Inhibitory and augmentative effects of oestradiol on LH-RH-induced release of LH by anterior pituitary glands from intact female rats in vitro

1976 ◽  
Vol 5 (5) ◽  
pp. 321-330 ◽  
Author(s):  
J. De Koning ◽  
J.A.M.J. Van Dieten ◽  
G.P. Van Rees
Keyword(s):  
Anterior Pituitary ◽  
Female Rats ◽  
Intact Female ◽  
Pituitary Glands ◽  
Lh Rh

Autonomous FSH synthesis in vitro in anterior pituitary glands and grafts from female rats

1991 ◽  
Vol 129 (1) ◽  
pp. 27-33 ◽  
Author(s):  
J. A. M. J. van Dieten ◽  
J. de Koning ◽  
G. P. van Rees
Keyword(s):  
Follicular Fluid ◽  
Anterior Pituitary ◽  
Female Rats ◽  
Regulatory Mechanisms ◽  
Ovariectomized Rats ◽  
Intact Female ◽  
Pituitary Glands

ABSTRACT When pituitary glands from intact female, but not from ovariectomized rats, are incubated for 8 h in medium TC199 without further additives, FSH is synthesized. This LHRH-independent (or autonomous) FSH synthesis is prevented when bovine follicular fluid (bFF) is added to the incubation medium. Results from preliminary experiments, however, indicate no clear autonomous FSH synthesis after long-term absence of LHRH. To investigate the regulatory mechanisms involved in autonomous FSH synthesis and release, pituitary glands (exposed to endogenous LHRH) and pituitary grafts (not exposed to endogenous LHRH) from intact and ovariectomized rats were incubated for 8 h in medium TC199. Total FSH content (FSH released plus FSH remaining in the tissue) was compared with that in non-incubated glands or grafts, giving an indication of FSH synthesis. In addition, some of the animals were given LHRH pulses for 40 h before incubation. When pituitary tissue was taken from intact female rats, FSH synthesis occurred in the animals' own glands and in grafts from LHRH-pretreated rats. No FSH synthesis was seen in ovariectomized rats with or without pretreatment with bFF and/or LHRH. However, when ovariectomized rats had been pretreated with oestrogen, FSH synthesis was measured in vitro after pulsatile LHRH treatment in vivo. The results indicate that autonomous FSH synthesis in vitro is dependent upon previous (in vivo) exposure of the glands to both oestrogen and LHRH. Journal of Endocrinology (1991) 129, 27–33

REGULATION OF THE METABOLISM OF PITUITARY NUCLEIC ACIDS IN FEMALE RATS

1980 ◽  
Vol 85 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. BÍRÓ
Keyword(s):  
Nucleic Acids ◽  
Intraperitoneal Injection ◽  
Anterior Pituitary ◽  
Rna Metabolism ◽  
Female Rats ◽  
Biphasic Effect ◽  
Lh Rh ◽  
Lh Releasing Hormone

SUMMARY Ovariectomy caused an increase in the metabolism of pituitary nucleic acids. This effect was reversed in vivo by a biphasic action of oestradiol-17β which first facilitated RNA metabolism after 8 h and then inhibited it 16 h after intraperitoneal injection. To analyse the origin of this biphasic effect the roles of LH releasing hormone (LH-RH) and hysterectomy were examined. Incorporation of uridine into the RNA of the anterior pituitary gland of female rats was inhibited both in vivo and in vitro by LH-RH. Hysterectomy augmented the increase in the RNA metabolism caused by ovariectomy whereas steroid-free uterine extracts inhibited the increase significantly. We have concluded that extrapituitary factors may be involved in the effects of oestrogen on the metabolism of pituitary nucleic acids.

Effect of inhibin-like activity on LH-RH-stimulated release of FSH by pituitary glands from female rats in vitro

Life Sciences ◽  
1983 ◽  
Vol 32 (10) ◽  
pp. 1091-1098 ◽  
Author(s):  
A.A.J. Jenner ◽  
J. de Koning ◽  
G.P. van Rees
Keyword(s):  
Female Rats ◽  
Pituitary Glands ◽  
Lh Rh

INFLUENCE OF STEROID SEX HORMONES ON THE F. S. H.-RELEASE BY RAT HYPOPHYSES IN VITRO

1961 ◽  
Vol 36 (4) ◽  
pp. 485-497 ◽  
Author(s):  
G. P. van Rees
Keyword(s):  
Sex Hormones ◽  
Female Rats ◽  
Male Rats ◽  
Intact Female ◽  
Intact Male ◽  
Incubation Experiments ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Steroid Sex Hormones

ABSTRACT The hypothesis that steroid sex hormones influence pituitary F. S. H. by independent actions on its production and capacity of the gland to release it has been investigated by means of incubation experiments. During incubation, rat pituitary glands released considerable amounts of F. S. H. into the medium. Inactivation of F. S. H. during incubation could not be demonstrated; once (in females) some production of F. S. H. was even observed. The amount of F. S. H. which is released into the medium is influenced by the quantity of F. S. H. stored in the hypophyses. Hypophyses from male rats pretreated with oestradiol released relatively more F. S. H. into the medium than hypophyses from control animals. On the other hand, pretreatment with testosterone caused the pituitary glands to release less F. S. H. into the medium. In agreement with these results, hypophyses from intact male rats released relatively less F. S. H. than hypophyses from intact female rats. These facts support the hypothesis that androgens depress pituitary F. S. H.-secretion by inhibiting the capacity to release it, while oestrogens, which can even promote this property of the pituitary gland, also act by directly inhibiting its production.

scholarly journals Comparison between the effects of LH-RH and raised K+ concentration on release of LH from pituitary glands of female rats in vitro

FEBS Letters ◽  
1981 ◽  
Vol 126 (2) ◽  
pp. 199-202 ◽  
Author(s):  
J. De Koning ◽  
A.M.I. Tijssen ◽  
J.A.M.J. Van Dieten ◽  
G.P. Van Rees
Keyword(s):  
Female Rats ◽  
Pituitary Glands ◽  
K Concentration ◽  
Lh Rh

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.

STUDIES ON A PROTEIN SYNTHESIS DEPENDENT STEP IN LH RELEASE BY LH-RH

1979 ◽  
Vol 92 (4) ◽  
pp. 648-657 ◽  
Author(s):  
J. de Koning ◽  
J. A. M. J. van Dieten ◽  
A. M. I. Tijssen ◽  
G. P. van Rees
Keyword(s):  
Protein Synthesis ◽  
Female Rats ◽  
Protein Factor ◽  
Active Concentration ◽  
Long Time ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh ◽  
Inhibitor Of Protein Synthesis

ABSTRACT The hypothesis that LH-RH induces LH release partly through a protein synthesis dependent step (protein factor) was further investigated using two different experimental designs. First, during incubation of pituitary glands of intact dioestrous female rats with a maximally active concentration of LH-RH, the inhibitor of protein synthesis cycloheximide was added at various times after the beginning of the incubation. The results show that it takes a relatively long time, i.e. more than 1 h of exposure to LH-RH before the amount of the protein factor has increased sufficiently to allow a maximal LH secretion. Secondly, LH-RH was injected iv after which the protein factor was assayed by incubating the pituitary glands with a maximally active concentration of LH-RH in the presence of cycloheximide and measuring LH release in vitro. It was found that 1 h after the injection sufficient protein factor was present to permit an elevated response to LH-RH. This response could be suppressed by injecting cycloheximide prior to LH-RH. When the interval between injection of LH-RH and beginning of the incubation was increased to 2 h, LH release in vitro decreased again. However, ovariectomy immediately before LH-RH injection resulted in maintenance of the elevated response to LH-RH in vitro, indicating a role of the ovaries in this phenomenon.

Time course of inhibition of synthesis and basal release of FSH from pituitary glands of female rats by bovine follicular fluid in vitro

1982 ◽  
Vol 101 (4) ◽  
pp. 501-506 ◽  
Author(s):  
A. A. J. Jenner ◽  
J. de Koning ◽  
G. P. van Rees
Keyword(s):  
Follicular Fluid ◽  
Time Course ◽  
Mechanisms Of Action ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Intact Female ◽  
In Vitro Technique ◽  
Basal Release ◽  
Pituitary Glands

Abstract. Inhibin-like activity in steroid-free bovine follicular fluid (bFF) is demonstrated using an in vitro technique with hemi-pituitary glands from intact female (second day of dioestrus) and ovariectomized rats: synthesis as well as basal release of FSH, but not of LH, are inhibited profoundly. The results confirm and extend data from other investigators on the action of inhibin-like material. The effect of the inhibin-like activity is shown to be reversible, as synthesis and the rise of basal release are restored when bFF is withdrawn from the incubation medium. Synthesis of FSH seems to be inhibited earlier than basal release, and it is suggested that the inhibin-like material acts only directly on FSH synthesis. Some possibilities of the mechanisms of action of inhibin-like activity are discussed.

scholarly journals In vitro effect of leptin on LH release by anterior pituitary glands from female rats at the time of spontaneous and steroid-induced LH surge

2001 ◽  
pp. 659-665 ◽  
Author(s):  
SN De Biasi ◽  
LI Apfelbaum ◽  
ME Apfelbaum
Keyword(s):  
Estrous Cycle ◽  
Anterior Pituitary ◽  
Female Rats ◽  
Female Rat ◽  
Lh Surge ◽  
Pituitary Glands ◽  
Lh Release ◽  
Vitro Effect ◽  
Stimulation Of

OBJECTIVE: The purpose of this work was to study the direct effect of leptin on LH release by anterior pituitary glands from female rats at the time of spontaneous and steroid-induced LH surge. METHODS: LH responsiveness to leptin by pituitaries from rats killed in the afternoon (1500 h) at different stages of the 4-day estrous cycle (diestrus-1: D1; diestrus-2: D2; proestrus; estrus), ovariectomized (OVX; 15 days post-castration) and ovariectomized steroid-primed (OVX-E(2)/Pg; pretreated with 5 microg estradiol and 1 mg progesterone), was evaluated in vitro. Hemi-adenohypophyses were incubated in the presence of synthetic murine leptin for 3 h. RESULTS: Addition of increasing concentrations of leptin (0.1-100 nmol/l) to the incubation medium of proestrus pituitaries produced a dose-related stimulation of LH release; the maximal increase to 315% of control was obtained with 10 nmol/l leptin. Leptin (10 nmol/l) enhanced LH release at all days of the estrous cycle, the greatest response occurring in proestrus (318%) and the lowest at D1 (123%). In order to evaluate the role of nitric oxide (NO) in the action of leptin on LH release, glands from proestrus rats were incubated in the presence of 10 nmol/l leptin with or without 0.3 mmol/l N(G)-monomethyl-l-arginine (NMMA), a competitive inhibitor of NO synthase (NOS). NMMA completely suppressed the stimulation of LH release induced by leptin. Leptin also stimulated LH release by pituitaries from OVX rats, and treatment with steroid hormones led to a marked increase in the response (OVX: 162% compared with OVX-E(2)/Pg: 263%; P<0.05). For comparative analysis, a similar experimental procedure was carried out using GnRH (10 nmol/l). Leptin acts at the pituitary level in a similar manner as GnRH, although with significantly lower potency. CONCLUSIONS: These results confirm and extend previous reports regarding a direct action of leptin at the pituitary level, stimulating LH release by anterior pituitaries from female rats at the time of spontaneous and steroid-induced LH surge. In the female rat pituitary this leptin action is controlled by gonadal steroids and mediated by NO.

Size heterogeneity of prolactin secreted from and stored in the rat anterior pituitary gland in vitro

1984 ◽  
Vol 4 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Andrew M. Bentley ◽  
Teresa K. Surowy ◽  
Michael Wallis
Keyword(s):  
Anterior Pituitary ◽  
Relative Proportion ◽  
Gel Filtration ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Pituitary Glands ◽  
Dimeric Form ◽  
Size Heterogeneity ◽  
Pituitary Prolactin

The size heterogeneity of rat pituitary prolactin was investigated using anterior pituitary glands from female rats incubated in vitro and gel filtration on Sephadex G-100. Monomeric prolactin was preferentially secreted compared with dimeric and ‘trimeric” material. When glands were incubated with dopamine, prolactin secretion was inhibited and the relative proportion of dimer in the gland (but not the medium) was decreased. Morphine sulphate reversed the effect of dopamine on prolactin secretion and on the proportion of prolactin in the gland that was in the dimeric form. The results suggest that monomeric prolactin is more readily secreted than dimer, and that dopamine decreases the production or stability of the dimer.

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