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.

Effect of Ca2+ deprivation on release of luteinizing hormone induced by luteinizing hormone releasing hormone from female rat pituitary glands in vitro

1982 ◽  
Vol 94 (1) ◽  
pp. 11-20 ◽  
Author(s):  
J. de Koning ◽  
A. M. I. Tijssen ◽  
J. A. M. J. van Dieten ◽  
G. P. van Rees
Keyword(s):  
Protein Synthesis ◽  
Initial Phase ◽  
Phase Response ◽  
Ovariectomized Rats ◽  
Second Phase ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh ◽  
Intact Rats

Continuous exposure of hemi-pituitary glands from intact female rats to LH releasing hormone (LH-RH) in vitro displayed three phases in the pattern of LH release: during the first hour release of LH was low (first phase response), then it increased to a higher level during the second hour and remained constant during the next 2 h (second phase response), after which there was a refractoriness of LH release (third phase response). The initial phase response of pituitary glands from intact rats was blocked by EGTA (a Ca2+ chelator) but there was a small but significant increase in the rate of LH release during the second phase response. This increase could be prevented by inhibition of protein synthesis by cycloheximide. Cycloheximide and EGTA did not affect basal release of LH by glands from intact rats, neither did EGTA affect the high basal release of LH by glands from ovariectomized rats. However, the LH-RH-induced release of LH from pituitary glands of ovariectomized rats, which did not show the initial phase of low LH release, was completely suppressed by EGTA throughout a 4-h incubation period. The pattern of LH release stimulated by the combination of N6-monobutyryl cyclic AMP and theophylline (mbcAMP/theophylline) showed an initial phase of low LH release lasting 4 h after which it increased. The magnitude of the effect was small compared with the action of LH-RH. As it did with LH-RH, EGTA completely blocked the initial response, but allowed a small increase in the rate of LH release thereafter; this increase could also be blocked by inhibition of protein synthesis. Addition of EGTA to media during pretreatment of pituitary glands from intact rats with either LH-RH or mbcAMP/theophylline did not impair the facilitatory effect of these secretagogues on the responsiveness of the glands to subsequent exposure to LH-RH and cycloheximide and normal Ca2+ levels. The restoration of Ca2+ levels after withdrawal neither affected basal nor LH-RH-induced release of LH. Exclusion of Ca2+ from the media during a 6-h incubation of pituitary glands from intact rats with LH-RH prevented the glands from becoming refractory to subsequent stimulation by LH-RH, which occurs when normal Ca2+ concentrations are present. The results suggested that extracellular Ca2+ is obligatory for LH release and the induction of refractoriness by LH-RH. In contrast, that part of the action of LH-RH which is cyclic AMP-mediated and protein synthesis-dependent is not affected by withdrawal of extracellular Ca2+.

DEPENDENCE ON PROTEIN SYNTHESIS OF THE N6-MONOBUTYRYL CYCLIC AMP PLUS THEOPHYLLINE MEDIATED RELEASE OF LUTEINIZING HORMONE INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE FROM RAT PITUITARY GLANDS IN VITRO

1981 ◽  
Vol 88 (3) ◽  
pp. 329-338 ◽  
Author(s):  
J. DE KONING ◽  
J. A. M. J. VAN DIETEN ◽  
A. M. I. TIJSSEN ◽  
G. P. VAN REES
Keyword(s):  
Protein Synthesis ◽  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Female Rats ◽  
Releasing Hormone ◽  
Pituitary Tissue ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh ◽  
Lh Releasing Hormone

The involvement of cyclic AMP in the action of LH releasing hormone (LH-RH) on LH secretion was studied by incubating pituitary glands from adult female rats on day 2 of dioestrus with 1 mm-N6-monobutyryl cyclic AMP (mbcAMP) and 10 mm-theophylline for periods of up to 10 h. This treatment induced a pattern of LH release similar to that observed in the presence of a low concentration of LH-RH (0·1 ng LH-RH/ml), i.e. an initial 4 h period during which the release of LH was minimal was followed subsequently by an increased rate of release. In this system inhibition of protein synthesis by cycloheximide (25 μg/ml) did not impair the initial response of the pituitary tissue but the increase in the rate of LH release during the second phase of the response was blocked. Preincubation with mbcAMP and theophylline increased the responsiveness of the pituitary tissue to LH-RH. This action could be prevented by including cycloheximide during the preincubation period, whereas addition of this drug during the incubation with LH-RH no longer impaired the increased responsiveness. The size of the sensitizing action of mbcAMP and theophylline mediated through the induction of protein synthesis was comparable with that of a high concentration of LH-RH. From the absence of a significant change in total LH during the preincubation period, it was concluded that the increased responsiveness was not the result of newly synthesized LH. The present results suggest a role or roles for cyclic AMP in the secretion of LH induced by LH-RH. Besides an effect on the formation of a factor related to the synthesis of protein, other than LH which has a permissive role in the acute release of LH, cyclic AMP might also be concerned in the secretion process through a pathway which does not involve synthesis of protein.

Comparison between the biological effects of LH-RH and buserelin on the induction of LH release from hemi-pituitary glands of female rats in vitro

Life Sciences ◽  
1984 ◽  
Vol 34 (20) ◽  
pp. 1937-1943 ◽  
Author(s):  
J. de Koning ◽  
A.M.I. Tijssen ◽  
T.R. Koiter ◽  
G.A. Schuiling ◽  
G.P. van Rees
Keyword(s):  
Biological Effects ◽  
Female Rats ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh

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

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

Wen-Jing-Tang, a Traditional Chinese Herbal Medicine Increases Luteinizing Hormone Release In Vitro

1986 ◽  
Vol 14 (03n04) ◽  
pp. 157-160 ◽  
Author(s):  
Akira Miyake ◽  
Jin-Woo Lee ◽  
Keiichi Tasaka ◽  
Shirou Ohtsuka ◽  
Toshihiro Aono
Keyword(s):  
Herbal Medicine ◽  
Luteinizing Hormone ◽  
Chinese Herbal Medicine ◽  
Female Rats ◽  
Normal Female ◽  
Traditional Chinese Herbal Medicine ◽  
Chinese Herbal ◽  
Lh Release ◽  
Lh Rh

For examination of the effect on luteinizing hormone (LH) release of Wen-Jing-Tang, a traditional Chinese herbal medicine, the pituitary from normal female rats in diestrus was perifused alone or in sequence with the mediobasal hypothalamus (MBH) in a sequential double-chamber perifusion system. Wen-Jing-Tang at 5 or 500 μg/ml induced significant LH release (60-95 % increase) from the pituitary in series with the MBH, but had no effect on LH release from the pituitary perifused alone. These data suggest that Wen-Jing-Tang induces LH release from the pituitary through hypothalamic LH-RH.

LH-RH-dependent synthesis of protein necessary for LH release from rat pituitary glands in vitro

1976 ◽  
Vol 5 (1-2) ◽  
pp. 151-160 ◽  
Author(s):  
J. De Koning ◽  
J.A.M.J. Van Dieten ◽  
G.P. Van Rees
Keyword(s):  
Rat Pituitary ◽  
Pituitary Glands ◽  
Lh Release ◽  
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.

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