scholarly journals Intracerebroventricular administration of the prolactin (PRL) receptor antagonist, S179D PRL, disrupts parturition in rats

Reproduction ◽  
2007 ◽  
Vol 134 (1) ◽  
pp. 155-160 ◽  
Author(s):  
B C Nephew ◽  
J Amico ◽  
H M Cai ◽  
A M Walker ◽  
R S Bridges
Keyword(s):  
Receptor Antagonist ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Plasma Progesterone ◽  
Blood Samples ◽  
Period Effects ◽  
Preliminary Study ◽  
Nulliparous Female ◽  
Plasma Prl

The prolactin (PRL) receptor antagonist S179D PRL delays the onset of maternal behavior in steroid-primed nulliparous female rats. The present study investigated the role of the neural PRL system in the process of parturition. A preliminary study indicated that S179D PRL treatments administered by ALZET minipump to the lateral ventricle severely disrupted parturition. To examine the likely causes of this disruption, a group of timed-pregnant catheterized rats was continuously infused with S-179D PRL (0.001 and 0.1 ng/h) or vehicle control to the lateral ventricles for 3 days (gestation days 21–23), and serial blood samples were taken throughout this period. Effects of the treatments on parturition were recorded, and blood samples were assayed for PRL, progesterone, and oxytocin. Significantly fewer S179D PRL-treated rats successfully delivered by 1500 h on day 23 of gestation when compared with controls. The higher dose of S179D PRL also significantly suppressed the prepartum rise in PRL throughout the prepartum period, while the lower dose only affected plasma PRL during the first 24 h of treatment. No significant effects of the antagonist on plasma progesterone or oxytocin were detected. We conclude that disruption of parturition by S179D PRL is not caused by significant alterations in the plasma concentrations of progesterone or oxytocin. S179D PRL may indirectly act on parturition through the modulation of prepartum PRL. These findings suggest a previously unrecognized role for PRL in the regulation of parturition.

Effects of antiserum to thyrotrophin-releasing hormone on the concentrations of plasma prolactin, thyrotrophin and LH in the pro-oestrous rat

1985 ◽  
Vol 104 (2) ◽  
pp. 205-209 ◽  
Author(s):  
A. M. Horn ◽  
H. M. Fraser ◽  
G. Fink
Keyword(s):  
Plasma Concentrations ◽  
Passive Immunization ◽  
Immune Serum ◽  
Female Rats ◽  
Plasma Prolactin ◽  
Thyrotrophin Releasing Hormone ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Sheep Blood

ABSTRACT The possible role of thyrotrophin-releasing hormone (TRH) in causing the pro-oestrous surge of prolactin was investigated in conscious female rats by passive immunization with a specific anti-TRH serum raised in sheep. Blood samples were withdrawn through a previously implanted intra-atrial cannula. The i.p. injection of 1 ml anti-TRH serum, but not non-immune sheep serum, at 13.00 h of pro-oestrus delayed by about 1 h the onset of the prolactin surge, but the peak of the surge was similar to that in animals injected with the non-immune serum. The plasma concentrations of TSH were significantly reduced by the anti-TRH serum, but plasma concentrations of LH were not significantly affected. These results show that TRH may play an important role in the timing and initiation, but not the maintenance of the prolactin surge in the pro-oestrous rat. J. Endocr. (1985) 104, 205–209

PLASMA PROLACTIN AND PROGESTERONE RESPONSES TO MATING ARE ALTERED IN AGED RATS

1981 ◽  
Vol 90 (2) ◽  
pp. 179-191 ◽  
Author(s):  
S. HENDRICKS ◽  
C. A. BLAKE
Keyword(s):  
Plasma Concentrations ◽  
External Jugular Vein ◽  
Female Rats ◽  
Plasma Prolactin ◽  
Aged Rats ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Plasma Progesterone ◽  
The One ◽  
The Right

The effects of varying amounts of copulatory stimulation on patterns of plasma concentrations of prolactin and progesterone were evaluated in 3- and 12-month-old female rats. The 12-month-old group included rats which still exhibited oestrous cycles and rats in persistent vaginal oestrus (PVO). The extent of copulatory stimulation was defined by the number of intromissions received during mating: ≤5,15 or > 50. Blood samples were drawn over the 8 days after mating through a cannula inserted into the right external jugular vein. Plasma from the samples was assayed for prolactin and progesterone. In aged but still cyclic rats, pregnancy rates were positively correlated with the number of intromissions received during mating. Only one rat in PVO became pregnant. All animals which became pregnant and rats in PVO which, after mating, exhibited a disruption of the pattern of PVO, showed the nocturnal surge of plasma prolactin characteristic of pregnant and pseudopregnant rats. While these surges persisted until day 8 after mating in pregnant animals, they were absent by this time in the rats in PVO. Prolactin surges were present in some but not all of the aged rats which did not become pregnant. Progesterone concentrations were raised in all pregnant animals except the one pregnant rat in PVO and, while not related to the number of intromissions, concentrations were higher 8 days after mating in young compared with those in aged pregnant rats. Plasma progesterone was low in rats in PVO regardless of disruption of the pattern of PVO. We have concluded that the failure of limited copulatory stimulation to induce pregnancy in older rats results, at least in part, from its failure to initiate nocturnal prolactin surges. Nevertheless, our data suggest that matings which are not experimentally limited should provide ample stimulation to establish such surges. Although reduced plasma concentrations of prolactin and progesterone at pro-oestrus and reduced plasma progesterone through part of gestation may contribute to decreasing fertility in aged rats, other unidentified factors appear to be involved in mediating the capacity of extensive copulatory stimulation to induce pregnancy in these animals.

scholarly journals Two strategies used to solve a navigation task: A different use of the hippocampus by males and females? A preliminary study in rats

2018 ◽  
Vol 39 (2) ◽  
pp. 319-339 ◽  
Author(s):  
Ferran Lugo ◽  
Marta N. Torres ◽  
V.D. Chamizo
Keyword(s):  
Dorsal Hippocampus ◽  
Female Rats ◽  
Male Rats ◽  
Males And Females ◽  
Preliminary Study ◽  
Types Of Information ◽  
Landmark Learning ◽  
Source Of Information ◽  
Geometry Learning

AbstractThere is abundant research (both in rodents and in humans) showing that males and females often use different types of information in spatial navigation. Males prefer geometry as a source of information, whereas females tend to focus on landmarks (which are often near to a goal objects). However, when considering the role of the hippocampus, the research focuses primarily on males only. In the present study, based on Rodríguez, Torres, Mackintosh, and Chamizo’s (2010, Experiment 2) navigation protocol, we conducted two experiments, one with males and another with females, in order to tentatively evaluate the role of the dorsal hippocampus in the acquisition of two tasks: one based on landmark learning and the alternate one on local pool-geometry learning. Both when landmark learning and when geometry learning, Sham male rats learned significantly faster than Lesion male animals. This was not the case with female rats in geometry learning. These results suggest that the dorsal hippocampus could play an important role in males only.

Attenuation of preovulatory gonadotrophin surges by epostane: a new inhibitor of 3β-hydroxysteroid dehydrogenase

1988 ◽  
Vol 118 (1) ◽  
pp. 59-68 ◽  
Author(s):  
L. V. DePaolo
Keyword(s):  
Peak Plasma ◽  
Plasma Concentrations ◽  
Hydroxysteroid Dehydrogenase ◽  
Inhibitory Effects ◽  
Plasma Progesterone ◽  
Ru 486 ◽  
Progesterone Secretion ◽  
Progesterone Antagonist

ABSTRACT Epostane, an inhibitor of 3β-hydroxysteroid dehydrogenase, was administered orally to pro-oestrous rats to evaluate further a possible role for preovulatory progesterone secretion in eliciting surges of LH and FSH. Whereas a dose of 10 mg epostane/kg had essentially no effects on preovulatory gonadotrophin surges and ovulation, 200 mg epostane/kg markedly attenuated LH and FSH surges and blocked ovulation. A dose of 50 mg epostane/kg exerted effects on LH and FSH surges and ovulation intermediate between those of doses of 10 and 200 mg/kg. Plasma concentrations of progesterone were significantly lower in all anovulatory epostane-treated rats at 18.00 and 22.00 h on pro-oestrus than those measured in vehicle-treated rats. Concurrent injection of 2 mg progesterone in rats given 200 mg epostane/kg restored gonadotrophin surges to normal, but consistently failed to reverse the inhibitory effects of epostane on ovulation. Peak plasma progesterone levels produced by the progesterone injections were eight- to tenfold higher than the highest levels measured in vehicle-treated rats during the afternoon of pro-oestrus. Insertion of progesterone capsules was less effective than injections of progesterone in restoring gonadotrophin surges to normal, even though peak plasma progesterone concentrations achieved after insertion of two 20 mm long progesterone capsules were double the peak progesterone concentrations measured in control rats. Nevertheless, taken together with recent reports showing attenuation of preovulatory gonadotrophin surges by the progesterone antagonist RU 486 (17β-hydroxy-11β-[4-dimethyl-aminophenyl]-17α-[prop-1-ynl]estra-4,9-diene-3-one), the present results provide support for a role of preovulatory progesterone secretion in enhancing oestrogen-dependent LH/FSH surges on pro-oestrus. J. Endocr. (1988) 118, 59–68

Cortisol, progesterone and β-endorphin response to stress in calves

1995 ◽  
Vol 75 (2) ◽  
pp. 197-201 ◽  
Author(s):  
C. Cooper ◽  
A. C. O. Evans ◽  
S. Cook ◽  
N. C. Rawlings
Keyword(s):  
Plasma Cortisol ◽  
Acute Stress ◽  
Plasma Concentrations ◽  
Farm Animals ◽  
Cortisol Secretion ◽  
Plasma Progesterone ◽  
Blood Samples ◽  
Stress Changes ◽  
Response To Stress ◽  
Assessment Of Stress

In evaluating stress in farm animals, it would be useful to know whether there were consistent endocrine responses that could be followed. Adrenal cortisol secretion is quite variable, but β-endorphin secretion and adrenal progesterone production may be useful indicators of stress. Changes in plasma concentrations of cortisol, β-endorphin and progesterone were studied in spring-born, castrated male calves (steers) (6 mo of age ± 18 d, 516 ± 26 kg, n = 12) subjected to the stress of routine dehorning. Steers were isolated from their dams for 2 h before headgate restraint (control) or restraint and dehorning. They were bled 60 and 10 min prior to headgate restraint or restraint and dehorning. Blood samples were also collected immediately after headgate restraint or restraint and dehorning (time 0) and 5, 10, 30 and 60 min later. All blood samples were taken from a jugular catheter, and the blood sampling that was done out of the headgate involved minimal manual restraint. Plasma β-endorphin concentrations were similar in control steers and dehorned steers (P > 0.05) and decreased significantly following restraint or restraint and dehorning (P < 0.05). Plasma cortisol concentrations rose significantly 5 min after dehorning and were elevated for 60 min; but with restraint only, plasma cortisol concentrations rose to a peak 5 min after release from chute restraint and then declined (P < 0.05). Plasma cortisol concentrations were greater in dehorned steers than in control steers in the period from 10 min after dehorning or headgate restraint to 60 min after headgate restraint (P < 0.0043). Plasma progesterone concentrations rose to a peak 10 min after dehorning and then declined, but in control steers, a peak was seen at 5 min after release from restraint (P < 0.05). Plasma progesterone concentrations were greater in dehorned steers between 5 and 60 min after dehorning than in control steers (P < 0.05). From these data, we concluded that in prepubertal, castrated male calves, β-endorphin was not released in any significant quantities in response to the stress of dehorning. In steers, adrenal cortisol and progesterone were secreted in response to acute stress, and a ratio of the two may provide a useful assessment of stress; this requires further study. Key words: Cortisol, progesterone, β-endorphin, stress, calves

scholarly journals Remote blood collection in reindeer (Rangifer tarandus tarandus L): a preliminary study

Rangifer ◽  
1994 ◽  
Vol 14 (1) ◽  
pp. 29 ◽  
Author(s):  
E. Wiklund ◽  
P.J. Goddard ◽  
C. Rehbinder
Keyword(s):  
Total Protein ◽  
Alanine Aminotransferase ◽  
Plasma Cortisol ◽  
Rangifer Tarandus ◽  
Plasma Concentrations ◽  
Blood Sampling ◽  
Blood Collection ◽  
Short Term ◽  
Blood Samples ◽  
Preliminary Study

Automatic blood sampling equipment (ABSE) was used successfully to collect blood samples from two reindeer. During blood sampling, two methods of restraint were applied which caused no short term changes in plasma concentrations of urea, aspartate aminotransferase, alanine aminotransferase or total protein. Plasma Cortisol concentrations were significantly elevated by the two restraint techniques. The value of ABSE in studies of stress in reindeer is discussed.

Endothelium and aortic contraction to endothelin-1 in the pregnant rat

2000 ◽  
Vol 78 (5) ◽  
pp. 372-377 ◽  
Author(s):  
Amadou Moctar Dièye ◽  
Alexis Gairard
Keyword(s):  
Receptor Antagonist ◽  
Late Pregnancy ◽  
Female Rats ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Endothelin 1 ◽  
Key Words Endothelin ◽  
Vasoconstrictor Peptide ◽  
Aortic Contraction

Endothelium-derived factors modulate tone and may be involved in hyporeactivity to vasoconstrictors, such as norepinephrine or angiotensin II, as has been previously described during gestation. The endothelium produces endothelin-1, a major vasoconstrictor peptide, therefore aortic contractions to endothelin-1 (10-10 to 3 ×10-7 M) were used to assess the role of the endothelium in pregnant Wistar rats (at 20 days of gestation). Late pregnancy is characterized by a significantly diminished systolic blood pressure in conscious rats (-17 mmHg, P < 0.001, n = 14). In pregnant and in age-matched nonpregnant female rats, endothelin-1 induced aortic contraction was greater when endothelium was present (at least P < 0.01). Indomethacin significantly reduced this contraction in aortic rings with intact endothelium in all groups. In aortic rings that had endothelium physically removed, contraction to endothelin-1 was greater in pregnant rats than in nonpregnant ones. Indomethacin decreased contraction of aortic rings in pregnant rats only. These results suggest an enhanced synthesis of vasoconstrictors by cyclooxygenases in vascular smooth muscle during pregnancy. In vessels with intact endothelium, we did not find hyporeactivity to endothelin-1 during late pregnancy. Contraction to endothelin-1 involved ETA receptors because it was decreased by BQ-123, an ETA receptor antagonist, whereas there was no significant change when using BQ-788, an ETB receptor antagonist. Key words: endothelin-1, endothelium, contraction, aorta, gestation.

Effect of acute immunoneutralization of endogenous leptin on prolactin and LH secretion during the afternoon of pro-oestrus or in steroid-treated ovariectomized female rats

Reproduction ◽  
2000 ◽  
pp. 39-45 ◽  
Author(s):  
LC Gonzalez ◽  
L Pinilla ◽  
M Tena-Sempere ◽  
C Dieguez ◽  
FF Casanueva ◽  
...  
Keyword(s):  
Prolactin Secretion ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Blood Samples ◽  
Lh Release ◽  
Lh Secretion

Recent data indicate that leptin is involved in the control of reproductive function. Experiments were carried out to analyse the role of endogenous leptin in the regulation of LH and prolactin secretion during the afternoon of pro-oestrus and that induced by ovarian steroids in ovariectomized rats. In the first experiment, cyclic female rats were implanted with intra-auricular and intracerebroventricular (i.c.v.) cannulae and, at pro-oestrus, were injected (i.c.v.) with 10 microliters normal rabbit serum or leptin antiserum (at 13:00 and 14:00 h). Blood samples were obtained at 10:00 h and at intervals of 1 h between 13:00 and 20:00 h. In the second experiment, female rats in pro-oestrus were injected with normal rabbit serum or leptin antiserum at 16:00 and 18:00 h and blood samples were taken every 10 min between 18:00 and 20:00 h. In the third experiment, adult female rats that had been ovariectomized 2 weeks before were implanted with intra-auricular and i.c.v. cannulae and treated with oestradiol benzoate (30 micrograms s.c.) at 10:00 h and progesterone (2 mg s.c.) 48 h later. Normal rabbit serum (10 microliters) or leptin antiserum (10 microliters) were injected (i.c.v.) at 13:00 and 14:00 h, and blood samples were obtained at 10:00 h and at intervals of 1 h between 13:00 and 20:00 h. In the fourth experiment, hemipituitaries from ovariectomized steroid-treated female rats were incubated in the presence of leptin116-130 (an active fragment of the native molecule), GnRH or leptin + GnRH. Prolactin and LH secretion during the afternoon of pro-oestrus in females treated with leptin antiserum was similar to that observed in animals injected with normal rabbit serum. In ovariectomized female rats, the steroid-induced LH surge increased slightly after administration of leptin antiserum, whereas the prolactin surge remained unchanged. In vitro, leptin116-130 (10(-5) to 10(-8) mol l-1) inhibited LH secretion and modulated the effect of GnRH on LH release, depending on the concentration of GnRH: leptin116-130 (10(-6) mol l-1) reduced the effectiveness of 10(-7) mol GnRH l-1 and increased that of 10(-9) mol GnRH l-1. In conclusion, these experiments indicate that acute immunoneutralization of endogenous leptin does not interfere with spontaneous or steroid-induced LH and prolactin surges. In addition, the finding that leptin116-130 inhibited LH release and modulated the effectiveness of GnRH in vitro provides evidence of the direct modulatory role of leptin on LH secretion acting at the pituitary.

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