Lamprey GnRH-III Acts on Its Putative Receptor via Nitric Oxide to Release Follicle-Stimulating Hormone Specifically

2002 ◽  
Vol 227 (9) ◽  
pp. 786-793 ◽  
Author(s):  
W.H. Yu ◽  
S. Karanth ◽  
C.A. Mastronardi ◽  
S. Sealfon ◽  
C. Dean ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cultured Cells ◽  
Follicle Stimulating Hormone ◽  
The Other ◽  
Male Rats ◽  
Other Hand ◽  
Lh Rh ◽  
Stimulating Hormone

Lamprey gonadotropin-releasing hormone-III (I-GnRH-III), the putative follicle-stimulating hormone (FSH)-releasing factor (FSHRF), exerts a preferential FSH-releasing activity in rats both in vitro and in vivo. To test the hypothesis that I-GnRH-III acts on its own receptors to stimulate gonadotropin release, the functional activity of this peptide at mammalian (m) leutinizing hormone (LH)RH receptors transfected to COS cells was tested. I-GnRH-III activated m-LHRH receptors only at a minimal effective concentration (MEC) of 10–6 M, whereas m-LHRH was active at a MEC of 10–9 M, at least 1,000 times less than that required for I-GnRH-III. In 4-day monolayer cultured cells, I-GnRH-III was similarly extremely weak in releasing either LH or FSH, and, in fact, it released LH at a lower concentration (10–7 M) than that required for FSH release (10–6 M). In this assay, m-LHRH released both FSH and LH significantly at the lowest concentration tested (10–10 M). On the other hand, I-GnRH-III had a high potency to selectively release FSH and not LH from hemipituitaries of male rats. The results suggest that the cultured cells were devoid of FSHRF receptors, thereby resulting in a pattern of FSH and LH release caused by the LHRH receptor. On the other hand, the putative FSH-releasing factor receptor accounts for the selective FSH release by I-GnRH-III when tested on hemipituitaries. Removal of calcium from the medium plus the addition of EGTA, a calcium chelator, suppressed the release of gonadotropins induced by either I-GnRH-III or LHRH, indicating that calcium is required for the action of either peptide. Previous results showed that sodium nitroprusside, a releaser of nitric oxide (NO), causes the release of both FSH and LH from hemipituitaries incubated in vitro. In the present experiments, a competitive inhibitor of NO synthase, L-NG-monomethyl-l-arginine (300 μM) blocked the action of I-GnRH-III or partially purified FSHRF. The results indicate that I-GnRH-III and FSHRF act on putative FSHRF receptors by a calcium-dependent NO pathway.

scholarly journals Recombinant forms of rat and human luteinizing hormone and follicle-stimulating hormone; comparison of functions in vitro and in vivo

1998 ◽  
Vol 158 (3) ◽  
pp. 441-448 ◽  
Author(s):  
K Hakola ◽  
AM Haavisto ◽  
DD Pierroz ◽  
A Aebi ◽  
A Rannikko ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Cell Line ◽  
Follicle Stimulating Hormone ◽  
Tumor Cell Line ◽  
Male Rats ◽  
Rat Pituitary ◽  
Functional Features ◽  
Stimulating Hormone

We have previously described the preparation, purification and partial characterization of recombinant (rec) forms of rat luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In the present study, the special functional features of these hormones were studied further, in vitro and in vivo, and compared with human recLH and recFSH, as well as with human urinary choriongonadotropin (hCG) and rat pituitary LH (NIDDK-RP3). In radioreceptor assay, the affinity of hCG binding to rat testis membranes was 5-fold higher than that of human recLH and 100-fold higher than that of rat recLH. In in vitro bioassay, using dispersed adult mouse interstitial cells or a mouse Leydig tumor cell line (BLT-1), hCG and human recLH were 10- to 20-fold more potent than rat recLH. Correspondingly, rat pituitary LH was about 10-fold less potent than rat recLH, and evoked a maximum testosterone response that was about half of that elicited by the other LH/CG preparations. Rat recFSH was about 10-fold less potent than human recFSH in stimulating cAMP production of a mouse Sertoli cell line (MSC-1) expressing the recombinant rat FSH receptor. The circulating half-times (T1/2) of rat and human rec hormones were assessed after i.v. injections into adult male rats rendered gonadotropin-deficient by treatment with a gonadotropin-releasing hormone antagonist. A novel immunometric assay was used for the rat FSH measurements. In the one-component model the T1/2 values of rat and human recLH were 18.2 +/- 1.9 min (n = 7) and 44.6 +/- 3.1 min (n = 7) respectively and those of rat and human recFSH were 88.4 +/- 10.7 min (n = 6) and 55.0 +/- 4.2 min (n = 6) respectively; the two-component models revealed similar differences between the rec hormone preparations. Collectively, rat recLH was eliminated significantly faster from the circulation than human recLH (P < 0.0001). In contrast, the elimination of rat recFSH was significantly slower than that of human recFSH (P = 0.02). In conclusion, rat recFSH and rat recLH display lower biopotencies per unit mass than the respective human hormones in vitro, and also in vivo for LH. This is paralleled by shorter T1/2 of rat recLH than the respective human hormone in the circulation, whereas human recFSH has a shorter T1/2 than human FSH. The special functional features of the rat rec gonadotropins emphasize the use of these preparations on studies of gonadotropin function in the rat, an important animal model for reproductive physiology.

THE EFFECTS OF SYNTHETIC GONADOTROPHIN RELEASING FACTOR ON THE RELEASE OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE FROM OVINE PITUITARY TISSUE IN VITRO

1973 ◽  
Vol 58 (3) ◽  
pp. 387-391 ◽  
Author(s):  
D. B. CRIGHTON
Keyword(s):  
Luteinizing Hormone ◽  
Incubation Medium ◽  
Synthetic Peptides ◽  
Follicle Stimulating Hormone ◽  
The Other ◽  
Pituitary Tissue ◽  
Incubation System ◽  
Stimulating Hormone

SUMMARY A synthetic decapeptide gonadotrophin releasing factor was tested for effects on the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) using an ovine pituitary incubation system. The effects of other synthetic peptides used at similar doses were studied. The synthetic decapeptide consistently provoked significant increases in the LH content of the incubation medium at doses equal to or in excess of 0·5 ng/flask (0·2 ng/ml medium). Significant increases in the FSH content of the incubation medium at doses equal to or in excess of 0·25 ng/flask (0·1 ng/ml medium) were observed. The other synthetic peptides failed to influence LH or FSH release in vitro even at a dose 20–40 times greater. The results demonstrate that the decapeptide releases both LH and FSH from sheep pituitary tissue, suggesting that it may play a role in the release of both hormones in vivo in the sheep.

Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

1987 ◽  
Vol 52 (9) ◽  
pp. 2317-2325 ◽  
Author(s):  
Jan Hlaváček ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Walter Y. Chan ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
The Other ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Other Hand ◽  
Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

In vitro insulin-mimetic activity and in vivo metallokinetic feature of oxovanadium(IV)porphyrin complexes in healthy rats

2012 ◽  
Vol 16 (01) ◽  
pp. 114-121 ◽  
Author(s):  
Tapan K. Saha ◽  
Yutaka Yoshikawa ◽  
Hirouki Yasui ◽  
Hiromu Sakurai
Keyword(s):  
The Other ◽  
Insulin Mimetic ◽  
Other Hand ◽  
Better Than

We prepared [meso-tetrakis(4-carboxylatophenyl)porphyrinato]oxovanadium(IV) tetrasodium, ([VO(tcpp)]Na4), and investigated its in vitro insulin-mimetic activity and in vivo metallokinetic feature in healthy rats. The results were compared with those of previously proposed insulin-mimetic oxovanadium(IV)porphyrin complexes and oxovanadium(IV) sulphate. The in vitro insulin-mimetic activity and bioavailability of [VO(tcpp)]Na4 were considerably better than those of [meso-tetrakis (1-methylpyridinium-4-yl)porphyrinato]oxovanadium(IV)(4+) tetraperchlorate ([VO(tmpyp)](ClO4)4) and oxovanadium(IV) sulphate. On the other hand, [VO(tcpp)]Na4 and [meso-tetrakis(4-sulfonatophenyl) porphyrinato]oxidovanadate(IV)(4-)([VO(tpps)]) showed very similar in vitro insulin-mimetic activity and in vivo metallokinetic feature in healthy rats. In particular, the order of in vitro insulin-mimetic activity of the complexes was determined to be: [VO(tcpp)]Na4 ≈ [VO(tpps)] > ([VO(tmpyp)](ClO4)4 > oxovanadium(IV) sulphate.

scholarly journals Effects of cytoplasmic acidification on clathrin lattice morphology.

1989 ◽  
Vol 108 (2) ◽  
pp. 401-411 ◽  
Author(s):  
J Heuser
Keyword(s):  
Plasma Membrane ◽  
Cultured Cells ◽  
Membrane Receptors ◽  
The Other ◽  
Culture Dish ◽  
Initial Curvature ◽  
Internal Ph ◽  
Cytoplasmic Acidification

Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.

EFFECTS OF CASTRATION, AND TESTOSTERONE IN VITRO, ON THE HYPOTHALAMIC SYNTHESIS OF DIFFERENT PEPTIDE FRACTIONS

1975 ◽  
Vol 64 (1) ◽  
pp. 155-161 ◽  
Author(s):  
J. A. MOGUILEVSKY ◽  
M. A. ENERO ◽  
B. SZWARCFARB ◽  
D. DOSORETZ
Keyword(s):  
Luteinizing Hormone ◽  
Incubation Medium ◽  
Ammonium Acetate ◽  
Follicle Stimulating Hormone ◽  
The Other ◽  
Ovariectomized Rats ◽  
Small Peptides ◽  
Other Hand ◽  
Peptide Fractions

SUMMARY The incorporation of [3H]tyrosine ([3H]tyr) into different hypothalamic peptide fractions isolated from normal and castrated rats on a Sephadex G-25 column has been studied in vitro. Luteinizing hormone releasing factor (LH-RF) activity was determined in the different fractions by measuring their ability to elicit release of radioimmunoassayable luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in ovariectomized rats treated with oestrogen and progesterone. For further purification, the fraction with LH-RF activity was applied to a CM-Sephadex G-25 column eluted with a gradient of ammonium acetate. The large radioactive peptides emerged from the Sephadex G-25 column in fraction S-1, while the small peptides with LH-RF activity were eluted in fraction S-2. Gonadectomy significantly increased the incorporation of [3H]tyr into the peptides of fractions S-2. Only in the purified fraction with LH-RF activity was the radioactivity incorporated higher in gonadectomized than in normal rats. The enhanced incorporation in fraction CM-3 observed after castration implies an increase in the hypothalamic synthesis of peptides with LH-RF activity. The addition of testosterone (2 μg/ml) to the incubation medium of hypothalamus from gonadectomized rats, corrected these modifications. Gonadectomy decreased the incorporation of tyrosine into the large peptides, and incubation with testosterone corrected this change. The modifications in the incorporation of [3H]tyr into the large and small peptides produced by castration appear to indicate that gonadectomy, as well as stimulating the production of LH-RF, enhances the synthesis of other hypothalamic peptides while inhibiting the synthesis of proteins. On the other hand an increase in the breakdown of large peptides into small peptides cannot be excluded.

PHYSIOLOGICAL ACTIONS OF HUMAN FOLLICLE-STIMULATING HORMONE AND ITS β-SUBUNIT IN REPTILES

1977 ◽  
Vol 74 (3) ◽  
pp. 441-447 ◽  
Author(s):  
PAUL LICHT ◽  
ANTONELLA BONA GALLO ◽  
ANNE STOCKELL HARTREE ◽  
RATNA C. SHOWNKEEN
Keyword(s):  
Biological Activity ◽  
Follicle Stimulating Hormone ◽  
Β Subunit ◽  
Binding Assays ◽  
Mammalian Tissues ◽  
Stimulation Of ◽  
Stimulating Hormone

SUMMARY The actions of human follicle-stimulating hormone (hFSH) and its β-subunit were examined in several assays in reptiles, including effects on lizard testicular activity (growth and androgen production) in vivo, and stimulation of androgen production by snake testes and competition for binding of 125I-labelled hFSH in lizards and snakes in vitro. Binding was also examined with mammalian tissues. The hFSH was highly steroidogenic in the snake and lizard; otherwise results were similar to those observed in mammals. In all cases, the potency of the β-subunit was only a few per cent of the intact hormone. The potency of hFSH in vivo compared with NIH-FSH ovine standards was several 100 times greater than in vitro. Results for stimulation of androgen production in vivo closely paralleled those for binding assays in both reptiles and mammals. In contrast to previous results for ovine FSH β-subunit, human FSH β-subunit has little if any FSH biological activity in reptiles.

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