EXPERIMENTAL STUDIES ON THE REGULATION OF CORPUS LUTEUM FUNCTION IN CASTRATED MALE RATS BEARING A TRANSPLANTED OVARY

1963 ◽  
Vol 43 (2) ◽  
pp. 246-254 ◽  
Author(s):  
G. H. Zeilmaker
Keyword(s):  
Pituitary Gland ◽  
Corpus Luteum ◽  
Functional Activity ◽  
Experimental Studies ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Corpora Lutea ◽  
Female Rat ◽  
Progesterone Production

ABSTRACT The functional activity of artificially induced corpora lutea in isologous ovaries transplanted into castrated male rats has been studied. Criteria for progesterone production were the morphology of vaginal transplants and the distribution of sudanophilic material in the corpus luteum cells. It was found that spontaneous functional activity of the corpora lutea did not occur in short-term experiments. Progesterone production was observed, however, in animals also bearing an isotransplanted (either male or female) pituitary gland, and in animals which received daily injections of reserpine. It is suggested that the normal influence of the central nervous system on the secretion of luteotrophic hormone is inhibitory in male as well as in female animals. Some aspects of the induction and maintenance of luteal function in castrated male rats bearing a transplanted ovary have been studied and compared with similar phenomena in the female rat. A real pseudopregnancy, i. e. maintained by the pituitary in situ during a defined period, as can be observed in female rats, could not be induced in these animals. In animals also bearing an isografted pituitary gland, luteolysis was not observed in experiments lasting up to 45 days. It is suggested that these findings may be correlated with the way in which the luteinizing hormone is secreted in the male rat.

Observations on the effects of prolactin on LH-receptors and steroidogenesis in corpus luteum and testis of the hypophysectomized rat

1982 ◽  
Vol 99 (3) ◽  
pp. 437-442 ◽  
Author(s):  
R. J. C. van Straalen ◽  
G. H. Zeilmaker
Keyword(s):  
Pituitary Gland ◽  
Corpus Luteum ◽  
Binding Sites ◽  
Female Rats ◽  
Male Rats ◽  
Rapid Decline ◽  
Corpora Lutea ◽  
Serum Progesterone ◽  
Male And Female Rats ◽  
Hypophysectomized Rats

Abstract. In this study the effects of hypophysectomy and autotransplantation of the pituitary gland on the concentration of hCG-binding sites (LH-receptors) and steroidogenesis in the corpus luteum and the testis of the rat were investigated. It was found that during pseudopregnancy both hCG-binding to homogenates of isolated corpora lutea and the progesterone levels in blood increase until day 7 and subsequently decrease until day 13. Hypophysectomy on day 5 led to a decrease of the number of LH-receptors and the serum progesterone level. By contrast hypophysectomy followed by autotransplantation of the pituitary gland increased the LH-receptor concentration and progesterone synthesis in spite of non-detectable LH-levels. Progesterone implants in hypophysectomized rats did not influence the number of LH-receptors. Hypophysectomy on day 0 without pituitary gland transplantation did not prevent the formation of some luteal LH-receptors measured on day 5 although progesterone was not secreted. A similar effect of prolactin secreted by pituitary autografts on LH-receptors was seen in the testis. The rapid decline of the number of binding sites normally observed after hypophysectomy was prevented by the presence of two pituitary autografts. Testosterone and LH-levels were non-detectable in the operated male rats. These data show that progesterone secretion by the corpora lutea is always associated with the presence of LH-receptors, regardless whether serum LH-levels are detectable or not. Moreover it appears that prolactin maintains or even increases the amount of LH-receptors in hypophysectomized male and female rats.

ASPECTS OF THE REGULATION OF CORPUS LUTEUM FUNCTION IN ANDROGEN-STERILIZED FEMALE RATS

1964 ◽  
Vol 46 (4) ◽  
pp. 571-579 ◽  
Author(s):  
G. H. Zeilmaker
Keyword(s):  
Pituitary Gland ◽  
Corpus Luteum ◽  
Luteal Phase ◽  
Female Rats ◽  
Male Rats ◽  
Corpora Lutea ◽  
Normal Female ◽  
Cervical Stimulation ◽  
Lh Secretion

ABSTRACT Some aspects of the regulation of function of artificially induced corpora lutea in androgen-sterilized female rats have been studied. The morphology of the vaginal epithelium and the distribution of sudanophilic materials in the luteal cells served as criteria for possible corpus luteum function. Pseudopregnancy, i. e. corpus luteum function during a defined period, as can be observed in female rats after sterile copulation, could not be induced in androgen-sterilized rats by daily cervical stimulation, by three daily injections of reserpine or by the presence of an isotransplanted pituitary gland during the first four days after the induction of corpus luteum formation. Prolonged corpus luteum function during at least 45 days was observed in animals bearing an isotransplanted pituitary gland under the kidney capsule. It is suggested that the evenly distributed sudanophilia in these corpora lutea is a result of the »tonic LH secretion« of the pituitary gland in situ. Comparison with similar studies in male rats led to the conclusion that an ovulation-inducing release of gonadotrophins plays a major role in the termination of the luteal phase in normal female rats. In ovariectomized androgen-sterilized rats treated with progesterone and oestrone a decreased response of the uterus to a traumatic stimulus was noticed as compared with the response in similarly treated normal rats.

scholarly journals Increased bioactivation of dihaloalkanes in rat liver due to induction of class Theta glutathione S-transferase T1-1

1998 ◽  
Vol 335 (3) ◽  
pp. 619-630 ◽  
Author(s):  
Philip J. SHERRATT ◽  
Margaret M. MANSON ◽  
Anne M. THOMSON ◽  
Erna A. M. HISSINK ◽  
Gordon E. NEAL ◽  
...  
Keyword(s):  
Western Blotting ◽  
Rat Liver ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Female Rat ◽  
Glutathione S Transferase ◽  
Chemopreventive Agents ◽  
Cytoplasmic Staining ◽  
Potent Inducer

A characteristic feature of the class Theta glutathione S-transferase (GST) T1-1 is its ability to activate dichloromethane and dibromoethane by catalysing the formation of mutagenic conjugates. The level of the GSTT1 subunit within tissues is an important determinant of susceptibility to the carcinogenic effects of these dihaloalkanes. In the present study it is demonstrated that hepatic GST activity towards these compounds can be elevated significantly in female and male Fischer-344 rats by feeding these animals on diets supplemented with cancer chemopreventive agents. Immunoblotting experiments showed that increased activity towards the dihaloalkanes is associated with elevated levels of the GSTT1 subunit in rat liver. Sex-specific effects were observed in the induction of GSTT1 protein. Amongst the chemopreventive agents tested, indole-3-carbinol proved to be the most potent inducer of hepatic GSTT1 in male rats (6.2-fold), whereas coumarin was the most potent inducer of this subunit in the livers of female rats (3.5-fold). Phenobarbital showed significant induction of GSTT1 only in male rat liver and had little effect in female rat liver. Western blotting showed that class Alpha, Mu and Pi GST subunits are not co-ordinately induced with GSTT1, indicating that the expression of GSTT1 is determined, at least in part, by mechanisms distinct from those that regulate levels of other transferases. The increase in amount of hepatic GSTT1 protein was also reflected by an increase in the steady-state level of mRNA in response to treatment with chemopreventive agents and model inducers. Immunohistochemical detection of GSTT1 in rat liver supported the Western blotting data, but showed, in addition to cytoplasmic staining, significant nuclear localization of the enzyme in hepatocytes from some treated animals, including those fed on an oltipraz-containing diet. Significantly, the hepatic level of cytochrome P-450 2E1, an enzyme which offers a detoxification pathway for dihaloalkanes, was unchanged by the various inducing agents studied. It is concluded that the induction of GSTT1 by dietary components and its localization within cells are important factors that should be considered when assessing the risk dihaloalkanes pose to human health.

Effects of acute administration of 2-hydroxylated metabolites of oestrogens on LH and prolactin secretion in male and female prepubertal rats

1984 ◽  
Vol 103 (3) ◽  
pp. 317-325
Author(s):  
A. K. Brar ◽  
G. Fink
Keyword(s):  
Plasma Concentration ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Female Rat ◽  
Uterine Weight ◽  
Immature Female ◽  
Male And Female ◽  
Immature Male ◽  
Lh Release

ABSTRACT The effects of catechol oestradiol and catechol oestrone on the release of LH and prolactin were investigated in immature male and female Wistar rats. In male rats both catechol oestradiol and catechol oestrone significantly increased the plasma concentration of LH, and catechol oestradiol but not catechol oestrone significantly increased the plasma concentration of prolactin and decreased the pituitary concentration of LH. The parent oestrogens, oestradiol-17β and oestrone, had no effect on plasma LH concentrations, but both increased significantly the plasma concentration of prolactin, and oestrone but not oestradiol-17β increased the pituitary concentration of LH. In immature female rats, catechol oestradiol inhibited the surge of LH and the increase in uterine weight induced by injecting pregnant mare serum gonadotrophin (PMSG). The injection of oestrone induced an increase in the plasma concentration of LH which was about nine times greater than that produced by oestradiol-17β. There were no significant differences in the effects of these steroids on plasma prolactin concentration. These results (i) confirm that in the immature male rat catechol oestrogens can stimulate LH release and show that catechol oestradiol can increase prolactin release, (ii) show that catechol oestradiol can inhibit the stimulatory effects of PMSG on LH release and uterine weight in the immature female rat, and (iii) demonstrate that oestrone can stimulate LH release in the immature female rat. J. Endocr. (1984) 103, 317-325

EXPERIMENTAL EVALUATION OF DIURETICS IN THE RAT

1956 ◽  
Vol 34 (1) ◽  
pp. 903-911
Author(s):  
J. D. McColl ◽  
J. M. Parker ◽  
J. K.W. Ferguson
Keyword(s):  
Carbonic Anhydrase ◽  
Dose Range ◽  
Carbonic Anhydrase Inhibitor ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
High Dose ◽  
Female Rat ◽  
Inhibitor Type ◽  
Almost All

The diuretic response of the male and the female rat to aminophylline has been studied when these animals were pretreated with various concentrations of sodium chloride solution. A linear log dose – response curve was obtained over the dose range employed with male rats pretreated with 0.45% and 2% saline. Male rats exhibited a diuresis with 4% saline which was not increased by aminophylline. Female rats showed diuresis but the responses were more variable for almost all combinations of electrolyte load and xanthine dose. When they were pretreated with 0.45% and 2% saline, aminophylline caused some additional production of urine but this was much less regular than that observed with males. The variation in response to aminophylline after 4% saline was very marked but the trend suggested that the xanthine had a diuretic effect at the high dose. The diuretic responses to a xanthine, a mercurial, and a carbonic anhydrase inhibitor type of diuretic were compared in the male rat. Peak responses were smallest after the mercurial diuretic and greatest with the carbonic anhydrase inhibitor.

scholarly journals Mode of GH administration and gene expression in the female rat brain

2017 ◽  
Vol 233 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Marion Walser ◽  
Linus Schiöler ◽  
Jan Oscarsson ◽  
Maria A I Åberg ◽  
Ruth Wickelgren ◽  
...  
Keyword(s):  
Mixed Model ◽  
Brain Regions ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Sexually Dimorphic ◽  
Female Rat ◽  
Expression Levels ◽  
Mixed Model Analysis ◽  
Significant Difference

The endogenous secretion of growth hormone (GH) is sexually dimorphic in rats with females having a more even and males a more pulsatile secretion and low trough levels. The mode of GH administration, mimicking the sexually dimorphic secretion, has different systemic effects. In the brains of male rats, we have previously found that the mode of GH administration differently affects neuron–haemoglobin beta (Hbb) expression whereas effects on other transcripts were moderate. The different modes of GH administration could have different effects on brain transcripts in female rats. Hypophysectomised female rats were given GH either as injections twice daily or as continuous infusion and GH-responsive transcripts were assessed by quantitative reverse transcription polymerase chain reaction in the hippocampus and parietal cortex (cortex). The different modes of GH-administration markedly increased Hbb and 5′-aminolevulinate synthase 2 (Alas2) in both brain regions. As other effects were relatively moderate, a mixed model analysis (MMA) was used to investigate general effects of the treatments. In the hippocampus, MMA showed that GH-infusion suppressed glia- and neuron-related transcript expression levels, whereas GH-injections increased expression levels. In the cortex, GH-infusion instead increased neuron-related transcripts, whereas GH-injections had no significant effect. Interestingly, this contrasts to previous results obtained from male rat cortex where GH-infusion generally decreased expression levels. In conclusion, the results indicate that there is a small but significant difference in response to mode of GH administration in the hippocampus as compared to the cortex. For both modes of GH administration, there was a robust effect on Hbb and Alas2.

Induction of the gonadotrophin surge-inhibiting factor by FSH and its elimination: a sex difference in the efficacy of the priming effect of gonadotrophin-releasing hormone on the rat pituitary gland

1993 ◽  
Vol 138 (2) ◽  
pp. 191-201
Author(s):  
D. W. Koppenaal ◽  
J. A. M. J. van Dieten ◽  
A. M. I. Tijssen ◽  
J. de Koning
Keyword(s):  
Body Weight ◽  
Pituitary Gland ◽  
Priming Effect ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Pulse Interval ◽  
Intact Female ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

ABSTRACT This study was designed to explore the efficacy of gonadotrophin-releasing hormone (GnRH) to antagonize the effect of gonadotrophin surgeinhibiting factor (GnSIF) on the timing of the induction by GnRH of the maximal self-priming effect on pituitary LH responsiveness. The GnSIF levels were increased by FSH treatment and reduced after gonadectomy. Female rats were injected s.c. with 10 IU FSH or saline (control) on three occasions during the 4-day cycle. Serial i.v. injections of GnRH (500 pmol/kg body weight) were administered to intact rats on the afternoon of pro-oestrus or 15–30 min after ovariectomy. Intact male rats were given 10 IU FSH and 500 or 2000 pmol GnRH/kg body weight on an equivalent time-schedule. Endogenous GnRH release was suppressed with phenobarbital. In intact female control rats, the timing of the maximally primed LH response was delayed as the GnRH pulse-interval increased. FSH treatment of female rats induced a suppression of the initial unprimed LH response and delayed the maximally primed LH response, which showed further delay as the GnRH pulse-interval was increased. When the pulsatile administration of GnRH was started 15–30 min after ovariectomy, the priming effect of GnRH did not change as the GnRH pulse-interval was increased in the saline-treated rats. However, FSH treatment caused a suppression of the unprimed LH response, a delay in the primed LH response and decreased the delay of the maximally primed LH response to GnRH when the GnRH pulse-interval was decreased. Increasing the interval between ovariectomy and the first GnRH pulse to 4 h diminished the efficacy of the FSH treatment: GnRH-induced priming was delayed by only one pulse instead of the two pulses in control rats. In intact males but not in orchidectomized rats, a self-priming effect was demonstrated during GnRH pulses which were 1 h apart. The effect of 2 nmol GnRH/kg body weight was the most pronounced. Compared with intact female rats, the timing of the maximally primed LH response was delayed by 1 h. FSH treatment did not affect the pituitary LH response to both dose levels of GnRH. It is concluded that FSH treatment increased the release of GnSIF by the ovary, then induced a state of low responsiveness of the pituitary gland to GnRH and subsequently delayed GnRH-induced maximal self-priming. The efficacy of GnRH to prime the pituitary gland was higher when GnSIF levels were decreasing after removal of the ovaries. On the other hand, GnSIF was more effective when the GnRH pulse-interval was increasing. This allows GnSIF more time to restore the unprimed state of the pituitary gland after each GnRH pulse-induced self-priming effect. It remains a matter of debate whether a similar mechanism of action is present in the male rat or whether this mechanism is suppressed by endogenous hormones such as androgens. Journal of Endocrinology (1993) 138, 191–201

EXPERIMENTAL EVALUATION OF DIURETICS IN THE RAT

1956 ◽  
Vol 34 (5) ◽  
pp. 903-911 ◽  
Author(s):  
J. D. McColl ◽  
J. M. Parker ◽  
J. K.W. Ferguson
Keyword(s):  
Carbonic Anhydrase ◽  
Dose Range ◽  
Carbonic Anhydrase Inhibitor ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
High Dose ◽  
Female Rat ◽  
Inhibitor Type ◽  
Almost All

The diuretic response of the male and the female rat to aminophylline has been studied when these animals were pretreated with various concentrations of sodium chloride solution. A linear log dose – response curve was obtained over the dose range employed with male rats pretreated with 0.45% and 2% saline. Male rats exhibited a diuresis with 4% saline which was not increased by aminophylline. Female rats showed diuresis but the responses were more variable for almost all combinations of electrolyte load and xanthine dose. When they were pretreated with 0.45% and 2% saline, aminophylline caused some additional production of urine but this was much less regular than that observed with males. The variation in response to aminophylline after 4% saline was very marked but the trend suggested that the xanthine had a diuretic effect at the high dose. The diuretic responses to a xanthine, a mercurial, and a carbonic anhydrase inhibitor type of diuretic were compared in the male rat. Peak responses were smallest after the mercurial diuretic and greatest with the carbonic anhydrase inhibitor.

Subacute co-exposure to low doses of ruthenium(III) changes the distribution, excretion and biological effects of silver ions in rats

2020 ◽  
Vol 17 (2) ◽  
pp. 163 ◽  
Author(s):  
Nicoleta Vedeanu ◽  
Cezara Voica ◽  
Dana Alina Magdas ◽  
Bela Kiss ◽  
Maria-Georgia Stefan ◽  
...  
Keyword(s):  
Biological Effects ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Human Organism ◽  
Critical Element ◽  
Female Rat ◽  
Low Doses ◽  
Subacute Toxicity ◽  
Liver And Kidney

Environmental contextAlthough ruthenium is a technology-critical element used in several new industries, little is known about its environmental impact or possible human health risks. We report a toxicological evaluation of laboratory animals during co-exposure to ruthenium and silver. We identified interactions between the two elements that could lead to unwanted biological effects. AbstractRuthenium is one of the rarest metals on Earth that is classified as a technology-critical element (TCE). Silver, however, is well known for its antibacterial and immunostimulant properties. The increasing use of Ru and Ag in medicine and daily life makes simultaneous exposure possible, with unknown pharmacokinetic or toxicological consequences for the human organism. Thus, the present study investigated the influence of co-exposure to RuIII on the subacute toxicity of Ag ions in rats after repeated daily administration for 28 days of low doses by oral gavage. The subacute toxicity was investigated by the evaluation of several biochemical and hematological parameters, evaluation of specific oxidative stress biomarkers from liver and kidney, and histopathological investigation of liver and kidney tissue samples after 28 days of exposure in female rats. In addition, Ag and Ru concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) in urine, liver and kidney parenchyma in male rats. The obtained results showed that co-exposure to low doses of RuIII and Ag did not produce any significant biochemical, hematological or histopathological alterations in the treated female rat groups, except for an increased red cell distribution width (RDW) value. A decrease of urinary excretion of Ag and of the Ag concentration in kidneys was observed in the male rat group co-exposed to RuIII and Ag. This is the first invivo study investigating the toxic effect of co-exposure to low doses of Ag and Ru ions, and the obtained results may justify further research on this subject, mainly on the investigation of possible competitive mechanisms.

THE »EARLY-ANDROGEN« SYNDROME; DIFFERENCES IN RESPONSE TO PRE-NATAL AND POST-NATAL ADMINISTRATION OF VARIOUS DOSES OF TESTOSTERONE PROPIONATE IN FEMALE AND MALE RATS

1964 ◽  
Vol 47 (1) ◽  
pp. 37-50 ◽  
Author(s):  
H. E. Swanson ◽  
J. J. van der Werff ten Bosch
Keyword(s):  
Critical Period ◽  
Ovarian Function ◽  
Testosterone Propionate ◽  
Single Injection ◽  
Male Rats ◽  
Male Rat ◽  
High Dose ◽  
Corpora Lutea ◽  
Female Rat ◽  
Time Of Administration

ABSTRACT The interaction between dose and time of administration of testosterone propionate (TP) on the development of sexual function was studied by giving a single dose of 5, 10, 50 or 500 μg TP to young rats of both sexes on the day of birth (day 1) or on day 2, 4 or 5. The effectiveness of androgen administration before birth was studied by giving a single injection of 2500 μg TP to pregnant rats on day 19 to 22 after conception. Pre-natal administration had no effect on the function of the ovaries of female offspring, although the dose was sufficient to cause masculinization of the external genitalia. The weight of the testes and accessories of the male offspring were not affected. The effects of post-natal TP administration on ovarian function varied with the dose and with the time of administration. Threshold doses (5 and 10 μg) were more effective the earlier they were given after birth. With these small doses, most of the rats had normal luteinized ovaries at 10 weeks and were able to bear and suckle normal litters. Some time later ovulations ceased so that at 21 weeks they were no longer fertile; at 27 weeks there were no more corpora lutea in the ovaries. In males, a dose of 50 μg of TP or more resulted in permanently reduced weight of testes, seminal vesicles and prostate. The earlier the treatment, the more marked was the depression of weight. From these results and others reported in the literature the following deductions can be made: (1) the critical period of brain sensitivity to physiological amounts of androgen probably lies between days 4 and 6 (day of birth counted as day 1); (2) a rough estimate of the amount of androgen secreted by the newborn male rat during the critical period would seem to be the equivalent of a single injection of 5–50 μg TP; (3) after the physiological critical period has elapsed a female rat can still be »masculinized« if a high dose of TP is given, up to a period of between 10–20 days after birth.

Sign in / Sign up

Export Citation Format

Share Document