Isolation and characterization of a gonadotropin-releasing hormone binding protein in goldfish serum

Huang, Yaobo; Guo, Dacheng; Peter, Richard

doi:10.1016/0016-6480(91)90064-d

Cited by 12 publications

(4 citation statements)

References 28 publications

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“…There is a direct projection of cfGnRH-producing neurons from the ventral forebrain into the pituitary, while the cGnRH-II-producing neurons in the midbrain tegmentum do not appear to project to the pituitary [11]. Instead, cGnRH-II may reach the pituitary via the general circulation, by binding to serum GnRH binding proteins as in goldfish [30,31] and dogfish [32], or via the cerebrospinal fluid [10,33]. The fish used for these experiments were raised and kept in the laboratory hatchery.…”

Section: Discussionmentioning

confidence: 89%

Inhibitory and Stimulatory Interactions Between Endogenous Gonadotropin-Releasing Hormones in the African Catfish (Clarias gariepinus)1

Bosma

Rebers

Dijk

et al. 2000

Biology of Reproduction

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In the brain of all vertebrate classes, chicken (c) GnRH-II ([His(5), Trp(7),Tyr(8)]GnRH, cGnRH-II) is expressed in the mesencephalon. In addition, at least one other form of GnRH is expressed in the preoptical area/hypothalamus. In the human pituitary stalk and the mouse median eminence, cGnRH-II is present together with mammalian GnRH. Similarly, in the pituitary of several teleost fish (e.g., goldfish and eel, but not salmon or trout), a teleost GnRH is found together with cGnRH-II. These GnRHs are not colocalized in the same cells. Hence, these GnRH peptides may differentially regulate gonadotropin secretion and, in addition, may exert their effects simultaneously. The current study therefore investigated the effects of combinations of the two forms of GnRH present in the African catfish (Clarias gariepinus) pituitary-cGnRH-II and catfish GnRH ([His(5),Asn(8)]GnRH, cfGnRH)-on the cytosolic free calcium concentration ([Ca(2+)](i)) in single, Fura-2-loaded catfish gonadotrophs, as well as their effects on both in vitro and in vivo LH secretion. Both inhibitory and stimulatory effects of combinations of cfGnRH and cGnRH-II on [Ca(2+)](i) were observed, which were mirrored by their effects on both in vitro and in vivo LH secretion. The following pattern became apparent. The effect of intermediate or maximal effective cfGnRH doses was inhibited by the simultaneous presence of subthreshold or borderline effective cGnRH-II doses. Conversely, subthreshold or borderline effective concentrations of cfGnRH enhanced the effects of intermediate and maximal concentrations of cGnRH-II. In addition, combinations of cfGnRH and cGnRH-II concentrations that were equally active when tested separately showed an additive effect. The observed interactions between the two GnRHs may be of particular physiological relevance in the control of seasonal LH levels in the African catfish, as well as in other teleost species. Moreover, the occurrence of mutual inhibitory and stimulatory interactions between endogenous GnRHs may be a widespread aspect of GnRH action in vertebrates.

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Section: Discussionmentioning

confidence: 89%

Inhibitory and Stimulatory Interactions Between Endogenous Gonadotropin-Releasing Hormones in the African Catfish (Clarias gariepinus)1

Bosma

Rebers

Dijk

et al. 2000

Biology of Reproduction

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“…GnRH agonists were developed to increase potency over naturally occurring GnRH through enhanced binding affinity to the GnRH receptor and decrease enzymatic proteolysis . Despite the clinical success of the pharmacological application of GnRH derivatives, radiolabelled peptides are used for molecular imaging and radionuclide therapy of tumors . Many reports are available on the developing radiolabelled GnRH analogues.…”

Section: Introductionmentioning

confidence: 99%

Preclinical evaluation of new GnRH‐I receptor radionuclide therapy with ¹⁷⁷Lu‐peptide tracer

Zoghi

Nosrati

Rogni

et al. 2019

Labelled Comp Radiopharmac

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The purpose of this study was to develop preclinical evaluation of a novel radiolabeled gonadotropin-releasing hormone (GnRH) receptor targeting peptide for prostate cancer therapy. The new antiproliferative agent of GnRH-I analogue was developed on the basis of the D-Trp 6 -GnRH-I scaffold, and in vivo pharmacokinetics and receptor binding affinity were enhanced by the substitution of Gly-NHNH 2 for Gly-NH 2 at position 10 in D-Trp 6 -GnRH-I. To evaluate 177 Lu-DOTA-triptorelin-hydrazide as radionuclide therapy of tumor, the quality control tests and preclinical stage assessment were carried out.Solid-phase method was used to synthesize new peptide. Characterization and purity of peptide were done by mass spectroscopy and high-performance liquid chromatography (HPLC). In order to be utilized in targeted therapy, the new GnRH-I agonist was coupled with pSCN-Bn-DOTA. The precipitate crude of DOTA-triptorelin-hydrazide was then purified via preparative HPLC. At optimal conditions of time, temperature, ligand amount, and lutetium content, DOTA-triptorelin-hydrazide was labeled with 177 Lu (specific activity not less than 925 GBq/mg). Investigation of the in vivo biodistribution and in vitro studies for 177 Lu-DOTA-TRPHYD was performed in three different ways, and the binding of radiopeptide to GnRH receptors was expressed on the human cell lines using 125 I-labeled D-TRP 6 GnRH-I as a tracer, respectively.Synthesized novel GnRH-I was obtained with purity greater than 98%. Paper chromatography was found to be the most suitable with R f of the complex and observed radiochemical purity of RTLC and HPLC greater than 97%. For in vivo studies, 177 Lu-DOTA-triptorelin-hydrazide showed promising results with fast clearance from the blood and resulted in good T/NT ratios at 1, 4, and 24 hours postinjection and satisfactory biodistribution with no significant activity seen in normal tissue. The values of internalization efficiency and receptor affinity of new radiopeptide binding were IC 50 = 0.47 ± 0.06 vs 0.13 ± 0.01 nM for triptorelin and cellular uptake: 3.4 ± 0.7% at 1 hour and 6.8 ± 1.17% at 4 hours of the internal reference. The results showed a good stability and radiochemical purity of the obtained radioconjugate. For in vivo and in vitro studies, new radiopeptide showed a high uptake of 177 Lu conjugate in tumor and rapid clearance from the blood stream almost entirely via the

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“…Few reports on the production and use of radiolabeled GnRH analogs are available. 125 Ilabeled GnRH has been prepared and used for the study of receptor affinity of mutated GnRH receptors [17], permeability of LHRH into the arterial blood [18], protein binding determination [19], detection of pituitary and testis GnRH *Author for correspondence (E-mail: ajalilian@nrcam.org). receptors [20] and the study of receptor stimulation mechanisms [21].…”

Section: Introductionmentioning

confidence: 99%

Development of [111In]-DTPA-buserelin for GnRH receptor studies

Jalilian¹,

Shanehsazzadeh

Akhlaghi³

et al. 2010

Radiochimica Acta

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Buserelin was successively labeled with [ 111 In]-Indium chloride after residuation with DTPA-dianhydride. Radio-chromatography showed an overall radiochemical purity of >90% (RTLC) and > 95% (HPLC) at optimized conditions after labeling (specific activity: 400-450 GBq/M). The serum stability of the tracer was determined up to 24 h. The biodistribution of the tracer was determined in normal rats showing significant breast and ovaries uptakes 60 min post injection. MCF-7 cell binding of the tracer was > 98%. A significant testes uptake was demonstrated in normal male rats using SPECT studies.

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Isolation and characterization of a gonadotropin-releasing hormone binding protein in goldfish serum

Cited by 12 publications

References 28 publications

Inhibitory and Stimulatory Interactions Between Endogenous Gonadotropin-Releasing Hormones in the African Catfish (Clarias gariepinus)1

Inhibitory and Stimulatory Interactions Between Endogenous Gonadotropin-Releasing Hormones in the African Catfish (Clarias gariepinus)1

Preclinical evaluation of new GnRH‐I receptor radionuclide therapy with ¹⁷⁷Lu‐peptide tracer

Development of [111In]-DTPA-buserelin for GnRH receptor studies

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Isolation and characterization of a gonadotropin-releasing hormone binding protein in goldfish serum

Cited by 12 publications

References 28 publications

Inhibitory and Stimulatory Interactions Between Endogenous Gonadotropin-Releasing Hormones in the African Catfish (Clarias gariepinus)1

Inhibitory and Stimulatory Interactions Between Endogenous Gonadotropin-Releasing Hormones in the African Catfish (Clarias gariepinus)1

Preclinical evaluation of new GnRH‐I receptor radionuclide therapy with 177Lu‐peptide tracer

Development of [111In]-DTPA-buserelin for GnRH receptor studies

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Preclinical evaluation of new GnRH‐I receptor radionuclide therapy with ¹⁷⁷Lu‐peptide tracer