DISAPPEARANCE RATE OF BOVINE PROLACTIN FROM PLASMA OF FEMALE RATS STUDIED AT INTERVALS OF UP TO 160 MINUTES BY RADIOIMMUNOASSAY

1970 ◽  
Vol 64 (4) ◽  
pp. 718-725 ◽  
Author(s):  
A. A. van der Gugten ◽  
H. G. Kwa
Keyword(s):  
Intravenous Administration ◽  
Female Rats ◽  
Disappearance Rate ◽  
Blood Samples ◽  
Dose Dependent

ABSTRACT Plasma values resulting from the intravenous administration of 300, 100, 30 and 10 μ of bovine prolactin to rats on day 1 of pregnancy were followed by taking blood samples after 10, 20, 40, 80 and 160 minutes respectively. The rate of disappearance was found to be dose-dependent and to vary in time in the same rat. It is suggested that at least two processes of elimination take place: 1. a (possibly excretory) process, which can bring »unphysiologically high« prolactin levels down to approximately its treshold level of 1.7 μg/ml and 2. a process, which breaks down the hormone into »immunoreactive« polypeptides. This process can degrade 10 μg of bovine prolactin quantitatively within 10 minutes, but appears to become rapidly »saturated« by larger amounts of the hormone.

Neonatal testosterone potentiates stimulated prolactin secretion in adult oestrogen-primed rats

1986 ◽  
Vol 109 (1) ◽  
pp. 57-60 ◽  
Author(s):  
R. G. Dyer ◽  
S. Mansfield
Keyword(s):  
Testosterone Propionate ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Neonatal Exposure ◽  
Adult Rats ◽  
Blood Samples ◽  
Before And After ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT Blood samples were collected from oestrogen-primed gonadectomized adult rats before and after electrical stimulation of the preoptic part of the hypothalamus. Six groups of rats were used for the experiments. These were (a) males castrated on the first day of life, (b) males castrated after puberty, (c) females ovariectomized after puberty and (d), (e) and (f) females given testosterone propionate at birth (1·25, 0·125 and 0·0125 mg/rat respectively). Neonatal exposure of the female rats to testosterone caused a dose-dependent increase in the amounts of prolactin released to levels significantly (P<0·01) higher than those observed in male animals and in untreated females. The results indicate that although neonatal testosterone inhibits oestrogen-stimulated prolactin secretion in adult rats, the neuroendocrine apparatus controlling secretion of the hormone is capable of being activated to greater effect after exposure to androgens at the time of birth. J. Endocr. (1986) 109, 57–60

Growth hormone (GH) secretion in the dwarf rat: release, clearance and responsiveness to GH-releasing factor and somatostatin

1990 ◽  
Vol 127 (1) ◽  
pp. 69-75 ◽  
Author(s):  
D. F. Carmignac ◽  
I. C. A. F. Robinson
Keyword(s):  
Low Dose ◽  
Gh Deficiency ◽  
Peak Plasma ◽  
Female Rats ◽  
Disappearance Rate ◽  
Gh Secretion ◽  
Fold Reduction ◽  
Plasma Gh ◽  
Age Range ◽  
Dose Dependent

ABSTRACT The new mutant GH-deficient dwarf (Dw) rat was used to study the effects of GH-releasing factor (GRF) or somatostatin (SRIF) on GH release. In anaesthetized adult Dw female rats, i.v. injections of GRF (0·031–2·0μg) elicited a dose-dependent release of GH. Although the peak plasma GH responses to maximal GRF doses were much lower in adult Dw rats compared with normal rats of this strain (AS), the responses largely reflected their relative pituitary GH contents (140±17 μg vs 2·9±0·4 μg, AS vs Dw (means ± s.e.m.), P < 0·001). Except at 20 days of age, normal AS rats were more sensitive to GRF than Dw rats despite their larger body weight. Peak GH responses to injection of 31·25 ng GRF increased nine-fold in normal rats between 20 and 40 days, whereas the GH responses to this GRF dose diminished in Dw rats over this age range, and their pituitary GH content was only 2–5% of that of age-matched AS rats. Treatment with human GH (200 μg/day for 7 days) stimulated growth in 40-day-old Dw rats and slightly increased the GH response to a low dose of GRF. Basal GH levels in adult Dw animals were sevenfold lower than in AS rats (2·4±0·3 vs 17·6±3·3 μg/l P < 0·001) and were further suppressed by i.v. infusion of SRIF (25 μg/h). As in normal rats, a rebound GH secretion occurred in Dw rats after stopping SRIF, which was blocked by injection of anti-GRF serum. The disappearance rate of 125I-labelled rat GH from plasma was identical in AS and Dw rats. We conclude that dwarf rats show GH deficiency as early as 20 days of age; they respond to GRF, but release only small amounts of GH due to their reduced pituitary GH content. Although basal GH release is reduced in Dw rats, the levels are higher than would be expected from the 50-fold reduction in pituitary stores, and may reflect a chronic reduction in SRIF and/or increase in GRF release induced by prolonged GH deficiency in the Dw rat. Journal of Endocrinology (1990) 127, 69–75

Serotonin stimulates GH secretion through a direct pituitary action: studies in hypophysectomized autografted animals and in perifused pituitaries

1986 ◽  
Vol 113 (3) ◽  
pp. 317-322 ◽  
Author(s):  
F. López ◽  
D. Gónzalez ◽  
E. Aguilar
Keyword(s):  
Plasma Volume ◽  
Direct Action ◽  
Experimental Models ◽  
Male Rats ◽  
Blood Samples ◽  
Kidney Capsule ◽  
Gh Secretion ◽  
Significant Release ◽  
The Right ◽  
Dose Dependent

Abstract. To analyze a possible direct action of serotonin (5-hydroxytryptamine) at pituitary level in GH secretion, two experimental models were used: hypophysectomized autografted rats and perifused pituitaries. Adult male rats were hypophysectomized and their own pituitaries placed under the right kidney capsule. Ten days later an intra-atrial cannula was inserted. The next day, blood samples were obtained before and every 10 min during a 2 h period after the injection of saline or 5-hydroxytryptamin (1 or 2 mg/kg iv). Plasma volume was replaced with saline. Both doses of 5-hydroxytryptamine elicit a strong release of GH, the effect being dose-dependent. In pituitaries perifused with 5-hydroxytryptamine (100 μm during 115 min or 1, 10 and 100 μm during 15 min), a significant release of GH was also observed. These results suggested that 5-hydroxytryptamine may stimulate GH secretion through a direct pituitary action.

Prolactin stimulates food intake in a dose-dependent manner

1989 ◽  
Vol 256 (1) ◽  
pp. R276-R280 ◽  
Author(s):  
T. Gerardo-Gettens ◽  
B. J. Moore ◽  
J. S. Stern ◽  
B. A. Horwitz
Keyword(s):  
Food Intake ◽  
Female Rats ◽  
High Dose ◽  
Dependent Manner ◽  
Additional Control ◽  
The Mean ◽  
Ovine Prolactin ◽  
Dose Dependent ◽  
Medium Dose ◽  
Cumulative Food Intake

Lactation in the rat is marked by pronounced hyperphagia and suppression of brown fat (BAT) thermogenic capacity. We previously examined the possibility that elevated prolactin levels mediate these changes. The present study evaluated the effect of varying prolactin levels on food intake, BAT mitochondrial GDP binding, and carcass adiposity. Female rats were injected daily for 10 days with ovine prolactin at one of three doses: high = 3.0, medium = 1.0, or low = 0.3 micrograms/g body wt. Controls were injected with 0.9% NaCl. A group of uninjected rats served as an additional control. Cumulative food intake was significantly elevated in a dose-dependent manner in the prolactin-treated animals relative to the saline-injected and uninjected controls. Compared with the saline controls, the mean cumulative food intake was greatest at the high dose (20% increase), intermediate at the medium dose (17%), and smallest at the low dose (12%). Prolactin-treated rats gained significantly more weight during the experiment than did controls. Despite the hyperphagia in the prolactin-treated rats, no significant differences in BAT mitochondrial GDP binding were observed among the five groups. These data indicate that elevated prolactin levels stimulate food intake in a dose-dependent manner and that this hyperphagia is not accompanied by an increase in BAT mitochondrial GDP binding.

scholarly journals Antidiarrheal Activity of Dissotis multiflora (Sm) Triana (Melastomataceae) Leaf Extract in Wistar Rats and Subacute Toxicity Evaluation

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Alian Désiré Afagnigni ◽  
Maximilienne Ascension Nyegue ◽  
Chantal Florentine Ndoye Foe ◽  
Youchahou Njankouo Ndam ◽  
Frédéric Nico Njayou ◽  
...  
Keyword(s):  
Wistar Rats ◽  
Leaf Extract ◽  
Shigella Flexneri ◽  
Female Rats ◽  
Male Rats ◽  
Dependent Manner ◽  
Subacute Toxicity ◽  
Antidiarrheal Activity ◽  
Dose Dependent ◽  
Ethanolic Leaf Extract

The present work was undertaken to evaluate antidiarrheal activity of ethanolic leaf extract of Dissotis multiflora (Sm) Triana (D. multiflora) on Shigella flexneri-induced diarrhea in Wistar rats and its subacute toxicity. Diarrhea was induced by oral administration of 1.2 × 109 cells/mL S. flexneri to rats. Antidiarrheal activity was investigated in rats with the doses of 111.42 mg/kg, 222.84 mg/kg, and 445.68 mg/kg. The level of biochemical parameters was assessed and organs histology examined by 14 days’ subacute toxicity. S. flexneri stool load decreased significantly in dose-dependent manner. The level of ALT increased (p<0.05) in male rats treated with the dose of 445.68 mg/kg while creatinine level increased in rats treated with both doses. In female rats, a significant decrease (p<0.05) of the level of AST and creatinine was noted in rats treated with the dose of 222.84 mg/kg of D. multiflora. Histological exams of kidney and liver of treated rats showed architectural modifications at the dose of 445.68 mg/kg. This finding suggests that D. multiflora leaf extract is efficient against diarrhea caused by S. flexneri but the treatment with doses lower than 222.84 mg/kg is recommended while further study is required to define the exact efficient nontoxic dose.

ANALYSIS OF MT2A AND MT3 GENE EXPRESSION IN RAT'S LIVER AND KIDNEY IN RESPONSE TO CADMIUM CHLORIDE POISONING

2021 ◽  
pp. 38-42
Author(s):  
M. M. Ziatdinova ◽  
T. G. Yakupova ◽  
Ya. V. Valova ◽  
G. F. Mukhammadieva ◽  
D. O. Karimov ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rat Liver ◽  
Cadmium Chloride ◽  
Transcriptional Activity ◽  
Female Rats ◽  
Expression Level ◽  
Cadmium Poisoning ◽  
Liver And Kidney ◽  
Dose Dependent ◽  
Higher Doses

The aim of this study was to investigate the expression of metallothionein genes in the liver and kidneys of rats with acute cadmium poisoning.Simulation of poisoning with cadmium chloride was carried out on white outbred female rats, divided into 4 groups depending on the dose of the injected toxicant. RNA samples isolated from rat liver and kidneys were used as research materials.The multiplicity of expression of the MT3 gene in the kidneys increased at the lowest dose of CdCl2 , which was used in this experiment (0.029 mg / kg); with increasing dosage, the expression level decreased, but not lower than the control values. Analysis of the expression of the same gene in the liver showed a tendency towards a decrease in the content of transcripts with increasing dose. The frequency of expression of the MT2A gene at higher doses of CdCl2 increased both in the liver and in the kidneys.In the present work, statistically significant dose-dependent changes in the expression multiplicity of metallothionein genes were detected 24 hours after CdCl2 administration. The revealed differences in the level of transcriptional activity of metallothionein genes require further investigation, since there are probably differences in the level of gene expression at earlier and later periods of toxicant action.

Ovarian steroid regulation of angiotensin II-induced water intake in the rat

1999 ◽  
Vol 276 (1) ◽  
pp. R90-R96 ◽  
Author(s):  
Lori R. Kisley ◽  
Randall R. Sakai ◽  
Li Yun Ma ◽  
Steven J. Fluharty
Keyword(s):  
Water Intake ◽  
Peptide Hormone ◽  
Estradiol Benzoate ◽  
Female Rats ◽  
Female Rat ◽  
Ang Ii ◽  
Concurrent Administration ◽  
Ovarian Steroid ◽  
Steroid Administration ◽  
Dose Dependent

Spontaneous water intake as well as thirst elicited by ANG II has been shown to be influenced by the stage of the estrous cycle in the female rat. In these experiments, the contribution of each of the ovarian steroid hormones to the regulation of water intake was examined. Ovariectomized female rats were given replacement doses of estrogen, progesterone, or both, and their responsiveness to an intracerebroventricular injection of ANG II was tested. Forty-eight-hour treatment with estradiol benzoate attenuated ANG II-induced thirst by as much as 70% compared with control animals. The effect of estrogen on drinking was dose dependent and could be completely blocked with concurrent administration of the antiestrogen CI-628. In contrast, progesterone, given alone or after estrogen, did not significantly affect ANG II-induced water intake when animals were tested at 4 or 24 h after steroid administration. A central interaction between the peptide hormone ANG II and estrogen, involving a genomic mechanism, may underlie the cyclicity in water intake behavior observed in the rat.

scholarly journals Subchronic toxicity of aqueous extract of Alstonia boonei de wild. (apocynaceae) stem bark in normal rats

2015 ◽  
Vol 3 (1) ◽  
pp. 5 ◽  
Author(s):  
Barnabé Lucien Nkono Ya Nkono ◽  
Selestin Dongmo Sokeng ◽  
Paul Désiré Dzeufiet Djomeni ◽  
Frida Longo ◽  
Pierre Kamtchouing
Keyword(s):  
Aqueous Extract ◽  
Biochemical Study ◽  
Female Rats ◽  
Male Rats ◽  
Control Group ◽  
Control Male ◽  
Control Female ◽  
Hematological Analysis ◽  
Wbc Count ◽  
Dose Dependent

<p><strong>Methodology:</strong> Wistar rats were randomly assigned into eight groups of five animals each: four male groups and four female groups. Each sex group had a control group receiving distilled water and three test groups receiving 200, 500 and 1000mg/kg respectively. Animal’s body weights were recorded on the first day and once a week for the four experiment weeks. The hematological analysis included total WBC count, total RBC count, Hb, %HCT, MCV, MCH and MCHC. Biochemical/serum profile studies include TG, TC, ALT, AST, urea and TP. Tissue specimens of the liver, kidney and lung were subjected to histological examination using standard hematoxylin-eosin staining.</p><p><strong>Results:</strong> In male rats, aqueous extract showed significant decreases in relative weight of liver with extreme significance P&lt;0.001 at a dose of 200mg/kg (vs. control group), P&lt;0.001 of lung at all the doses, P&lt;0.05 (200 and 500mg/kg) and P&lt;0.01 (1000mg/kg) in heart weight. In relative kidney weight, only the dose of 1000mg/kg showed a significant increase vs. normal control male rats. Unlike male rats, only relative kidney weight in female rats was significantly different from the control group in a dose-dependent manner. The aqueous extract treated male groups showed significant increases P&lt;0.001 (1000mg/kg) of total WBC count and MCHC, significant decreases of %HTC (dose response manner), P&lt;0.05 total RBC count (at doses of 500 and 1000mg/kg) and Hb P&lt;0.01 (500mg/kg) vs. normal male rats. In female rats, the haematological study showed significant increase P&lt;0.01 of total WBC count (at the doses of 500 and 1000mg/kg), significant decreases P&lt;0.05 and P&lt;0.01 of total RBC respectively at the doses of 200 and 1000mg/kg, significant decrease of Hb with extreme significance P&lt;0.001 at the dose 1000mg/kg, %HTC also decrease dose response manner vs. control female rats. Biochemical study showed in male rats significant decreases in level of TG P&lt;0.001 (at the doses of 200 and 500mg/kg) and urea, although it showed any dose-dependent effect vs. control male rats. AST also decreases (P&lt;0.05) in male rats at the dose of 200mg/kg but significantly increase P&lt;0.001 at the dose of 500mg/kg. In the female rats, biochemical study revealed significant increases in level of TG P&lt;0.001 and urea P&lt;0.01 at the dose of 200mg/kg and significant decreases in level of TG P&lt;0.01, AST P&lt;0.05 and urea P&lt;0.05 at the dose of 500mg/kg (vs. control female rats). Microscopically, there were mild hepatic and renal tissue injuries supporting the hematological analysis.</p><p><strong>Conclusion:</strong> The results indicated that aqueous extract of <em>Alstonia boonei</em> De Wild is toxic in high doses.</p>

scholarly journals Oestrogen-Dependent Oxytocin Dynamics in the Hypothalamus of Female Rats

2021 ◽  
Author(s):  
Kazuaki Nishimura ◽  
Kiyoshi Yoshino ◽  
Naofumi Ikeda ◽  
Kazuhiko Baba ◽  
Kenya Sanada ◽  
...  
Keyword(s):  
Systemic Circulation ◽  
Female Rats ◽  
Dependent Manner ◽  
Transgenic Rats ◽  
Dynamic Changes ◽  
Hypothalamic Nuclei ◽  
The Central Nervous System ◽  
Posterior Pituitary Gland ◽  
Dose Dependent ◽  
Ovariectomised Rats

Abstract Oxytocin (OXT) is produced in the hypothalamic nuclei and is secreted into systemic circulation from the posterior pituitary gland (PP). In the central nervous system, OXT regulates behaviours including maternal and feeding behaviours. Our aim was to evaluate whether oestrogen regulates hypothalamic OXT dynamics. Herein, we provide the first evidence that OXT dynamics in the hypothalamus vary with sex and that oestrogen may modulate dynamic changes in OXT levels, using OXT-mRFP1 transgenic rats. The fluorescence intensity of OXT-mRFP1 in the hypothalamic nuclei and PP was most strongly expressed during the oestrus stage in female rats and decreased significantly in ovariectomised rats. Oestrogen replacement caused significant increases in the fluorescent intensities in the hypothalamic nuclei and PP in a dose-dependent manner. This was also demonstrated in feeding behaviour and hypothalamic Fos neurons using immunohistochemistry. Hypothalamic OXT expression was oestrogen dependent and could be enhanced centrally by the administration of oestrogen.

scholarly journals Prooxidant and antioxidant activity of blood plasma and histology of internal organs of rats after intravenous administration of magnetite nanoparticles

2013 ◽  
Vol 59 (3) ◽  
pp. 330-338 ◽  
Author(s):  
I.V. Milto ◽  
T.K. Klimenteva ◽  
I.V. Suhodolo ◽  
N.A. Krivova
Keyword(s):  
Antioxidant Activity ◽  
Blood Plasma ◽  
Intravenous Administration ◽  
Magnetite Nanoparticles ◽  
The Body ◽  
Antioxidant Systems ◽  
Internal Organs ◽  
Intravenous Injections ◽  
Magnetite Particles ◽  
Dose Dependent

The effect of a single and multiple intravenous injections of a nanosized magnetite suspension on total prooxidant and antioxidant activity of blood plasma has been investigated by the method of luminol-dependent chemoluminescence. Magnetite nanoparticles possess dose-dependent prooxidant properties due to their iron atoms and at the same time their trigger compensatory activation of antioxidant systems in the rat blood plasma. After a single intravenous administration of magnetite the studied parameters of blood plasma returned to the normal level by the end of the experiment as due to removal of nanoparticles from the body. In the case of multiple administration of the magnetite suspension dose-dependent changes in the pro- and antioxidant plasma activity persist during the whole experiment. Accumulation of magnetite particles in the cells of the mononuclear phagocytic system in the rats’ liver, lungs and kidneys is associated with hemodynamic damages, local dystrophic and necrotic changes of parenchyma in these organs. After a single intravenous injection magnetite nanoparticles are identified in the rat organs for 40 days, but their number decreases by the end of the experiment.

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