Effect of an oral contraceptive on spontaneous running activity of female rats

1970 ◽  
Vol 48 (2) ◽  
pp. 107-114 ◽  
Author(s):  
M. J. Fregly ◽  
R. E. Hughes ◽  
C. E. Cox
Keyword(s):  
Drug Administration ◽  
Chronic Administration ◽  
Female Rats ◽  
Intact Female ◽  
Running Activity ◽  
Vaginal Cytology ◽  
Induced Changes ◽  
Chronic Drug Administration ◽  
Percent Decrease ◽  
Intact Rats

Dietary administration of Enovid® at 7.5 mg/kg of food for 11 days to intact female rats reduced their cyclic running activity and induced changes in vaginal cytology characteristic of estrus. There was a linear relationship between the logarithm of the dose of Enovid® ingested and the percent decrease in running activity from the average observed before drug administration. Dietary administration of norethynodrel, one of the two components of Enovid®, at 7.5 mg/kg of food for 21 days decreased the magnitude of the running activity slightly but failed to affect its cyclic nature. In contrast, dietary administration of mestranol at either 0.125 or 0.54 μg/kg of food for 24 and 29 days respectively reduced running activity and increased the length of the estrus cycle. Hence, the effect of Enovid® on the running activity of intact rats is probably attributable to the mestranol contained in it. An apparent escape from the effects of chronic administration of mestranol on spontaneous running activity was observed from 20 to 30 days after beginning treatment with either dose used. The escape was characterized by a reinitiation of cyclic running activity during chronic drug administration. Elucidation of the mechanism of the escape phenomenon will require further study.

Release and synthesis of FSH by pituitary glands of female rats in vitro

1982 ◽  
Vol 100 (4) ◽  
pp. 499-503 ◽  
Author(s):  
A. A. J. Jenner ◽  
J. de Koning ◽  
G. P. van Rees
Keyword(s):  
Protein Synthesis ◽  
Slow Rate ◽  
Female Rats ◽  
Intact Female ◽  
Ovx Rats ◽  
Basal Release ◽  
Pituitary Glands ◽  
Independent Synthesis ◽  
Intact Rats

Abstract. Anterior hemi-pituitary glands from intact female and ovariectomized (OVX) rats were incubated with or without a maximally effective dose of LRH. During an 8 h incubation, LRH-stimulated release of FSH by pituitary glands from intact rats was biphasic: an initial slow rate of release and, from 2 to 8 h, an enhanced rate of release. Basal release was low up to 4 h, after which a marked increase of the rate of release was measured: from 6 to 8 h there was no difference between the rates of basal and LRH-stimulated release. Basal and LRH-stimulated release of FSH by pituitary glands from OVX rats were high and approximately constant during an 8 h incubation. Both basal and LRH-stimulated release by glands from intact as well as OVX rats were protein synthesis dependent. During the incubations an LRH-independent synthesis of FSH was measured. The results suggest that this synthesis is involved, either directly or indirectly, in increasing the rate of basal release of FSH after 4 h. A comparison of release and synthesis of FSH with those of LH reveals characteristic differences.

Testosterone treatment of ovariectomized rats: Effects on lipolysis regulation in adipocytes

1990 ◽  
Vol 123 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Giovanni De Pergola ◽  
Agneta Holmäng ◽  
Jan Svedberg ◽  
Riccardo Giorgino ◽  
Per Björntorp
Keyword(s):  
Ovarian Function ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Fat Cell ◽  
Adrenergic Agonist ◽  
Intact Female ◽  
Testosterone Treatment ◽  
Catalytic Unit ◽  
Uk 14,304 ◽  
Intact Rats

Abstract. The effects of testosterone treatment (2 mg every 14 days, for three months) on adipocyte lipolysis of intact (250-300 g body weight) and ovariectomized female rats were studied. Testosterone treatment of intact rats had no effect. Ovariectomy was followed by an increase in fat cell size and a decrease of lipolysis stimulated by isoproterenol, norepinephrine, epinephrine, forskolin, cAMP and isobutylmethylxantine. The number of βadrenergic receptors was reduced. There was, however, no change in the antilipolytic effects of UK 14,304 (alpha2-adrenergic agonist), nicotinic acid, N6-phenylisopropyladenosine or insulin. Testosterone treatment of ovariectomized rats restored the number of β-adrenoceptors and lipolysis stimulated by cAMP and isobutylmethylxantine, but not lipolysis stimulated by catecholamines and forskolin, suggesting a remaining defect in the catalytic unit of adenylate cyclase. These results indicate that ovariectomy is followed by a profound derangement of the lipolytic pathway at several levels, from β-adrenoceptors number to the triglyceride lipase activity. This is partially restored by treatment with testosterone, which, however, has no effect on intact female rats. This study emphasizes the importance of ovarian integrity for the lipolytic regulation and the inability of testosterone to replace ovarian function in this regard or to affect lipolysis in intact female rats.

Incidence, growth and oestradiol-receptor levels of 7,12-dimethylbenz(a)anthracene-induced mammary tumours in rats: effects of neonatal sex steroids and oestradiol implants

1982 ◽  
Vol 95 (3) ◽  
pp. 357-368 ◽  
Author(s):  
G. Verhoeven ◽  
G. Vandoren ◽  
W. Heyns ◽  
E. R. Kühn ◽  
J. P. Janssens ◽  
...  
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Intact Female ◽  
Intact Male ◽  
Tumour Incidence ◽  
Tumour Induction ◽  
Male And Female Rats ◽  
Neonatal Administration ◽  
Low Levels ◽  
Intact Rats

The effects of neonatally administered steroids on the sensitivity of the mammary gland to tumour induction by 7,12-dimethylbenz(a)anthracene was studied as a model for delayed (de)differentiating effects of steroid hormones. Immediately after birth male and female rats were gonadectomized and treated with testosterone, oestradiol or oil. Control animals were left intact. On day 45 all the gonadectomized animals and some of the control animals received an implant which delivered continuous low levels of oestradiol. The carcinogen was administered on day 55. The administration of an oestradiol implant, which increased prolactin levels in all animals, markedly reduced tumour incidence in intact female rats and increased tumour incidence in intact male rats. Neonatal administration of testosterone or oestradiol did not significantly influence tumour incidence, histopathology or oestradiol responsiveness in neonatally gonadectomized rats but tended to decrease tumour oestradiol-receptor levels. This lack of effect of neonatal steroids in gonadectomized animals suggests that the effects observed by other authors in intact rats are mediated by changes in gonadal secretions. It is concluded that the hormonal environment during and after tumour induction plays a major role in the development of 7,12-dimethylbenz(a)anthracene-induced mammary carcinomas.

Dynamics of lysozyme activity in rat’s offspring before and after birth in intact rats and rats with painful stimulation at the day before the birth

2016 ◽  
Vol 21 (32) ◽  
pp. 8-12
Author(s):  
Абрамова ◽  
Marina Abramova ◽  
Алексеев ◽  
Vladimir Alekseev ◽  
Бойченко ◽  
...  
Keyword(s):  
Lysozyme Activity ◽  
Pregnant Female ◽  
Female Rats ◽  
Intact Female ◽  
Painful Stimulation ◽  
Before And After ◽  
Increased Activity ◽  
Stimulation Of ◽  
Intact Rats

Electrical painful stimulation of pregnant female rats at the day before the birth leads to an increased activity of lysozyme in rat’s offspring in the womb. No differences were found between lysozyme activity in the rat’s blood, which were born from intact female rats and female rats with electrical painful stimulation.

THE HYPOTHALAMUS AND PROPYLTHIOURACIL-INDUCED GOITRE IN THE RAT

1963 ◽  
Vol 42 (2) ◽  
pp. 254-262 ◽  
Author(s):  
J. J. van der Werff ten Bosch ◽  
H. E. Swanson
Keyword(s):  
Steady State ◽  
Thyroid Hormone ◽  
Adult Female ◽  
Normal Diet ◽  
Anterior Hypothalamus ◽  
Female Rats ◽  
Intact Rats

ABSTRACT Adult female rats were given a normal diet, or a diet which contained 0.15% propylthiouracil. At the beginning of the experiment one half of the rats were left intact, whilst the others received an electrolytic basal midline lesion in the anterior hypothalamus. Of each of the four groups of rats, one half was killed after 14 days, the others after 28 days. It was found (both after 14 and after 28 days) that the presence of a lesion reduced the thyroid weight to approximately 75% of the value in intact rats on the same diet, which might be normal or contain propylthiouracil. Propylthiouracil caused thyroid enlargement (to 278% after 14 days and 352–360% after 28 days) in intact rats as compared with intact rats on a normal diet, and in lesioned rats as compared with lesioned rats on a normal diet. It is concluded that lesions cause a lowered steady state of the thyroid-pituitary feed-back system, but that this system responds normally to the alteration of the steady state caused by the propylthiouracil-induced block in thyroid hormone output.

Hypothalamic regulation of reproduction under the chronic influence of toluene and melatonin

2021 ◽  
Vol 50 (2) ◽  
pp. 42-46
Author(s):  
G. O. Kerkeshko
Keyword(s):  
Biogenic Amines ◽  
Preoptic Area ◽  
Chronic Administration ◽  
Female Rats ◽  
Control Group ◽  
Simultaneous Administration ◽  
Chronic Effect ◽  
Circadian Variations ◽  
Hypothalamic Regulation ◽  
Maximal Permissible Concentration

Experiments on chronic administration of melatonin with and without chronic inhalation of toluene dosed at both maximal permissible concentration (50 mg/ml) and limited chronical range (500 mg/m3) have been carried out on female rats to discover their effects on biogenic amines system in hypothalamic structures related to gonadoliberin synthesis and secretion - preoptic area (PA) and median eminence (ME). Contents of biogenic amines in ME and especially in PA have been shown to have circadian variations with maximum in the morning in control group of rats.The chronic effect of synchronizing agent melatonin (administered dissolved in drinking water in concentration of 10 pg/m l, at night during 2 months) on neotransmitters and their circadian variations in both hypothalamic structures proved surprisingly to be much alike the effect of toluene. Both chemicals cause the disturbances of normal circadian variations o f norepinephrine, dopamine and serotonine in PA and dopamine in ME. The simultaneous administration of toluene and melatonin showed likewise no synchronizing ability of the latter under the conditions described.

scholarly journals Soy-Induced Fecal Metabolome Changes in Ovariectomized and Intact Female Rats: Relationship with Cardiometabolic Health

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Victoria J. Vieira-Potter ◽  
Tzu-Wen L. Cross ◽  
Kelly S. Swanson ◽  
Saurav J. Sarma ◽  
Zhentian Lei ◽  
...  
Keyword(s):  
Female Rats ◽  
Cardiometabolic Health ◽  
Intact Female

scholarly journals Impact of Gender and Age on Hyperthermia-Induced Changes in Respiration of Liver Mitochondria

Medicina ◽  
2018 ◽  
Vol 54 (4) ◽  
pp. 62 ◽  
Author(s):  
Giedrė Šilkūnienė ◽  
Rasa Žūkienė ◽  
Zita Naučienė ◽  
Laima Degutytė-Fomins ◽  
Vida Mildažienė
Keyword(s):  
Thermal Inactivation ◽  
Liver Mitochondria ◽  
Female Rats ◽  
Ros Generation ◽  
Age Group ◽  
Male And Female Rats ◽  
Gender And Age ◽  
Induced Changes ◽  
Gender Dependence ◽  
Malate Oxidation

Aim: This study aimed to compare hyperthermia-induced changes in respiration and generation of reactive oxygen species (ROS) in liver mitochondria derived from animals of different gender and age. Methods: The effects of hyperthermia (40–47 °C) on oxidation of different substrates and ROS production were estimated in mitochondria isolated from the liver of male and female rats of the 1–1.5, 3–4, or 6–7 months age. Results: Gender-dependent differences in response of respiration to hyperthermia were the highest at 3–4 months of age, less so at 6–7 months of age, and only minor at juvenile age. Mild hyperthermia (40–42 °C) stimulated pyruvate + malate oxidation in mitochondria of females, but inhibited in mitochondria of males in the 3–4 month age group. The resistance of mitochondrial membrane to hyperthermia was the highest at 3–4 month males, and the lowest in the 6–7 month age group. Inhibition of glutamate + malate oxidation by hyperthermia was caused by thermal inactivation of glutamate dehydrogenase. ROS generation at 37 °C was higher at 1–1.5 month of age, but the increase in ROS generation with rise in temperature in this age group was the smallest, and the strongest in 6–7 month old animals of both genders. Conclusions: The response to hyperthermia varies during the first 6–7 months of life of experimental animals: stronger gender dependence is characteristic at 3–4 months of age, while mitochondria from 6–7 months animals are less resistant to hyperthermia.

Pituitary Responsiveness to LH-Releasing Hormone in Intact Female Rats of Different Ages*

Endocrinology ◽  
1972 ◽  
Vol 90 (6) ◽  
pp. 1499-1502 ◽  
Author(s):  
LUCIANO DEBELJUK ◽  
AKIRA ARIMURA ◽  
ANDREW V. SCHALLY
Keyword(s):  
Female Rats ◽  
Intact Female ◽  
Releasing Hormone ◽  
Different Ages ◽  
Lh Releasing Hormone
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