GPU relaxin. This reduction in ULFA commenced 12 h after treatment of rats with 10 GPU relaxin, and was completed by 24 h. Ligation of the cervical end of the uterus prevented the loss of fluid in response to a single injection of relaxin, indicating the cervix as the route of fluid loss. Uterine luminal fluid accumulation was reduced to a greater extent by treatment of rats with 1 mg progesterone than by 10 GPU relaxin. Given concomitantly with oestrogen, relaxin had no effect on ULFA in horns which were ligated at the cervical end, indicating that relaxin did not inhibit luminal fluid formation. It is concluded from these results that the effects of progesterone on ULFA are not mediated by relaxin. The results, however, do not allow rejection of the hypothesis that the effect of prolactin on ULFA is mediated by relaxin.

INDUCTION OF SEXUAL RECEPTIVITY IN OVARIECTOMIZED RATS BY PULSE ADMINISTRATION OF OESTRADIOL-17β

1981 ◽  
Vol 89 (1) ◽  
pp. 55-62 ◽  
Author(s):  
P. SÖDERSTEN ◽  
P. ENEROTH ◽  
S. HANSEN
Keyword(s):  
Single Injection ◽  
Serum Levels ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Sexual Receptivity ◽  
Behavioural Responses ◽  
Time Points ◽  
Progesterone Treatment ◽  
Oestradiol Benzoate ◽  
Stimulation Of

Constant-release implants filled with oestradiol-17β induced sexual receptivity in ovariectomized rats in response to progesterone treatment if they were implanted 32 h before behavioural testing. A 20 h period of exposure to oestradiol, by implantation 32 h before testing and removal of the implants 20 h later, was sufficient for induction of the behaviour. The exposure time necessary for behavioural responses could be further reduced to two 4 h periods, between 32 and 28 h and between 16 and 12 h, before testing. Serum levels of oestradiol were raised within 1 h of oestradiol implantation and declined rapidly after implant removal. A single injection of oestradiol benzoate was much more potent than a single injection of oestradiol in inducing sexual receptivity in ovariectomized rats, but this difference in potency was reversed if two appropriately timed injections were given. Oestrone- or oestriol-filled implants were relatively ineffective in inducing sexual receptivity. It is suggested that oestradiol has to be present at crucial time points to prepare an ovariectomized rat to respond behaviourally to progesterone treatment and that oestradiol is the principal oestrogen in the stimulation of sexual behaviour in female rats.

A DAILY RHYTHM IN THE BEHAVIOURAL SENSITIVITY OF THE FEMALE RAT TO OESTRADIOL

1978 ◽  
Vol 77 (3) ◽  
pp. 381-388 ◽  
Author(s):  
S. HANSEN ◽  
P. SÖDERSTEN ◽  
B. SREBRO
Keyword(s):  
Daily Rhythm ◽  
Ovariectomized Rats ◽  
Sexual Receptivity ◽  
Female Rat ◽  
Suprachiasmatic Nuclei ◽  
Behavioural Effect ◽  
Filled Elastomer ◽  
Behavioural Effects ◽  
Light Darkness ◽  
Intact Rats

Ovariectomized rats were implanted with oestradiol-filled elastomer capsules which were removed at various times after implantation. Sexual receptivity was tested after implantation of a progesterone-filled elastomer capsule 42 h after the onset of treatment with oestradiol. Exposure to oestradiol for about 32 h was required for induction of receptivity. Intact rats with regular 4 day oestrous cycles, and exposed to oestradiol-filled elastomer capsules for 6 h, showed sexual receptivity 24 h after the onset of oestradiol treatment. The behavioural effects of oestradiol in both ovariectomized and intact rats depended on when during the light–darkness (LD) cycle stimulation with oestradiol occurred; maximum effects were seen only if the oestradiol capsules were implanted at 16.00 h (4 h after lights off in the 12 h L: 12 h D cycle). The behavioural effect of progesterone implants, however, did not depend on the phase of the LD cycle. The LD-dependent rhythm in oestradiol sensitivity was eliminated by lesions in the suprachiasmatic nuclei of the hypothalamus.

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