Mechanisms of action of testosterone propionate on LH and FSH release by the pituitary gland in cyclic female rats

1980 ◽  
Vol 95 (2) ◽  
pp. 158-165 ◽  
Author(s):  
J. Roos ◽  
S. Plas-Roser ◽  
Cl. Aron
Keyword(s):  
Pituitary Gland ◽  
Sharp Increase ◽  
Testosterone Propionate ◽  
Sharp Decrease ◽  
Mechanisms Of Action ◽  
The Other ◽  
Female Rats ◽  
Corpora Lutea ◽  
Other Hand ◽  
Lh Release

Abstract. The aim of this work was to determine whether changes in pituitary responsiveness to LRH could account for the effect of testosterone propionate (TP) on the gonadotrophic function of the pituitary in 4-day cyclic female rats. Doses of 250, 500 and 1000 ng LRH were injected ip on pro-oestrus at 15.30 h in rats either pre-treated with 5 mg TP on dioestrus II at 10.00 h or injected with 30 mg/kg pentobarbital (PB) at 13.00 h. LH release induced within 30 min by LRH was higher in PB than in TP-treated rats. Even by using 250 ng LRH full ovulation was observed on the morning of oestrus in PB-treated rats. On the other hand, only partial ovulation occurred whatever the dose of LRH used in TP-treated rats; a great number of luteinized follicles was shown to be constantly associated with post-ovulatory corpora lutea. While LRH caused a significant FSH release (30 min later) in TP-treated rats, no FSH release could be shown in PB-treated rats. The pituitary FSH content appeared to be decreased and the pituitary LH content remained unchanged while a sharp increase in both blood FSH and LH concentrations occurred following injection of 1000 ng LRH in TP-treated rats. Concomitantly a sharp decrease in the number of pituitary gonadotrophs (AB-PAS+) was observed. A significant decrease in the number of the small roundshaped PAS positive cells was also observed. The mechanisms whereby TP influences the function of the pituitary-ovarian axis are discussed in the light of these results.

scholarly journals Predominant androgenic component in the stimulatory effect of dehydroepiandrosterone on bone mineral density in the rat

1998 ◽  
Vol 157 (3) ◽  
pp. 433-442 ◽  
Author(s):  
C Martel ◽  
A Sourla ◽  
G Pelletier ◽  
C Labrie ◽  
M Fournier ◽  
...  
Keyword(s):  
Trabecular Bone ◽  
Bone Mineral ◽  
Bone Volume ◽  
The Other ◽  
Female Rats ◽  
Trabecular Bone Volume ◽  
A Value ◽  
Other Hand ◽  
Dhea Treatment ◽  
Trabecular Number

In order to assess the relative roles of the androgenic and/or estrogenic components in the stimulatory effect of dehydroepiandrosterone (DHEA) on bone mineral content (BMC) and density (BMD), ovariectomized (OVX) female rats received DHEA administered alone or in combination with the antiandrogen flutamide (FLU) or the antiestrogen EM-800 for 12 months. We also evaluated, for comparison, the effect of estradiol (E2) and dihydrotestosterone (DHT) constantly released by Silastic implants as well as medroxyprogesterone acetate (MPA) released from poly(lactide-co-glycolide) microspheres. Femoral BMD was decreased by 11% 1 year after OVX, but treatment of OVX animals with DHEA increased BMD to a value 8% above that of intact animals. The administration of FLU reversed by 76% the stimulatory effect of DHEA on femoral BMD and completely prevented the stimulatory effect of DHEA on total body and lumbar spine BMD. Similar results were obtained for BMC. On the other hand, treatment with the antiestrogen EM-800 did not reduce the action of DHEA on BMD or BMC. At the doses used, MPA, E2 and DHT increased femoral BMD, but to a lesser degree than observed with DHEA. Bone histomorphometry measurements were also performed. While DHEA treatment partially reversed the marked inhibitory effect of OVX on the tibial trabecular bone volume, the administration of FLU inhibited by 51% (P < 0.01) the stimulatory effect of DHEA on this parameter. The addition of EM-800 to DHEA, on the other hand, increased trabecular bone volume to a value similar to that of intact controls. DHEA administration markedly increased trabecular number while causing a marked decrease in the intertrabecular area. The above stimulatory effect of DHEA on trabecular number was reversed by 54% (P < 0.01) by the administration of FLU, which also reversed by 29% the decrease in intertrabecular area caused by DHEA administration. On the other hand, the addition of EM-800, while further decreasing the intertrabecular space achieved by DHEA treatment, also led to a further increase in trabecular number to a value not significantly different from that of intact control animals, suggesting an additional effect of EM-800 over that achieved by DHEA. Treatment with DHEA caused a 4-fold stimulation of serum alkaline phosphatase, a marker of bone formation, while the urinary excretion of hydroxyproline, a marker of bone resorption, was decreased by DHEA treatment. Treatment with DHEA and DHEA + EM-800 decreased serum cholesterol levels by 22 and 65% respectively, while the other treatments had no significant effect on this parameter. The present data indicate that the potent stimulatory effect of DHEA on bone in the rat is mainly due to the local formation of androgens in bone cells and their intracrine action in osteoblasts.

scholarly journals Stimulation of the corpora lutea of the rat by means of progesterone and testosterone

1937 ◽  
Vol 124 (836) ◽  
pp. 362-368 ◽  
Keyword(s):  
Guinea Pigs ◽  
Rhesus Monkeys ◽  
Testosterone Propionate ◽  
Female Rats ◽  
Corpora Lutea ◽  
Normal Female ◽  
Once Daily ◽  
Black And White ◽  
White Rats ◽  
Stimulation Of

The administration of progestin or progesterone inhibits oestrus in normal female experimental animals and leads to the cessation of follicular growth (Papanicolaou 1926, working on guinea-pigs; Gley 1928, on rats; Corner 1935, on monkeys). Active testicular extracts or testosterone have a similar effect (Ihrke and D’Amour 1931; Lendle 1931; and Robson 1936, working on rats; Zuckerman 1937, on rhesus monkeys). There is evidence that a phase of luteal activity occurs whenever the ripening of follicles is inhibited (see Evans 1928; Weichert 1930, amongst others), and it was therefore of interest to enquire whether or not luteinization of the ovaries is also an effect of the administration of progesterone and testosterone to normally cyclic female rats. Previous reports on this question are negative. Papanicolaou (1926) observed degenerative changes in the ovaries of guinea-pigs in which several successive oestrous cycles had been suppressed by means of progestin. Selye, Browne and Collip (1936) injected six rats with 4 mg. of progesterone for 12 days, and at the close of the experiment found that neither recent corpora lutea nor mature follicles were present in the ovaries. Albino and black and white rats were used. All injections were given once daily and subcutaneously. Oestrone was administered in aqueous solution, and both progesterone and testosterone propionate in oil. At the end of each experiment the uterus and one of the ovaries were fixed in Bouin’s fluid, and after sectioning, stained with haematoxylin and eosin, the ovary being sectioned serially. The second ovary of each animal was fixed in Flemming’s chrome-osmium fluid with acetic acid, and prepared to show osmicated fats according to the technique described by Deanesly (1930). In certain cases, noted below, the uterus was traumatized by the method of Shelesnyak (1933α) (a modification of that of Long and Evans), in order to produce deciduomata.

scholarly journals Essential Oil of Piper Purusanum C.DC (Piperaceae) and Its Main Sesquiterpenes: Biodefensives Against Malaria and Dengue Vectors, Without Lethal Effect on Non-target Aquatic Fauna

2022 ◽  
Author(s):  
André C. de Oliveira ◽  
Rejane C. Simões ◽  
Carlos A. P. Lima ◽  
Felipe M. A. da Silva ◽  
Sergio M. Nunamura ◽  
...  
Keyword(s):  
Essential Oil ◽  
Lethal Effect ◽  
Mechanisms Of Action ◽  
The Other ◽  
Egg Hatching ◽  
Aquatic Fauna ◽  
Other Hand ◽  
Germacrene D ◽  
Promising Source ◽  
Dengue Vectors

Abstract The mosquitoes vectors of the genus Aedes and Anopheles present resistance to several commercial insecticides, which are also toxic to non-predators targets. On the other hand, essential oils are a promising source of insecticides. Thus, in this work, the essential oil from the leaves of Piper purusanum was characterized by gas chromatography based approaches and evaluated as biodefensive against malaria and dengue vectors. The main compounds of P. purusanum essential oil were β-caryophyllene (57.05%), α-humulene (14.50%) and germacrene D (8.20%). The essential oil inhibited egg hatching (7.6 ± 1.5 to 95.6 ± 4.5%) caused larval death (LC50 from 49.84 to 51.60 ppm) and inhibited the action of acetylcholinesterase (IC50 of 2.29 µg/mL), which can be related to the mechanisms of action. On the other hand, the biological activity of β-caryophyllene, α-humulene and germacrene D were higher than the essential oil. In addition, these sesquiterpenes and essential oil did not show a lethal effect on Toxorhynchites splendens, Anisops bouvieri, Gambusia affinis and Diplonychus indicus (LC50 from 2098.80 to 7707.13 ppm), although D. indicus is more sensible (SI/PSF from 48.56 to 252.02 ppm) to essential oil, representing a natural alternative against these relevant vectors.

Plasma prolactin in the rat during suckling without prior separation from pups

1985 ◽  
Vol 108 (4) ◽  
pp. 468-474 ◽  
Author(s):  
John A. M. Mattheij ◽  
Hans J. M. Swarts ◽  
Simone van Mourik
Keyword(s):  
Pituitary Gland ◽  
The Other ◽  
Plasma Prolactin ◽  
Low Level ◽  
Litter Removal ◽  
Other Hand ◽  
Plasma Prl ◽  
Secretory Capacity

Abstract. The relation between suckling and plasma prolactin (Prl) was studied in the rat, without prior separation of the dam from its pups. When the pups were replaced by a hungry foster litter, upon renewed suckling plasma Prl showed episodic increases and decreases in individual rats. When, subsequent to litter removal, similar rats were injected with perphenazine, a significant increase of plasma Prl was observed. This indicates that a decline of plasma Prl during suckling was not caused by exhaustion of Prl stores in the pituitary. In 22 individual rats blood was sampled every other minute while observations were made on nursing behaviour of the dams. During apparent suckling, increases as well as decreases of plasma Prl occurred. However, in most cases suckling did not affect plasma Prl, i.e. it remained stable at a high or a relatively low level. On the other hand, a considerable rise of plasma Prl was frequently observed when a dam was away from the nest. The data indicate that in the physiological situation Prl secretion from the pituitary is not directly related suckling activity, though episodes of suckling are essential to maintain a high Prl secretory capacity of the pituitary gland.

The synthesis and release of gonadotropins in response to gonadotropin-releasing hormone of the rat anterior pituitary gland during weight reduction

1990 ◽  
Vol 122 (5) ◽  
pp. 628-632 ◽  
Author(s):  
Fumikazu Kotsuji ◽  
Takeshi Aso ◽  
Naoyuki Kamitani ◽  
Toshiro Tominaga
Keyword(s):  
Weight Loss ◽  
Pituitary Gland ◽  
Weight Reduction ◽  
Female Rats ◽  
Serum Lh ◽  
Female Wistar Rats ◽  
Progressive Weight Loss ◽  
Lh Release ◽  
Lh Secretion

Abstract. It is well recognized that weight reduction produces the suppression of serum LH but not FSH level in rodents. In order to clarify the mechanism by which the discrepancy between LH and FSH levels is brought about, the influence of weight loss on the pituitary function was explored using female rats. The changes of the pituitary response to GnRH and the basal secretion of gonadotropins with progressive weight loss were investigated by in vitro short-term incubation of the pituitary gland after prolonged weight loss in female Wistar rats. On the first day of diestrous and until day 14 of the diet, GnRH induced LH and FSH release from the pituitary and a decrease in pituitary content of them, but the total amount of gonadotropin in culture medium and pituitary tissue was not affected. On day 30 of the diet, the decrease in pituitary content disappeared. On day 60 LH release disappeared, whereas pituitary FSH and the total amount of gonadotropins were increased by GnRH. Non-stimulated FSH but not LH secretion per mg of pituitary was augmented during dieting. The data indicate that pituitary responsiveness to GnRH and non-stimulated FSH release were modified by weight loss: the LH-releasing action of GmRH was diminished, the gonadotropin-synthesizing action of GnRH was augmented, and non-stimulated FSH release was increased.

THE UPTAKE OF 17β-OESTRADIOL IN BREAST TISSUE OF FEMALE RATS

1968 ◽  
Vol 58 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Sten Sander
Keyword(s):  
Skeletal Muscle ◽  
Direct Effect ◽  
Breast Tissue ◽  
The Other ◽  
Female Rats ◽  
Competitive Effect ◽  
Simultaneous Injection ◽  
Other Hand ◽  
Uptake Pattern ◽  
Wet Weight

ABSTRACT The uptake of radioactivity in breast tissue after the injection of tritiated oestradiol in rats has been studied. The breast tissue accumulates more radioactivity per unit wet weight than skeletal muscle and fat, for at least 4 hours. The uptake of radioactivity does not, however, reach the high levels observed in the uterus. On the other hand, the uptake pattern found in the breast tissue corresponds to previous findings in other oestrogen responsive organs. The uptake of radioactivity by breast tissue in castrated rats is higher than in control animals with their ovaries intact. It is also found that simultaneous injection of non-radioactive oestradiol reduces the uptake of radioactivity. These findings may be explained as a competitive effect between non-labelled and labelled oestradiol. The accumulation of oestradiol observed may be consistent with the idea of a direct effect on breast tissue.

Crimmigration and the prison: Comparing trends in prison policy and practice in England & Wales and Norway

2017 ◽  
Vol 14 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Francis Pakes ◽  
Katrine Holt
Keyword(s):  
Sharp Increase ◽  
Western Europe ◽  
The Other ◽  
Policy And Practice ◽  
Theoretical Understanding ◽  
Foreign Nationals ◽  
Other Hand ◽  
Prison Policy ◽  
Prison Systems ◽  
The Uk

The crimmigration landscape in the UK is much lamented. Reference is frequently made to the recent creation of dozens of new immigration offences and a sharp increase in the administrative detention of immigrants during the last two decades. In particular, the prison has recently become an acute site of crimmigration, with separate prisons for foreign nationals (Kaufman, 2013). Norway, on the other hand, has traditionally been regarded as an exception. The treatment of criminals and outsiders is described as inclusive and rehabilitative and focused on their successful return to society. However, here a distinction is also increasingly made between prisoners who will return to society and those who will not, most particularly foreign nationals. The UK and Norway are virtually the only countries in Western Europe with regular prisons that are exclusively reserved for foreign nationals. This article examines how the arguably most benign and the arguably most severe prison systems of Western Europe have come to mimic each other in this fashion. Wider implications for our theoretical understanding of the nature and loci of crimmigration policies are also considered.

THE EFFECT OF NORETHYNODREL ON THE OVARIES AND PITUITARY GLAND OF ADULT FEMALE RATS

1962 ◽  
Vol 24 (4) ◽  
pp. 497-515 ◽  
Author(s):  
R. L. HOLMES ◽  
ANITA M. MANDL
Keyword(s):  
Pituitary Gland ◽  
Dose Level ◽  
Adult Female ◽  
Female Rats ◽  
Prolonged Treatment ◽  
Corpora Lutea ◽  
Variable Degree ◽  
Vaginal Smears ◽  
Stages Of Development

SUMMARY Prolonged treatment with norethynodrel at a dose level sufficient to cause sterility did not consistently lead to blocking of ovulation. The ovaries of some of the animals were devoid of corpora lutea, while those of others contained variable numbers at different stages of development and regression. None of the treated animals, however, possessed as many corpora lutea as did their oil-injected controls. The treatment also induced a variable degree of follicular inhibition. Typical and regular oestrous cycles were abolished. The incidence of corpora lutea formed during the period of injection was slightly greater in animals housed with males than in those kept isolated. Although coitus was not followed by a period of pseudopregnancy, as judged by vaginal smears, most of the mated animals possessed corpora lutea resembling those of pseudopregnancy. The pituitary gland of the norethynodrel-treated animals was heavier than that of their controls, due largely to an increase in the volume of tissue occupied by chromophobe cells. The proportion of basophil cells was lower, while that of eosinophil cells remained unchanged.

RELATIONSHIP BETWEEN THE PITUITARY GLAND AND GONADAL STEROIDS: INVOLVEMENT OF A HYPOPHYSIAL FACTOR IN REDUCED α2u-GLOBULIN AND INCREASED TRANSCORTIN CONCENTRATIONS IN RAT SERUM

1978 ◽  
Vol 78 (1) ◽  
pp. 31-38 ◽  
Author(s):  
G. VANDOREN ◽  
H. VAN BAELEN ◽  
G. VERHOEVEN ◽  
P. DE MOOR
Keyword(s):  
Pituitary Gland ◽  
Testosterone Propionate ◽  
Single Injection ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Male Rats ◽  
Rat Serum ◽  
Mediated Effects ◽  
Male And Female Rats ◽  
Oestradiol Benzoate

Evidence is presented that the level of α2u-globulin in the serum of male rats depends, at least in part, on neonatal androgens. After castration of adult animals the concentration of this protein falls but remains measurable, whereas in intact or ovariectomized female rats α2u-globulin cannot be detected. Moreover, α2u-globulin is found in adult male and female rats gonadectomized at birth and treated with a single injection of testosterone propionate immediately thereafter. The mechanism by which neonatal androgens increase the concentration of α2u-globulin has been investigated. Transplantation of a supplementary pituitary gland under the renal capsule of male rats resulted in reduced levels of α2u-globulin and increased levels of transcortin. The changes discussed here were observed only in those animals in which the transplant was functional and they were amplified or reversed by modulators of prolactin secretion such as oestrogens or bromocriptine respectively. The hypothesis is advanced that neonatal androgens stimulate the production of a hypothalamic inhibitory factor that controls the secretion of prolactin, or another hypophysial hormone subjected to similar neuroendocrine control. Measurements in gonadectomized animals and in rats receiving both oestradiol benzoate and bromocriptine indicate that, besides these pituitary-mediated effects, both oestrogens and androgens exert direct effects on the level of α2u-globulin.

scholarly journals Review of Developments in the Pakistan Economy

1962 ◽  
Vol 2 (1) ◽  
pp. 114-127
Author(s):  
A. M. G. A. M. G.
Keyword(s):  
Sharp Increase ◽  
The Other ◽  
Supply Situation ◽  
Price Fluctuations ◽  
Other Hand ◽  
Medium Quality ◽  
New Crop ◽  
Wheat Price

Prices of wheat and rice showed divergent trends during the period October to December 1961. While prices of wheat in the Lyallpur market recorded a net advance of Rs. 0.25 per maund over the period under review, prices of rice (msdium quality) in the Dacca market registered a net decline of Rs. 3.60 per maund. In the case of wheat, price fluctuations were small and there was no deterioration in the overall supply situation. Moreover, as compared with prices a year ago, the end-December 1961 prices were around Rs. 1.25—2.00 per maund lower at Rs. 14.00—16.25 per maund. On the other hand, a sharp increase in the prices of rice at Dacca from Rs. 32.40 per maund at the close of September to Rs. 37.60 in October was held in check only after the release of government-held stocks. Subsequently, prices fell persistently when the 'aman' crop was harvested and the market received continued inflow of the new crop. By the end of December, medium quality rice reflected a greater decline than the earlier increase in prices so that the quarter under review closed with a net fall of Rs. 3.60 per maund of Rs. 28.80. However, the corresponding quotation a year ago was still lower at Rs. 27.50.

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