INFLUENCE OF OESTROGEN ADMINISTRATION IN VIVO AND IN VITRO ON THE RELEASE AND SYNTHESIS OF PROLACTIN FROM INCUBATED PITUITARIES

1977 ◽  
Vol 86 (4) ◽  
pp. 714-721 ◽  
Author(s):  
Marta E. Apfelbaum ◽  
S. Taleisnik
Keyword(s):  
Incubation Medium ◽  
Direct Action ◽  
Ovariectomized Rats ◽  
Spontaneous Release ◽  
Prolactin Cells ◽  
Oestradiol Benzoate ◽  
Pre Treatment ◽  
Higher Doses

ABSTRACT The release and synthesis of prolactin were studied in incubated adenohypophyses from ovariectomized rats. After a 4 h incubation period the prolactin concentration in the medium markedly increased whereas that in the gland was reduced. However, the concentration of prolactin in the system, tissue plus medium, after 4 h was almost twice as much as that present at the beginning of incubation indicating spontaneous synthesis. This spontaneous release and synthesis of prolactin was greatly increased in incubated glands from ovariectomized oestrogen-treated rats. Oestradiol benzoate was injected in doses of 2.5, 5.0 or 10.0 μg/rat 2 or 24 h before killing the animals. Lower effects were obtained in glands from 2 h-oestradiol-pre-treated rats than from 24 h-oestradiol-primed rats. Oestradiol-17β (55, 166, 500 and 1500 ng/ml) added to the incubation medium also enhanced the release and synthesis of prolactin and the effect was more marked in glands from oestrogen injected rats than in those of non-treated animals. The increase was dose-related although the higher doses were less effective. These results provide further evidence of the effect of oestrogen on the release and synthesis of prolactin by a direct action on the pituitary gland. They also show that oestradiol pre-treatment in vivo increase the response of the prolactin cells towards oestradiol in vitro.

INFLUENCE OF OESTROGEN ADMINISTRATION IN VIVO AND IN VITRO ON THE RELEASE AND SYNTHESIS OF LH AND FSH FROM INCUBATED PITUITARIES

1977 ◽  
Vol 86 (4) ◽  
pp. 704-713 ◽  
Author(s):  
Marta E. Apfelbaum ◽  
S. Taleisnik
Keyword(s):  
Incubation Medium ◽  
Additive Effects ◽  
Spontaneous Release ◽  
Oestrogen Treatment ◽  
Gonadotrophin Secretion ◽  
Oestradiol Benzoate ◽  
Dose Dependent

ABSTRACT The effect of oestrogen on the release and synthesis of LH and FSH was studied in rat adenohypophyses incubated for a period of 4 h in flasks containing 1 ml Eagle's medium. One hemipituitary was used as the experimental gland and the other half served as a control. The spontaneous release of LH and FSH by glands from ovarectomized rats was not affected by oestradiol-17β added to the incubation medium in doses of 55, 166, 500 and 1500 ng/ml. The amount of hormones released by pituitaries from spayed rats injected with oestradiol benzoate (2.5, 5.0 and 10.0 μg/rat) 2 h or 24 h before killing the animals too was not different from that of oil-injected rats. Neither was there any effect of oestrogen when added to the incubation medium of glands from oestrogen-pre-treated rats. However, the concentration of LH and FSH in the gland increased when oestrogen was added to the incubation medium, indicating enhanced synthesis. The effect was dose-dependent up to the dose of 500 ng/ml oestradiol but a dose of 1500 ng/ml was less effective. Increased synthesis of LH but not of FSH was also observed in incubated glands from rats injected with oestrogen 24 h before death, but no changes were seen in those of rats killed 2 h after treatment. Additive effects occurred with the in vivo and in vitro steroid treatment. These results indicate that oestrogen favours synthesis of LH and FSH in cultured pituitaries, without affecting gonadotrophin secretion and that the changes induced in the in situ gland by oestrogen treatment are reflected by their in vitro activity.

PROGESTERONE TREATMENT INCREASES PITUITARY OESTRADIOL RETENTION IN THE OVARIECTOMIZED NORMAL FEMALE RAT BUT NOT IN THE MALE NOR IN THE ANDROGEN- OR OESTROGEN-STERILIZED FEMALE RAT

1977 ◽  
Vol 84 (2) ◽  
pp. 268-280 ◽  
Author(s):  
Robert D. Lisk ◽  
Lawrence A. Reuter
Keyword(s):  
Testosterone Propionate ◽  
Ovariectomized Rats ◽  
Normal Female ◽  
Nuclear Fraction ◽  
Female Rat ◽  
Treatment Conditions ◽  
Oestradiol Benzoate ◽  
Pre Treatment

ABSTRACT Pituitary retention of [3H]oestradiol in ovariectomized rats was measured following in vivo progesterone pre-treatment and found to be significantly increased after 48, 72, 96 and 120 h of pre-treatment. Increased [3H]oestradiol retention was also observed for at least up to 72 h after removal of the progesterone pre-treatment source. This retention was measured as dpm per mg dry tissue weight. [3H]Oestradiol retention was also measured in the nuclear fraction of tissues incubated with [3H]oestradiol in vitro. Following 72 h of in vivo progesterone pre-treatment, the nuclear fraction from the pituitary was found to retain significantly more [3H]oestradiol than corresponding fractions from non-treated animals. In contrast to ovariectomized females, no increase in [3H]oestradiol retention was found in the pituitary of orchidectomized males pre-treated with progesterone for 72 h. [3H]Oestradiol retention by pituitaries of ovariectomized rats injected on the day of birth with 200 μg oestradiol benzoate (OeB) or 500 μg testosterone propionate (TP) was significantly decreased in comparison to control animals. When the rats were pre-treated in vivo with oestradiol for 6 or 72 h and [3H]oestradiol retention was measured 6 or 24 h after this pre-treatment, the OeB and TP treated animals retained significantly less [3H]oestradiol under most treatment conditions. Progesterone pretreatment for 24 or 72 h in vivo followed by measurement of [3H]oestradiol retention immediately or 6 or 24 h later resulted in a significant increase in [3H]oestradiol retention for the control animals. In contrast, the neonatally OeB or TP treated animals differed significantly by not showing increased retention. When [3H]oestradiol retention of the pituitary was measured in vitro following homogenization at 0°C and incubation at 37°C for 1 h, the nuclear fraction from both OeB and TP treated animals was found to retain less hormone per unit DNA; however, this decrease was significant only for the TP animals. Thus, males and androgen- or oestrogensterilized females have an altered and reduced augmentation of pituitary oestradiol retention in response to both oestrogen and progesterone pretreatments.

IN VITRO UPTAKE OF TRITIATED OESTRADIOL BY THE ANTERIOR HYPOTHALAMUS AND HYPOPHYSIS OF THE RAT

1970 ◽  
Vol 64 (4) ◽  
pp. 687-695 ◽  
Author(s):  
Junzo Kato
Keyword(s):  
Incubation Medium ◽  
Posterior Hypothalamus ◽  
Anterior Hypothalamus ◽  
Ovariectomized Rats ◽  
Free Medium ◽  
Cortex Cerebri ◽  
Anterior Hypophysis ◽  
In Vitro Uptake

ABSTRACT The anterior, middle, and posterior hypothalamus, the cortex cerebri, the anterior hypophysis as well as the diaphragm of adult ovariectomized rats were incubated in vitro with tritiated 17β-oestradiol. The uptake of tritiated oestradiol was differentially distributed intracerebrally with higher accumulation in the anterior hypothalamus and the hypophysis. Lowering the temperature of the incubation medium caused a reduction in the uptake of radioactivity by the anterior hypothalamus as compared to that found in other brain tissues. Tritiated oestradiol taken up in vitro by the anterior hypothalamus and the hypophysis tended to be retained after further incubation in a steroid-free medium. The addition of non-radioactive 17β-oestradiol to the medium inhibited the uptake of tritiated oestradiol by these tissues. Moreover, pretreatment with non-radioactive 17β-oestradiol in vivo prevented the preferential accumulation of tritiated oestradiol in vitro in the anterior hypothalamus and the hypophysis. These results indicate that oestradiol is preferentially taken up in vitro by the anterior hypothalamus and the hypophysis of the rat.

INTERACTION BETWEEN OESTROGEN AND GONADOTROPHIN-RELEASING HORMONE ON THE RELEASE AND SYNTHESIS OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE FROM INCUBATED PITUITARIES

1976 ◽  
Vol 68 (1) ◽  
pp. 127-136 ◽  
Author(s):  
MARTA E. APFELBAUM ◽  
S. TALEISNIK
Keyword(s):  
Incubation Medium ◽  
Ovariectomized Rats ◽  
Spontaneous Release ◽  
Dose Response Relationship ◽  
Dual Effect ◽  
Releasing Hormone ◽  
Oestradiol Benzoate ◽  
Pituitary Glands ◽  
Gonadotrophin Releasing Hormone ◽  
Gland Content

SUMMARY The release and synthesis of LH and FSH were studied in adenohypophyses from ovariectomized rats incubated for a period of 4 h in flasks containing 1 ml Eagle's medium. One hemipituitary was used as the experimental gland and the other half served as a control. Glands from ovariectomized untreated animals showed a spontaneous release of LH and FSH and the amount of hormones released (per mg gland) by both the hemipituitaries was not significantly different. Also the content of the hormones at the end of the incubation period was similar in both halves. Gonadotrophin-releasing hormone (Gn-RH) added to the incubation medium stimulated the release of LH and FSH. A dose–response relationship was obtained between doses of 0·51 and 8·00 ng/ml medium. Although lower doses were required to increase the release of LH, the amount of FSH released was higher when expressed as a percentage of gland content. Pituitary glands from ovariectomized rats treated with 5 μg oestradiol benzoate 24 h before being killed showed an increase in sensitivity to Gn-RH, but the response decreased when oestrogen was injected 2 h before death. Also the addition of oestradiol-17β to the incubation medium inhibited LH and FSH release induced by Gn-RH. Gonadotrophin-releasing hormone increased the spontaneous synthesis of LH and FSH observed in the incubated pituitaries. This effect of Gn-RH was stimulated by the injection of oestrogen into the donor animals whereas administration of oestrogen into the medium enhanced the synthesis of LH and partially inhibited that of FSH. These results provide evidence for a dual effect of oestrogen on the release of LH and FSH induced by Gn-RH. They also show that synthesis of gonadotrophic hormones was favoured by oestrogen or by increased gonadotrophin release.

Release of LH in vitro from anterior pituitary glands of ovariectomized rats by LRH or elevated potassium concentration after pre-treatment with oestradiol benzoate in vivo

1982 ◽  
Vol 99 (2) ◽  
pp. 206-210 ◽  
Author(s):  
A. M. I. Tijssen ◽  
J. de Koning ◽  
G. P. van Rees
Keyword(s):  
Ovariectomized Rats ◽  
Bicarbonate Buffer ◽  
High K ◽  
Oestradiol Benzoate ◽  
Negative Effect ◽  
Pituitary Glands ◽  
Lh Release ◽  
Pre Treatment ◽  
Positive Effect

Abstract. Pituitary glands from ovariectomized rats which had been pre-treated with oestradiol benzoate (OeB) or solvent oil were incubated in Krebs-Ringer bicarbonate buffer with glucose containing either LRH (1000 ng/ml) or a high K+ concentration (50 mM). OeB (7 μg sc) or oil was injected at 2.5 or 6.5 h before the beginning of the incubation experiment or during the three preceding days (three daily injections). Depending upon the period during which the pituitary glands had been exposed to OeB LH release induced by LRH was inhibited (negative effect of OeB) or augmented (positive effect). When the glands were incubated in medium containing high K+, only the negative effect of OeB pre-treatment was seen. It is concluded that that part of LRH-induced LH release which is mimicked by high K+ is involved in the negative effect of OeB, but not in its positive effect.

Effect of hormone pre-treatment of prepubertal sheep on the production and developmental capacity of oocytes in vitro and in vivo

1997 ◽  
Vol 9 (6) ◽  
pp. 625 ◽  
Author(s):  
J. K. O'Brien ◽  
N. F. G. Beck ◽  
W. M. C. Maxwell ◽  
G. Evans
Keyword(s):  
In Vitro Maturation ◽  
Single Treatment ◽  
Oocyte Collection ◽  
Oestradiol Benzoate ◽  
Developmental Capacity ◽  
Pre Treatment ◽  
Pregnant Mare Serum Gonadotrophin

Twenty 36-week-old Merino lambs were given either 3, 1 or 0 treatments of 50 µg oestradiol benzoate and (48 h later) a 1·5 mg Norgestamet implant left in situ for 9 days (3-, 1- and 0CYCLE+G). On Day 7 after the last implant insertion, and on the same day for 0CYCLE+G, each lamb received 400 I.U. pregnant mare serum gonadotrophin and 6 mg follicle-stimulating hormone (FSH). The reproductive tracts were removed for oocyte collection 24 h after FSH. Reproductive tracts were also collected from 16-24-week-old lambs (n = 31) (0CYCLEG). The number of antral follicles per ovary was similar for the 3-, 1- and 0CYCLE+G treatments. Similar rates of in vitro maturation and monospermic fertilization were obtained for all groups. The proportion of blastocysts per cleaved oocyte was higher for 1CYCLE+G (50·5%) than for 3CYCLE+G (32·9%), 0CYCLE+G (24·3%), and 0CYCLEG (11·8%) (P < 0·05). Viable fetuses were obtained at Day 93 of pregnancy after transfer of embryos from all treatments. These results indicate that a single treatment with oestrogen and progesterone, prior to gonadotrophin stimulation, will increase the yield and developmental capacity of oocytes from prepubertal sheep.

In vitro and in vivo TSH releasing activity of two new analogues of TRH

1987 ◽  
Vol 114 (2) ◽  
pp. 314-320 ◽  
Author(s):  
Jean-Paul Roussel ◽  
Lucia Tapia-Arancibia ◽  
Hélène Astier ◽  
Wolfgang Klingler
Keyword(s):  
Body Weight ◽  
Biological Activity ◽  
Spontaneous Release ◽  
Response Curves ◽  
Adult Rats ◽  
Structural Modifications ◽  
Before And After ◽  
Pre Treatment

Abstract. The TSH releasing activity of two new analogues of TRH 'Pyr-(N3-Im-methyl)-His-Pro-NH-(n-amyl)' (I) and 'Pyr-His-Pro-(tyramine)' (II) was tested and compared with that of TRH in adult rats to test how structural modifications in the TRH molecule affect its biological activity: 1) in vitro in superfused pituitaries and 2) in vivo after ip injection, with measurement of TSH by RIA before and after addition of each secretagogue. Analogue I was found to be more potent than both TRH itself and Analogue II in stimulating TSH release: at 10 nmol/l in vitro, the ratio of induced to spontaneous release was 4.13 ± 0.35, 2.98 ± 0.20, and 1.19 ± 0.17, respectively for each secretagogue, with a 50% effective dose of 6 × 10−9 mol/l for Analogue I and 5 × 10−8 mol/l for TRH. A similar order of potency in increasing plasma TSH (Analogue I > TRH > Analogue II) was found in vivo, as shown by dose-response curves. After a 4-day pre-treatment with TRH (2 × 100 μg/day) a similar TSH response to TRH and Analogue I (500 nmol/kg body weight) was observed. By contrast, the dose of Analogue II needed to obtain the same stimulatory effect on TSH release was twice as high. The biological activity of TRH appears to be more effectively increased by replacing an H atom by an amyl group in the C-terminal amide function of the proline residue of TRH than by a tyramyl group in the same residue.

INFLUENCE OF CHLOROPHENOXYISOBUTYRATE (CPIB) ON THYROID PARAMETERS

1969 ◽  
Vol 60 (2) ◽  
pp. 294-302 ◽  
Author(s):  
J. Mølholm Hansen
Keyword(s):  
Free Thyroxine ◽  
Term Therapy ◽  
Low Doses ◽  
Testosterone Metabolism ◽  
Pre Treatment ◽  
Long Term Therapy ◽  
Higher Doses

ABSTRACT Chlorophenoxyisobutyrate (CPIB) added to serum in vitro increases the quantity of dialysable thyroxine. The same effect can be obtained in vivo following large doses of the preparation. After low doses, increase in serum proteinbound iodine (PBI) is observed and with higher doses this increase is not observed, probably because of the thyroxine-displacing effect. Free thyroxine increases in practically all patients investigated. In long-term treated patients the alterations in dialysable thyroxine, serum proteinbound iodine and free thyroxine are transient; pre-treatment values being regained in the course of ½–4 months. 131I uptake in the thyroid gland is influenced irregularly and transiently possibly via inhibition of the thyrotrophin production in the hypophysis. The effect of CPIB on serum cholesterol appears, in long-term therapy, to be completely independent of the effect on these thyroid parameters. This observation is also supported by the fact that the 14C-testosterone metabolism is normal in patients receiving long-term therapy.

MODIFICATION OF RAT UTERINE MONOAMINE OXIDASE ACTIVITY BY STEROID HORMONES

1975 ◽  
Vol 65 (2) ◽  
pp. 207-214 ◽  
Author(s):  
D. S. GROSSO ◽  
A. M. GAWIENOWSKI
Keyword(s):  
Enzyme Activity ◽  
Monoamine Oxidase ◽  
Direct Action ◽  
Ovariectomized Rats ◽  
Mitochondrial Enzyme ◽  
Rat Uterus ◽  
Mao Activity ◽  
High Concentrations

SUMMARY The monoamine oxidase (MAO) activity in the ovariectomized rat uterus was significantly increased above control levels in animals given testosterone: 33% (P < 0·01) with tryptamine or 34% (P < 0·05) with tyramine as substrate. Activity was also higher in hydrocortisone-treated animals: 30% (P < 0·05) with tyramine or 25% (P < 0·05) with tryptamine as substrate. Progesterone injection increased MAO activity toward tyramine by 20% but towards tryptamine by only 8%. The differences are not statistically significant but are believed to be real since they were reproducible. MAO activity in oestradiol-treated animals was 11% less than in the controls for both substrates. Although they are not significant differences, they were reproducible. No change in MAO activity was observed in the cerebellum, hypothalamus or anterior pituitary of ovariectomized rats after steroid treatment. At oestrus the enzyme activity in the uterus was lower than at dioestrus or prooestrus when β-phenylethylamine was the substrate. When 5-hydroxytryptamine was used to measure enzyme activity, the same values were found at oestrus, dioestrus and prooestrus. Ovariectomy did not cause any changes in MAO activity in any of the tissues. Effects of the steroids in vivo were probably not due to a direct action on the enzyme since only at high concentrations did they have any effect on the mitochondrial enzyme activity of the uterus in vitro.

Effect of 2-substituted oestrogens in vivo on the metabolism of noradrenaline in rat brain

1982 ◽  
Vol 99 (1) ◽  
pp. 1-8 ◽  
Author(s):  
G. Köster ◽  
H. Breuer ◽  
H. Th. Schneider
Keyword(s):  
Brain Regions ◽  
Inhibitory Effect ◽  
Ovariectomized Rats ◽  
Experimental Conditions ◽  
Metabolic Pattern ◽  
Metabolism Of Noradrenaline ◽  
Pre Treatment ◽  
Lh Secretion

Abstract. The effects of oestradiol-17β, 2-hydroxyoestradiol-17β and 2-methoxyoestradiol-17β on the metabolism of [3H]noradrenaline were studied in various brain regions of ovariectomized rats in vivo. Under the experimental conditions chosen, oestradiol-17β had no effect on the metabolic pattern of noradrenaline. After pre-treatment of ovariectomized rats with 2-hydroxyoestradiol-17β, the formation of methylated metabolites of noradrenaline (normetanephrine and 3-methoxy-4-hydroxyphenylglycol sulphate) was reduced, whereas that of non-methylated products (3,4-dihydroxymandelic acid and 3,4-dihydroxyphenylglycol sulphate) was increased. The inhibition of methylation was most pronounced in posterior hypothalamus and less significant in anterior hypothalamus and thalamus. Pre-treatment with 2-methoxyoestradiol-17β yielded inconsistent results. From the findings described here it may be concluded that 2-hydroxyoestradiol-17β, as previously shown in vitro, also affects the metabolism of noradrenaline in vivo by directly interacting with the catechol-O-methyltransferase. It is suggested that this metabolic effect may be responsible - at least to some extent - for the inhibitory effect of 2-hydroxyoestradiol-17β on LH secretion.

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