Heterogeneity of rat FSH by chromatofocusing: studies on serum FSH, hormone released in vitro and metabolic clearance rates of its various forms [ill]

1985 ◽  
Vol 105 (1) ◽  
pp. 29-37 ◽  
Author(s):  
W. F. P. Blum ◽  
D. Gupta
Keyword(s):  
Molecular Size ◽  
Male Rats ◽  
Metabolic Clearance ◽  
Clearance Rates ◽  
Charged Species ◽  
Rat Pituitary ◽  
Isoelectric Points ◽  
Exclusion Chromatography ◽  
Pituitary Glands

ABSTRACT Rat pituitary FSH was fractionated by chromatofocusing between pH 6 and 3. Ten components were resolved having apparent isoelectric points between 3·1 and 5·1. A comparative study of pituitary FSH and FSH secreted in vitro by quartered pituitary glands in the presence and in the absence of gonadotrophin-releasing hormone (GnRH) revealed similar patterns of charged species of intracellular and released FSH. Although GnRH increased FSH secretion about fourfold, no influence on the pattern of charged species was observed. Utilizing exclusion chromatography and chromatofocusing, pituitary FSH was compared to serum FSH which had been extracted by immunoaffinity chromatography. The results demonstrate for serum FSH a larger molecular size and a relative shift to more acidic components. Metabolic clearance rates of eight FSH components separated by chromato-focusing were measured in adult male rats. Half-lives varied between 13 min and several hours. A correlation existed between decrease of isoelectric points and decrease of metabolic clearance rates. These findings suggest that (1) all hypophysial FSH components are secreted into the circulation at similar rates and (2) the more acidic FSH components which appear to contain increased sialic acid, have a longer circulatory half-life and are more abundant in serum. It is concluded that sialylation may be involved in modulating serum FSH levels. J. Endocr. (1985) 105, 29–37

BIOSYNTHESIS OF GONADOTROPHINS BY RAT PITUITARIES IN VITRO

1975 ◽  
Vol 66 (3) ◽  
pp. 369-374 ◽  
Author(s):  
MRIDULA CHOWDHURY ◽  
EMIL STEINBERGER
Keyword(s):  
Comparative Study ◽  
Anterior Pituitary ◽  
Male Rats ◽  
Leucine Incorporation ◽  
Experimental Conditions ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Endogenous Proteases ◽  
Pituitary Homogenate

SUMMARY A method has been developed for studying biosynthesis of FSH in the rat pituitary in vitro. Anterior pituitary glands were incubated with [3H]leucine; a specific and sensitive immunoprecipitation technique was used to isolate FSH from the pituitary homogenate. Total FSH content of the samples was measured by a double-antibody radioimmunoassay technique. Using this technique, a comparative study of LH and FSH synthesis in the same pituitary of adult male rats incubated for various intervals (0·5–6 h) was done. Increased incorporation of [3H]leucine into both LH and FSH with time was noted. The rate and amount of [3H]leucine incorporation into FSH was found to be higher than that into LH, indicating that either the rate of FSH synthesis is higher than that of LH or FSH has more leucine residues than LH. Greater susceptibility of LH to degradation by endogenous proteases during dialysis may also reflect less incorporation of [3H]leucine into LH. This method provides a reliable tool for evaluating FSH synthesis under various experimental conditions.

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.

IMMATURE RAT PITUITARY GLANDS IN VITRO: AGE- AND SEX-RELATED CHANGES IN LUTEINIZING HORMONE RELEASING HORMONE-STIMULATED GONADOTROPHIN RELEASE

1977 ◽  
Vol 73 (2) ◽  
pp. 309-319 ◽  
Author(s):  
J. DULLAART
Keyword(s):  
Male Rats ◽  
Steady Increase ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Lh Release ◽  
The One ◽  
Lh Rh ◽  
Lh Releasing Hormone

SUMMARY Pituitary glands from immature female and male rats aged between 5 and 30 days were incubated in vitro and the effect of LH releasing hormone (RH) on the release of LH and FSH was studied. Pituitary gonadotrophin contents were also measured. Gonadotrophin release showed changes with age as well as sex differences: after LH-RH stimulation the female pattern of release of LH and FSH (expressed per mg pituitary tissue) showed a peak at day 15; the male pattern of LH release was characterized by a steady increase with age, whereas FSH release stayed more or less constant from day 10 onwards. In both sexes the LH:FSH ratio increased with age, both in pituitary gonadotrophin content and in the mixture of gonadotrophins released. It is discussed, that the prepubertal development of pituitary gonadotrophic function might be determined on the one hand by rather autonomous growth processes (more or less similar in female and male hypophyses) and on the other hand by modulating influences of sex steroid hormones, which are different in female and male animals.

Postreceptorial refractoriness of prolactin release mechanisms

1983 ◽  
Vol 61 (7) ◽  
pp. 676-684 ◽  
Author(s):  
R. Collu ◽  
J. R. Ducharme ◽  
D. Eljarmak ◽  
A. M. Marchisio ◽  
J. Bertrand ◽  
...  
Keyword(s):  
Binding Sites ◽  
Immobilization Stress ◽  
Significant Rise ◽  
Male Rats ◽  
Plasma Prolactin ◽  
Initial Value ◽  
Prolactin Release ◽  
Pituitary Glands ◽  
Plasma Prl

Whilc a first injection of the antidopaminergic benzamide drug, sulpiride, induced a large rise in plasma prolactin (PRL) levels in chronically cannulated adult male rats, a second injection given 2 h later was totally inactive although the pituitary content of the hormone was still 76% of the initial value. When the second injection was given 8 h after the first it was slightly effective, but when administered 24 h later it was as effective as the first. The second of two consecutive injections of haloperidol given at 2-h intervals, or an injection of morphine given 2 h after sulpiride, were incapable of inducing a release of PRL. Two hours after an injection of sulpiride, a 30-min period of immobilization stress induced a significant rise in plasma PRL levels. A significant rise in plasma PRL levels was also observed when larger doses of sulpiride were given 2 h after a first injection of the drug. Apomorphine was at least as effective an inhibitor of PRL secretion when given 2 h after sulpiride than when injected after saline. In vitro studies of dopaminergic binding sites revealed the presence, in pituitary glands of sulpiride-treated rats, of receptors not modified by the drug. These data suggest that the only plausible explanation for the ineffectiveness of the second of two consecutive injections of sulpiride is the development of a state of refractoriness of the mechanisms that subserve the release of PRL induced by suppression of the inhibitory dopaminergic tonus.

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

Hypothalamic dopamine and catechol oestrogens in rats with spontaneous pituitary tumours

1983 ◽  
Vol 96 (2) ◽  
pp. 347-352 ◽  
Author(s):  
R. A. Prysor-Jones ◽  
J. J. Silverlight ◽  
J. S. Jenkins
Keyword(s):  
Pituitary Gland ◽  
Plasma Prolactin ◽  
Pituitary Tumours ◽  
Dopamine Concentration ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Normal Rat ◽  
Old Rats ◽  
Hypothalamic Dopamine

Dopamine concentration within the hypothalamus and its depletion after the administration of α-methyl-para-tyrosine were measured in young rats and compared with values obtained in aged animals with and without spontaneously occurring pituitary tumours. Old rats had significantly reduced hypothalamic dopamine concentrations and there was less depletion of dopamine compared with young animals but there were no differences between tumorous and non-tumorous animals. Hyperprolactinaemia induced in young animals caused a much greater depletion of hypothalamic dopamine than in old tumorous rats with comparable plasma prolactin concentrations. The catechol oestrogen 2-hydroxyoestradiol inhibited the release of prolactin from normal rat pituitary glands in vitro but measurement of catechol oestrogens in the hypothalamus showed no differences between young and old tumorous or non-tumorous rats. It is concluded that reduced dopamine concentration and an impaired response to hyperprolactinaemia in old rats may facilitate the growth of prolactin-secreting tumours arising in the pituitary gland.

ETUDE DE L'ACTION DU FACTEUR HYPOTHALAMIQUE LRF (LH-RELEASING FACTOR) CHEZ LE RAT IN VIVO & IN VITRO

1967 ◽  
Vol 55 (3) ◽  
pp. 481-496 ◽  
Author(s):  
Marian Jutisz ◽  
Annette Bérault ◽  
Marie-Anne Novella ◽  
Geneviève Ribot
Keyword(s):  
Dose Response ◽  
Crude Extract ◽  
Response Curve ◽  
Assay Method ◽  
Hypothalamic Extract ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Releasing Effect

ABSTRACT A highly purified ovine LH-releasing factor (LRF) was obtained by a modification of the method previously described. After the fractionation of a crude hypothalamic extract on a Sephadex G-25 column, the LRF fraction was desalted and partially purified by chromatography on a Dowex 50 × 12 column and on an Amberlite CG 4B column. The last step of this method, chromatography on a CMC column, gave a purification of about 1600 times with respect to the crude extract. The action of this highly purified LRF preparation was studied on rat pituitary glands in vivo and in vitro. The method used in vivo was the evaluation of the LH-releasing effect of LRF in chronically ovariectomized, steroid-blocked rats (Ramirez & McCann 1963 b). A procedure was developed which allows a 4-fold concentration of the plasma LH from these rats, so that it can be assayed by a 4-point assay method. In the in vitro method, the pituitary glands of ovariectomized steroidblocked rats (Schally & Bowers 1964 a) were incubated in a Krebs-Ringer buffer with or without LRF, and the LH released into the medium was assayed using the O.A. A.D. method of Parlow. A dose-response curve was established between the log doses of LRF and the amount of LH released. This method can be used as a sensitive and specific assay for LRF. It was shown that a dose of 1.22 μg of LRF releases approximately 5 μg of LH per mg of pituitary tissue. This is about double of the amount of this hormone originally present in the pituitary glands of these rats (2.7 μg/mg). This leads us to the conclusion that the excess of this hormone was probably synthetized during the process of incubation. The amount of steroids injected as a blocking agents, appears to be very important for both in vivo and in vitro tests.

Heterogeneity of rat FSH by chromatofocusing: studies on in-vitro bioactivity of pituitary FSH forms and effect of neuraminidase treatment

1985 ◽  
Vol 105 (1) ◽  
pp. 17-27 ◽  
Author(s):  
W. F. P. Blum ◽  
G. Riegelbauer ◽  
D. Gupta
Keyword(s):  
Apparent Molecular Weight ◽  
Maximum Response ◽  
Dependent Manner ◽  
In Vitro Bioactivity ◽  
Response Curves ◽  
Neuraminidase Treatment ◽  
Rat Pituitary ◽  
Exclusion Chromatography ◽  
Reference Preparation

ABSTRACT This study concerned the resolution of rat pituitary FSH utilizing chromatofocusing. Among the 11 components resolved and positively identified, ten had apparent isoelectric points (pI) between 3·1 and 5·1. Approximately 1% of pituitary FSH eluted at pH 9·4. Treatment with varying amounts of neuraminidase followed by refocusing generated FSH components of higher pI values. Treatment with other glycosidases did not alter the elution characteristics in chromato-focusing, while exclusion chromatography established an inverse relationship between apparent molecular weight and pi. Dose–response curves of various FSH components and of the reference preparation in the current radioimmunoassay system were parallel to each other. A study of their in-vitro bioactivity, utilizing granulosa cells which produce a plasminogen activator due to FSH in a dose-dependent manner, provided the following evidence: increased acidity of the components led to (1) an increase of maximum response and (2) an increase of the dose necessary for half-maximum response. Considering the observed alterations in the hetereogeneity of FSH with changing physiological states of the animal, it is concluded that qualitative changes of the FSH molecule are perhaps involved in a modulatory role in the biopotencies of the hormone. J. Endocr. (1985) 105, 17–27

Influence of gonadal steroids on the time-course of release and synthesis of luteinizing hormone, follicle-stimulating hormone and prolactin from rat pituitary glands in vitro

1983 ◽  
Vol 96 (2) ◽  
pp. 171-179 ◽  
Author(s):  
Marta E. Apfelbaum
Keyword(s):  
Time Course ◽  
Follicle Stimulating Hormone ◽  
Gonadal Steroids ◽  
Regulatory Mechanisms ◽  
Ovariectomized Rats ◽  
Hormone Synthesis ◽  
The Third ◽  
Rat Pituitary ◽  
Pituitary Glands

The effect of the gonadal steroids on the time-course of release and synthesis of LH, FSH and prolactin was studied in vitro. Pituitary glands from ovariectomized rats were incubated for four sequential periods of 1 h in the presence or absence of 1·84 μmol oestradiol-17β/l, 3·44 μmol 5a-dihydrotestosterone/l or 31·80 μmol progesterone/l. The rate of release of LH was not affected by oestradiol or dihydrotestosterone, but was enhanced by progesterone after the third period of incubation. Synthesis of LH was increased by the three steroids tested, from 1 to 4 h of incubation, the effect being more marked for oestradiol than for the other steroids. The rate of release of FSH was depressed after 3 h whereas its synthesis was increased between 1 and 2 h, only in the presence of dihydrotestosterone. Synthesis of FSH was also stimulated by oestradiol after 2 h incubation but its release was not affected. Progesterone showed no effect on either the release or the synthesis of FSH. Although oestradiol and dihydrotestosterone induced a rise in both LH and FSH synthesis, the onset, magnitude and duration of the responses were different, indicating separate regulatory mechanisms. Oestradiol stimulated the rates of both release and synthesis of prolactin. The effect was already evident after 1 h of incubation and increased thereafter. On the contrary, progesterone treatment inhibited the release and synthesis of prolactin. The rate of synthesis decreased after 1 h of incubation, whereas release was depressed after 3 h. Dihydrotestosterone had no effect on the release and synthesis of prolactin. The evidence provided by this study indicates that the effect of the steroid hormones in vitro was predominantly on the synthesis of LH, FSH and prolactin. When changes in release of LH, FSH and prolactin occurred they were always preceded by alterations in hormone synthesis.

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