NEUTRALIZATION OF ACTIVITY OF CIRCULATING GONADOTROPHIC HORMONES BY ANTISERUM TO RAT PITUITARY

1963 ◽  
Vol 25 (4) ◽  
pp. 451-456 ◽  
Author(s):  
A. N. CONTOPOULOS ◽  
T. HAYASHIDA
Keyword(s):  
Serum Proteins ◽  
Follicular Development ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Male Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Hormone Activity ◽  
Immature Female ◽  
Rat Pituitary

SUMMARY Antiserum prepared by the immunization of rabbits, with homogenates of rat anterior pituitary gland according to a procedure previously outlined, was absorbed with homologous serum proteins and tissues to remove various non-specific antibodies. Varying levels of plasma from gonadectomized male rats, containing high levels of gonadotrophic hormone activity, were injected into hypophysectomized, immature female rats. The simultaneous injection of antiserum resulted in complete neutralization of gonadotrophic hormone as judged by the inhibition of ovarian and uterine weight responses and the extent of follicular development in the ovaries of the rats used for the bioassay. The degree of inhibition was dependent upon the relative amount of antiserum employed. Normal rabbit serum did not have any inhibitory effect. No detectable non-specific or toxic effects were noted in the animals injected with antiserum.

ABSENCE OF AN IMMUNOLOGICALLY DISTINCT FOLLICLE-STIMULATING HORMONE RELEASING FACTOR IN RAT STALK MEDIAN EMINENCE EXTRACTS

1976 ◽  
Vol 68 (1) ◽  
pp. 89-94 ◽  
Author(s):  
M. SHAHMANESH ◽  
S. L. JEFFCOATE
Keyword(s):  
Median Eminence ◽  
Male Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Pituitary Tissue ◽  
Rat Pituitary ◽  
Pre Treatment ◽  
Lh Rh ◽  
Dose Levels

SUMMARY Rat stalk median eminence (SME) extract was incubated with various quantities of an antiserum raised against synthetic luteinizing hormone releasing hormone (LH-RH) and the resulting material was used at two or more dose levels to stimulate release of LH and FSH from anterior pituitary tissue, obtained from male rats, incubated in vitro. The resulting dose–response lines were used to obtain the LH- and FSH-releasing potency of the material, expressed as a percentage of SME extract pre-incubated with normal rabbit serum. Treatment with various doses of antiserum reduced LH-releasing and FSH-releasing potencies to a similar extent. Stalk median eminence extract and synthetic LH-RH were incubated with antiserum and directly compared in the same experiment in vitro. The changes in LH and FSH release caused by pre-treatment with antibody were similar for SME extract and synthetic LH-RH. In a final experiment, SME extract was passed through a column of Sepharose 2B particles to which was coupled anti-LH-RH antibody. The resulting material, when mixed with synthetic LH-RH and used to stimulate rat pituitary tissue in vitro caused a similar increase in the LH- and FSH-releasing potencies of the synthetic decapeptide. It is concluded that rat SME extract contains a single releasing factor for LH and FSH immunologically indistinguishable from synthetic LH-RH.

Regulation of renal CYP4A expression and 20-HETE synthesis by nitric oxide in pregnant rats

2003 ◽  
Vol 285 (2) ◽  
pp. F295-F302 ◽  
Author(s):  
Mong-Heng Wang ◽  
Jishi Wang ◽  
Hsin-Hsin Chang ◽  
Barbara A. Zand ◽  
Miao Jiang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Rat Kidney ◽  
Late Pregnancy ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Male Rats ◽  
Pregnant Rats ◽  
Renal Vasoconstriction ◽  
Dependent Inhibition

20-Hydroxyeicosatetraenoic acid (20-HETE), which promotes renal vasoconstriction, is formed in the rat kidney primarily by cytochrome P-450 (CYP) 4A isoforms (4A1, 4A2, 4A3, 4A8). Nitric oxide (NO) has been shown to bind to the heme moiety of the CYP4A2 protein and to inhibit 20-HETE synthesis in renal arterioles of male rats. However, it is not known whether NO interacts with and affects the activity of CYP4A1 and CYP4A3, the major renal CYP4A isoforms in female rats. Incubation of recombinant CYP4A1 and 4A3 proteins with sodium nitroprusside (SNP) shifted the absorbance at 440 nm, indicating the formation of a ferric-nitrosyl-CYP4A complex. The absorbance for CYP4A3 was about twofold higher than that of CYP4A1. Incubation of SNP or peroxynitrite (PN; 0.01–1 mM) with CYP4A recombinant membranes caused a concentration-dependent inhibition of 20-HETE synthesis, with both chemicals having a greater inhibitory effect on CYP4A3-catalyzed activity. Moreover, incubation of CYP4A1 and 4A3 proteins with PN (1 mM) resulted in nitration of tyrosine residues in both proteins. In addition, PN and SNP inhibited 20-HETE synthesis in renal microvessels from female rats by 65 and 59%, respectively. We previously showed that microvessel CYP4A1/CYP4A3 expression and 20-HETE synthesis are decreased in late pregnancy. Therefore, we investigated whether such a decrease is dependent on NO, the synthesis of which has been shown to increase in late pregnancy. Administration of NG-nitro-l-arginine methyl ester (l-NAME) to pregnant rats for 6 days ( days 15- 20 of pregnancy) caused a significant increase in systolic blood pressure, which was prevented by concurrent treatment with the CYP4A inhibitor 1-aminobenzotriazole (ABT). Urinary NO2/NO3 excretion decreased by 40 and 52% in l-NAME- and l-NAME + ABT-treated groups, respectively. Interestingly, renal microvessel 20-HETE synthesis showed a marked increase following l-NAME treatment, and this increase was diminished with coadministration of ABT. These results demonstrate that NO interacts with CYP4A proteins in a distinct manner and it interferes with renal microvessel 20-HETE synthesis, which may play an important role in the regulation of blood pressure and renal function during pregnancy.

Mechanism of oleic acid-induced inhibition on gastric acid secretion in rats

1991 ◽  
Vol 260 (4) ◽  
pp. G564-G570 ◽  
Author(s):  
J. C. Rhee ◽  
T. M. Chang ◽  
K. Y. Lee ◽  
Y. H. Jo ◽  
W. Y. Chey
Keyword(s):  
Oleic Acid ◽  
Acid Secretion ◽  
Peptide Yy ◽  
Acid Output ◽  
Inhibitory Effect ◽  
Rabbit Serum ◽  
Similar Degree ◽  
Normal Rabbit Serum ◽  
Anesthetized Rats ◽  
Acid Acid

We investigated the existence of an enterogastrone in rats induced by duodenal administration of oleic acid. Acid secretion by the luminally perfused stomach was stimulated in anesthetized rats by intravenous infusion of 0.3 micrograms.kg-1.h-1 pentagastrin. Intraduodenal administration of 3 mmol of oleic acid produced a profound inhibition (94%) of pentagastrin-stimulated acid output in 10 rats (P less than 0.01). Of several peptides in plasma including secretin, neurotensin, somatostatin, and peptide YY, only secretin was found to increase significantly (P less than 0.001). A similar degree of inhibition of acid output (93%) was caused by porcine secretin, 5.6 pmol.kg-1.h-1, given intravenously to mimic the plasma level of secretin produced by oleic acid infusion. The inhibitory effect of oleic acid on the acid secretion was completely reversed by intravenous injection of a rabbit antisecretin serum but not by a normal rabbit serum. These observations strongly suggest that the inhibition was mediated via circulating secretin. The inhibition produced by either oleic acid or secretin was completely blocked by indomethacin. The blocking action was completely reversed by intravenous administration of 48 micrograms.kg-1.h-1 prostaglandin E2. We conclude that endogenous secretin is a major enterogastrone released by oleic acid in anesthetized rats and that the inhibitory action of secretin requires endogenous prostaglandins.

Effects of acute administration of 2-hydroxylated metabolites of oestrogens on LH and prolactin secretion in male and female prepubertal rats

1984 ◽  
Vol 103 (3) ◽  
pp. 317-325
Author(s):  
A. K. Brar ◽  
G. Fink
Keyword(s):  
Plasma Concentration ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Female Rat ◽  
Uterine Weight ◽  
Immature Female ◽  
Male And Female ◽  
Immature Male ◽  
Lh Release

ABSTRACT The effects of catechol oestradiol and catechol oestrone on the release of LH and prolactin were investigated in immature male and female Wistar rats. In male rats both catechol oestradiol and catechol oestrone significantly increased the plasma concentration of LH, and catechol oestradiol but not catechol oestrone significantly increased the plasma concentration of prolactin and decreased the pituitary concentration of LH. The parent oestrogens, oestradiol-17β and oestrone, had no effect on plasma LH concentrations, but both increased significantly the plasma concentration of prolactin, and oestrone but not oestradiol-17β increased the pituitary concentration of LH. In immature female rats, catechol oestradiol inhibited the surge of LH and the increase in uterine weight induced by injecting pregnant mare serum gonadotrophin (PMSG). The injection of oestrone induced an increase in the plasma concentration of LH which was about nine times greater than that produced by oestradiol-17β. There were no significant differences in the effects of these steroids on plasma prolactin concentration. These results (i) confirm that in the immature male rat catechol oestrogens can stimulate LH release and show that catechol oestradiol can increase prolactin release, (ii) show that catechol oestradiol can inhibit the stimulatory effects of PMSG on LH release and uterine weight in the immature female rat, and (iii) demonstrate that oestrone can stimulate LH release in the immature female rat. J. Endocr. (1984) 103, 317-325

Sites of action of testosterone and estradiol on longitudinal bone growth

1983 ◽  
Vol 244 (2) ◽  
pp. E135-E140 ◽  
Author(s):  
J. O. Jansson ◽  
S. Eden ◽  
O. Isaksson
Keyword(s):  
Replacement Therapy ◽  
Bone Growth ◽  
Body Weight Gain ◽  
Inhibitory Effect ◽  
Body Growth ◽  
Female Rats ◽  
Male Rats ◽  
Longitudinal Bone Growth ◽  
Sites Of Action ◽  
Different Doses

In this study the mechanisms by which sex steroids influence body growth were investigated. The effect of different doses of testosterone propionate on longitudinal bone growth and body weight gain was studied in a) gonadectomized male rats, b) gonadohypophysectomized male rats, and c) gonadohypophysectomized male rats given replacement therapy with bovine growth hormone (bGH). The effect of different doses of estradiol benzoate on the same growth parameters was studied in female rats divided into the same experimental groups as the males. Accumulated longitudinal bone growth was determined using oxytetracycline as an intravital marker. Testosterone caused a dose-dependent increase in longitudinal bone growth in gonadectomized male rats. In contrast, testosterone exerted no significant increase in longitudinal bone growth in gonadohypophysectomized male rats with and without bGH replacement therapy. Treatment with estrogen inhibited longitudinal bone growth and body weight gain. The inhibitory effect of estradiol was approximately the same in gonadohypophysectomized female rats given bGH replacement therapy as in gonadectomized female rats. The results suggest that testosterone exerts its stimulatory effect on body growth mainly by modulating hypothalamopituitary functions, e.g., by altering the secretory pattern of GH. On the other hand, it seems that changes in the hypothalamopituitary functions are less significant for the inhibitory effect of estradiol on body growth. It is concluded from this study that the sites of action for estrogen and testosterone in modulating body growth in the rat are different.

scholarly journals Effects of hypothyroidism on ovarian hormone secretion and follicular development in immature female rats

1997 ◽  
Vol 73 ◽  
pp. 103
Author(s):  
Minoru Hatsula ◽  
Kazuhiro Tamura ◽  
Gen Watanabe ◽  
Kazuyoshi Taya ◽  
Hiroshi Kogo Kogo
Keyword(s):  
Hormone Secretion ◽  
Follicular Development ◽  
Female Rats ◽  
Ovarian Hormone ◽  
Immature Female

BIOLOGICAL EFFECTS OF HUMAN URINARY FOLLICLE STIMULATING HORMONE

1970 ◽  
Vol 63 (3) ◽  
pp. 454-475 ◽  
Author(s):  
P. Petrusz ◽  
C. Robyn ◽  
E. Diczfalusy
Keyword(s):  
Biological Effects ◽  
Follicle Stimulating Hormone ◽  
Interstitial Cells ◽  
Female Rats ◽  
Male Rats ◽  
Weight Increase ◽  
Uterine Weight ◽  
Immature Female ◽  
Ovarian Weight ◽  
Female Mice

ABSTRACT The biological effects of human follicle stimulating hormone (FSH) preparations were studied in intact immature female mice and in hypophysectomized immature female and male rats, following the complete neutralization of the luteinizing hormone (LH) content of human urinary menopausal gonadotrophin (HMG) preparations having – prior to neutralization – FSH:LH ratios ranging between 1.0 and 500.0. Neutralization of LH was achieved by the addition of rabbit anti-human chorionic gonadotrophin (HCG) sera of known anti-LH potency. The amount of anti-LH employed was 1.5 to 730 times more than that required for 100% neutralization. In intact immature female mice, such »LH-free« FSH preparations induced an increased ovarian weight, follicle stimulation, as well as a uterine weight increase. In immature hypophysectomized female rats, »LH-free« FSH preparations induced ovarian weight increase, growth and maturation of the Graafian follicles without repair of the deficient interstitial cells and without any signs of luteinization. These ovarian changes were associated with an increase in uterine weight and with vaginal cornification. In view of these data, it is concluded that human urinary FSH per se is capable of inducing oestrogen synthesis in hypophysectomized female rats. In immature hypophysectomized male rats, »LH-free« FSH preparations induced testicular enlargement without any stimulation of the testicular interstitial cells and without any growth of the ventral prostate and seminal vesicles. The same effects were obtained following a prolonged administration (3 weeks); spermiogenesis was stimulated, but no mature spermatozoa were found.

Partial purification of antigens collected during in vitro cultivation of the larval stages of Taenia pisiformis

Parasitology ◽  
1976 ◽  
Vol 72 (3) ◽  
pp. 269-279 ◽  
Author(s):  
M. D. Rickard ◽  
J. C. Katiyar
Keyword(s):  
Protective Immunity ◽  
Culture Medium ◽  
Serum Proteins ◽  
Skin Tests ◽  
Rabbit Serum ◽  
Partial Purification ◽  
In Vitro Cultivation ◽  
Normal Rabbit Serum ◽  
Skin Reactions

SummaryLarvae of Taenia pisiformis were cultured in vitro in medium containing 2·5, 5 or 20% (v/v) of normal rabbit serum (NRS). Greatest development occurred in 20% NRS, and the potency of antigens collected in medium from each culture tested by intradermal (i/d) skin tests in infected rabbits paralleled the in vitro growth rate of larvae. ‘Culture’ antigens from 5% NRS stimulated good immunity in rabbits to a challenge infection with T. pisiformis eggs, although they were poorly reactive in skin tests.T. pisiformis larvae were also cultured in 10% (v/v) of nitrates of serum reduced to one-half of its volume by passage through 300 000 MW cut oif (XM300F) or 100000 MW cut off (XM100F) ultrafiltration membranes. Larvae cultured using XM300F had growth rates comparable with those cultured in 20% NRS, and the antigens released into the culture medium had equal potency in i/d tests and in stimulating protective immunity in rabbits. Larvae did not develop in XM100F orproduce skin-reactive or protective antigens.Crude ‘culture’ antigen from cultures in 20% NRS was separated into 4 fractions by nitration on Sephadex G200. All of these fractions gave i/d skin reactions in infected rabbits. Fraction 3 (F3) was the most active, but was shown by acrylamide gel electrophoresis and immunoelectrophoresis to be highly contaminated with rabbit serum proteins. F3 was separated into fractions on DEAE-Sephadex A50, and the third fraction from this was as active as the original culture medium in i/d skin tests, but had only 5% of the original protein concentration. Electrophoresis demonstrated few serum contaminants, and 2 indistinct protein bands that were not present in a similar fraction of NRS.Neither Sephadex G200 F3 nor DEAE-Sephadex F3 stimulated protective immunity in rabbits, suggesting that antigens stimulating immunity against the establishment of T. pisiformis in rabbits and those provoking cell-mediated immune reactions may be different.

Inhibition of cytochrome P-450 C17 enzyme by a GnRH agonist in ovarian follicles from gonadotropin-stimulated rats

2007 ◽  
Vol 292 (5) ◽  
pp. E1456-E1464 ◽  
Author(s):  
Griselda Irusta ◽  
Fernanda Parborell ◽  
Marta Tesone
Keyword(s):  
Direct Action ◽  
Regulatory Protein ◽  
Follicular Development ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Serum Progesterone ◽  
Protein Levels ◽  
Androgen Synthesis ◽  
Cytochrome P 450

Our objective was to study the direct action of a GnRH-I agonist, leuprolide acetate (LA), on ovarian steroidogenesis in preovulatory follicles obtained from equine chorionic gonadotropin (eCG)-treated rats. Previously, we have demonstrated an inhibitory effect of LA on steroidogenesis and follicular development. In this study, we tested the hypothesis that gonadotropin-releasing hormone (GnRH) exerts its negative effect on follicular development by inhibiting thecal cytochrome P-450 C17 (P450C17) α-hydroxylase expression and, consequently, androgen synthesis. Studies were carried out in prepubertal female rats injected with either eCG (control) or eCG plus LA (LA) and killed at different time points. Immunohistochemical studies indicated that LA induced steroidogenic acute regulatory protein (StAR) expression mainly in theca cells of preantral and antral follicles. In addition, serum progesterone levels increased significantly ( P < 0.05), whereas those of androsterone decreased ( P < 0.05) after 8 h of LA treatment. This inhibition caused by LA seemed to be a consequence of the decreased expression of follicular P450C17 α-hydroxylase, as demonstrated by Western blot and RT-PCR techniques. In vitro studies using follicles isolated from 48-h-eCG-treated rats and cultured with LA showed a significant ( P < 0.05) inhibition of FSH-induced androsterone follicular content as well as P450C17 α-hydroxylase protein levels, as determined by Western analysis. However, LA increased StAR protein expression in these follicles without significant changes in P450scc enzyme levels. Taking all these findings into account, we suggest that GnRH-I exerts a direct inhibitory action on gonadotropin-induced follicular development by decreasing the temporal expression of the P450C17 enzyme and, consequently, androgen production, thus reducing the supply of estrogens available to developing follicles.

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