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Di Fiore MM, Santillo A, Falvo S, Pinelli C. Celebrating 50+ years of research on the reproductive biology and endocrinology of the green frog: An overview. Gen Comp Endocrinol 2020; 298:113578. [PMID: 32739437 DOI: 10.1016/j.ygcen.2020.113578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/20/2020] [Accepted: 07/25/2020] [Indexed: 12/30/2022]
Abstract
This issue is dedicated to the late Professor Giovanni Chieffi, and this article is an overview of the research on Comparative Endocrinology of reproduction using Rana esculenta (alias Pelophylax esculentus) as a model system. Starting from the early 1970s till today, a large quantity of work have been conducted both in the fields of experimental endocrinology and in the definition of the diffuse neuroendocrine system, with a major focus on the increasing role of regulatory peptides. The various aspects investigated concerned the histological descriptions of principal endocrine glands of the hypothalamic-pituitary-gonadal (HPG) axis, the localization and distribution in the HPG of several different substances (i.e. neurosteroids, hypothalamic peptide hormones, pituitary gonadotropins, gonadal sex steroids, and other molecules), the determination of sex hormone concentrations in both serum and tissues, the hormone manipulations, as well as the gene and protein expression of steroidogenic enzymes and their respective receptors. All together these researches, often conducted considering different periods of the annual reproductive cycle of the green frog, allowed to understand the mechanism of cascade control/regulation of the HPG axis of R. esculenta, characterizing the role of different hormones in the two sexes, and testing the hypotheses about the function of single hormones in different target organs. It becomes evident from the review that, in their simplest form, several features of this species are specular as compared to those of other vertebrate species and that reproduction in this frog species is either under endogenous multi-hormonal control or by a wide array of different factors. Our excursus of this research, spanning almost five decades, shows that R. esculenta has been intensively and successfully used as an animal model in reproductive endocrinology as well as several field studies such as those involving environmental concerns that focus on the effects of endocrine disruptors and other environmental contaminants.
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Affiliation(s)
- Maria Maddalena Di Fiore
- Department of Environmental, Biological and Pharmaceutical Sciences & Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy
| | - Alessandra Santillo
- Department of Environmental, Biological and Pharmaceutical Sciences & Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy
| | - Sara Falvo
- Department of Environmental, Biological and Pharmaceutical Sciences & Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy
| | - Claudia Pinelli
- Department of Environmental, Biological and Pharmaceutical Sciences & Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy.
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Zoghi M, Attar Nosrati S, Rogni F, Mahdiyani B. Evaluation of 111In-Labeled GnRH-I Tracer for SPECT Tumor Imaging. RADIOCHEMISTRY 2019. [DOI: 10.1134/s1066362219020164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Zoghi M, Nosrati SA, Rogni F, Rajabifar S. Preparation of a radiolabeled GnRH-I analogue derivative with 111 In as a new anti-proliferative agent. J Labelled Comp Radiopharm 2018; 61:903-911. [PMID: 30109712 DOI: 10.1002/jlcr.3677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/07/2018] [Accepted: 08/04/2018] [Indexed: 01/19/2023]
Abstract
The new GnRH-Ιanalogue developed in this paper was based on the D-Trp6 -GnRH-Ι-scaffold, and its potency was increased by the replacement Gly-NH2 by NH-NH2 binding to the Gly at position 10. Triptorelin-Hydrazide analogue was synthesized using solid phase. For 111 In labeling, synthesized peptide was followed by conjugation with DOTA using pSCN-Bn-DOTA. The conjugated Triptorelin-Hydrazide was labeled with 500-550 MBq of 111 In-chloride (in 0.2 M HCl). At optimized conditions after labeling, radio-chromatography showed radiochemical purity of approximately equal to 98% (RTLC) and greater than 95% (HPLC). The serum stability of the tracer was determined up to 24 hr. Binding affinities of Triptorelin-Hydrazide analogue were determined in a binding assay for both human and rat GnRH receptors. For in vivo studies, 111 In-peptide was injected intravenously via the tail vein into rats and significant ovaries uptake consist with reported GnRH receptor mappings. In vitro radioligand binding assays performed with GnRHR-expressing human cell lines using 125 I-Triptorelin as the standard radioligand. The quantities of internalization efficiency and receptor affinity of the new radioligand were IC50 = 0.20 ± 0.04 nM vs 0.13 ± 0.08 nM for Triptorelin and internalization: 3.5 ± 0.9% at 1 hr and 12.8 ± 1.8% at 4 hr of the internal reference.
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Affiliation(s)
- Masoumeh Zoghi
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
| | - Sima Attar Nosrati
- Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Faramarz Rogni
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
| | - Saaed Rajabifar
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
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Zoghi M, Jalilian AR, Niazi A, Johari-Daha F, Alirezapour B, Ramezanpour S. Development of a (68)Ga-peptide tracer for PET GnRH1-imaging. Ann Nucl Med 2016; 30:400-8. [PMID: 27083468 DOI: 10.1007/s12149-016-1074-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/25/2016] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Total synthesis, quality control and preclinical evaluation of [(68)Ga]-DOTA-triptorelin ([(68)Ga]-DOTA-TRP) is reported as a possible PET radiotracer for GnRH receptor imaging. METHODS DOTA-TRP was totally synthesized in two steps and after characterization went through radiolabelling optimization studies followed by tracer stability. The biodistribution of the tracer in normal male rats and 4T1 tumour-bearing mice was performed in 120 min after i.v. injection. RESULTS The peptide and the conjugates were synthesized with >95 % chemical purity. [(68)Ga]-DOTA-TRP complex was prepared in high radiochemical purity (>99 %, ITLC, HPLC) and specific activity of 1400-2100 MBq/nM at 95 °C using 40-60 μg of the peptide in 5-7 min followed by solid phase purification. The IC50 [nM] DOTA-TRP was comparable to the intact peptide, 0.11 ± 0.01 and 0.22 ± 0.05, respectively. The biodistribution of the tracer demonstrated kidney, stomach, and testes significant uptake, all in accordance with GnRH receptor ligands. Significant tumour uptake was observed in 4T1 tumour-bearing female mice 30-120 min post-injection with tumour:blood and tumour:muscle ratios of 28 and >50 in 60 min, respectively. Kidney is rapidly washed from the tracer. [(68)Ga]-DOTA-TRP can be proposed as a possible tracer for GnRH-R imaging studies.
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Affiliation(s)
- Masoumeh Zoghi
- Department of Chemistry, Faculty of Science, Arak Branch, Islamic Azad University, Arak, Iran
| | - Amir R Jalilian
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran.
| | - Ali Niazi
- Department of Chemistry, Faculty of Science, Arak Branch, Islamic Azad University, Arak, Iran
| | - Fariba Johari-Daha
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
| | - Behrouz Alirezapour
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
| | - Saeed Ramezanpour
- Peptide Chemistry Research Center, K. N. Toosi University of Technology, Tehran, Iran
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Ciaramella V, Meccariello R, Chioccarelli T, Sirleto M, Fasano S, Pierantoni R, Chianese R. Anandamide acts via kisspeptin in the regulation of testicular activity of the frog, Pelophylax esculentus. Mol Cell Endocrinol 2016; 420:75-84. [PMID: 26586207 DOI: 10.1016/j.mce.2015.11.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/12/2015] [Accepted: 11/09/2015] [Indexed: 11/26/2022]
Abstract
In the frog Pelophylax esculentus, the endocannabinoid anandamide (AEA) modulates Gonadotropin Releasing Hormone (GnRH) system in vitro and down-regulates steroidogenic enzymes in vivo. Thus, male frogs were injected with AEA ± SR141716A, a cannabinoid receptor 1 (CB1) antagonist, to evaluate possible effects on GnRH and Kiss1/Gpr54 systems, gonadotropin receptors and steroid levels. In frog diencephalons, AEA negatively affected both GnRH and Kiss1/Gpr54 systems. In testis, AEA induced the expression of gonadotropin receptors, cb1, gnrh2 and gnrhr3 meanwhile reducing gnrhr2 mRNA and Kiss1/Gpr54 proteins. Furthermore, aromatase (Cyp19) expression increased in parallel to testosterone decrease and estradiol increase. In vitro treatment of testis with AEA revealed direct effects on Cyp19 and induced the expression of the AEA-degrading enzyme Faah. Lastly, AEA effects on Faah were counteracted by the antiestrogen ICI182780, indicating estradiol mediated effect. In conclusion, for the first time we show in a vertebrate that AEA regulates testicular activity through kisspeptin system.
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Affiliation(s)
- Vincenza Ciaramella
- Dipartimento di Medicina Sperimentale sez "F. Bottazzi", Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Rosaria Meccariello
- Dipartimento di Scienze Motorie e del Benessere, Università di Napoli Parthenope, Via Medina 40, 80133 Napoli, Italy.
| | - Teresa Chioccarelli
- Dipartimento di Medicina Sperimentale sez "F. Bottazzi", Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Monica Sirleto
- Dipartimento di Scienze Motorie e del Benessere, Università di Napoli Parthenope, Via Medina 40, 80133 Napoli, Italy.
| | - Silvia Fasano
- Dipartimento di Medicina Sperimentale sez "F. Bottazzi", Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Riccardo Pierantoni
- Dipartimento di Medicina Sperimentale sez "F. Bottazzi", Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Rosanna Chianese
- Dipartimento di Medicina Sperimentale sez "F. Bottazzi", Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
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Chianese R, Ciaramella V, Scarpa D, Fasano S, Pierantoni R, Meccariello R. Anandamide regulates the expression of GnRH1, GnRH2, and GnRH-Rs in frog testis. Am J Physiol Endocrinol Metab 2012; 303:E475-87. [PMID: 22669247 DOI: 10.1152/ajpendo.00086.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Gonadotropin-releasing hormone (either GnRH1 or GnRH2) exerts a local activity in vertebrate testis, including human testis. Relationships between endocannabinoid (eCB) and GnRH systems in gonads have never been elucidated in any species so far. To reveal a cross-talk between eCBs and GnRH at testicular level, we characterized the expression of GnRH (GnRH1 and GnRH2) as well as GnRH receptor (GnRH-R1, -R2, and -R3) mRNA in the testis of the anuran amphibian Rana esculenta during the annual sexual cycle; furthermore, the corresponding transcripts were localized inside the testis by in situ hybridization. The possible endogenous production of the eCB, anandamide (AEA), was investigated in testis by analyzing the expression of its biosynthetic enzyme, Nape-pld. Incubations of testis pieces with AEA were carried out in the postreproductive period (June) and in February, when a new spermatogenetic wave takes place. In June, AEA treatment significantly decreased GnRH1 and GnRH-R2 mRNA, stimulated the transcription of GnRH2 and GnRH-R1, and did not affect GnRH-R3 expression. In February, AEA treatment upregulated GnRH2 and GnRH-R3 mRNA, downregulated GnRH-R2, and did not affect GnRH1 and GnRH-R1 expression. These effects were mediated by type 1 cannabinoid receptor (CB1) since they were fully counteracted by SR141716A (Rimonabant), a selective CB1 antagonist. In conclusion, eCB system modulates GnRH activity in frog testis during the annual sexual cycle in a stage-dependent fashion.
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Affiliation(s)
- Rosanna Chianese
- Dipartimento di Medicina Sperimentale sez F. Bottazzi, Seconda Università di Napoli, via Costantinopoli 16, 80138 Naples, Italy
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Chianese R, Ciaramella V, Fasano S, Pierantoni R, Meccariello R. Anandamide modulates the expression of GnRH-II and GnRHRs in frog, Rana esculenta, diencephalon. Gen Comp Endocrinol 2011; 173:389-95. [PMID: 21802420 DOI: 10.1016/j.ygcen.2011.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 06/17/2011] [Accepted: 07/08/2011] [Indexed: 10/18/2022]
Abstract
In the hypothalamus, endocannabinoids affect neuroendocrine activity by means of Gonadotropin-Releasing-Hormone-I (GnRH-I) inhibition. Since most vertebrates, human included, possess at least two GnRH molecular forms, the aim of this work was to investigate the effect of endocannabinoids on GnRH molecular forms other than GnRH-I and on GnRHRs. Thus, we cloned GnRH precursors as well as GnRH receptors (GnRHR-I, GnRHR-II, GnRHR-III) from the diencephalons of the anuran amphibian, Rana esculenta. GnRH-II expression was evaluated in pituitary, whole brain, spinal cord, hindbrain, midbrain and forebrain during the annual sexual cycle. Then, in post-reproductive period (May), GnRH-I, GnRH-II and GnRHRs expression was evaluated by quantitative real time (qPCR) after incubation of diencephalons with the endocannabinoid anandamide (AEA). AEA significantly decreased GnRH-I and GnRH-II expression, up regulated GnRHR-I and GnRHR-II mRNA and it had no effect upon GnRHR-III expression. These effects were counteracted by SR141716A (Rimonabant), a selective antagonist of type I cannabinoid receptor (CB1). In conclusion our results demonstrate a CB1 receptor dependent modulation of GnRH system expression rate (both ligands and receptors) in frog diencephalons. In particular, we show that AEA, besides GnRH-I, also acts on GnRH-II expression.
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Affiliation(s)
- Rosanna Chianese
- Dipartimento di Medicina Sperimentale sez F. Bottazzi, Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
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Chianese R, Chioccarelli T, Cacciola G, Ciaramella V, Fasano S, Pierantoni R, Meccariello R, Cobellis G. The contribution of lower vertebrate animal models in human reproduction research. Gen Comp Endocrinol 2011; 171:17-27. [PMID: 21192939 DOI: 10.1016/j.ygcen.2010.12.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 12/11/2010] [Accepted: 12/16/2010] [Indexed: 01/16/2023]
Abstract
Many advances have been carried out on the estrogens, GnRH and endocannabinoid system that have impact in the reproductive field. Indeed, estrogens, the generally accepted female hormones, have performed an unsuspected role in male sexual functions thanks to studies on non-mammalian vertebrates. Similarly, these animal models have provided important contributions to the identification of several GnRH ligand and receptor variants and their possible involvement in sexual behavior and gonadal function regulation. Moreover, the use of non-mammalian animal models has contributed to a better comprehension about the endocannabinoid system action in several mammalian reproductive events. We wish to highlight here how non-mammalian vertebrate animal model research contributes to advancements with implications on human health as well as providing a phylogenetic perspective on the evolution of reproductive systems in vertebrates.
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Affiliation(s)
- Rosanna Chianese
- Dipartimento di Medicina Sperimentale, Seconda Università degli Studi di Napoli, via Costantinopoli 16, 80138 Napoli, Italy
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Jalilian AR, Shanehsazzadeh S, Akhlaghi M, Kamali-dehghan M, Moradkhani S. Development of [111In]-DTPA-buserelin for GnRH receptor studies. RADIOCHIM ACTA 2010. [DOI: 10.1524/ract.2010.1689] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Jalilian AR, Shanehsazzadeh S, Akhlaghi M, Garousi J, Rajabifar S, Tavakoli MB. Preparation and biodistribution of [67Ga]-DTPA-gonadorelin in normal rats. J Radioanal Nucl Chem 2008. [DOI: 10.1007/s10967-007-7241-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Meccariello R, Franzoni MF, Chianese R, Cottone E, Scarpa D, Donna D, Cobellis G, Guastalla A, Pierantoni R, Fasano S. Interplay between the endocannabinoid system and GnRH-I in the forebrain of the anuran amphibian Rana esculenta. Endocrinology 2008; 149:2149-58. [PMID: 18218699 DOI: 10.1210/en.2007-1357] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The morphofunctional relationship between the endocannabinoid system and GnRH activity in the regulation of reproduction has poorly been investigated in vertebrates. Due to the anatomical features of lower vertebrate brain, in the present paper, we chose the frog Rana esculenta (anuran amphibian) as a suitable model to better investigate such aspects of the reproductive physiology. By using double-labeling immunofluorescence aided with a laser-scanning confocal microscope, we found a subpopulation of the frog hypothalamic GnRH neurons endowed with CB1 cannabinoid receptors. By means of semiquantitative RT-PCR assay, we have shown that, during the annual sexual cycle, GnRH-I mRNA (formerly known as mammalian GnRH) and CB1 mRNA have opposite expression profiles in the brain. In particular, this occurs in telencephalon and diencephalon, the areas mainly involved in GnRH release and control of the reproduction. Furthermore, we found that the endocannabinoid anandamide is able to inhibit GnRH-I mRNA synthesis; buserelin (a GnRH agonist), in turn, inhibits the synthesis of GnRH-I mRNA and induces an increase of CB1 transcription. Our observations point out the occurrence of a morphofunctional anatomical basis to explain a reciprocal relationship between the endocannabinoid system and GnRH neuronal activity.
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Affiliation(s)
- Rosaria Meccariello
- Dipartimento di Studi delle Istituzioni e dei Sistemi Territoriali, Università di Napoli Parthenope, 80133 Napoli, Italy
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De Rienzo G, Aniello F, Branno M, Izzo G, Minucci S. The expression level of frog relaxin mRNA (fRLX), in the testis of Rana esculenta, is influenced by testosterone. J Exp Biol 2006; 209:3806-11. [PMID: 16985197 DOI: 10.1242/jeb.02424] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Frog relaxin (fRLX) belongs to the relaxin/insulin gene family present in the testis of Rana esculenta and is specifically expressed by Leydig cells. Since the expression of fRLX transcript changes during the reproductive cycle and is more abundant when circulating levels of androgens are relatively high, we investigated the effect(s) of testosterone and its antagonist (cyproterone acetate, CPA) on its expression pattern, in the testis of the frog Rana esculenta. Results from in vivoand in vitro experiments demonstrate that testosterone strongly induces a significant increase of fRLX mRNA expression in frog testes and, this effect is counteracted by CPA, supporting the existence of intratesticular (autocrine/paracrine) mechanisms of action. Interestingly, in both the control and testosterone-treated testes, fRLX mRNA expression was markedly decreased 24 h post-treatment, as compared to that measured at 2 h and 8 h post-treatment, suggesting that factor(s), other than testosterone, may act(s) in controlling its expression. In addition, RT-PCR analysis and in situ hybridization performed on frog testis injected with CPA for 15 days, on alternate days, showed a strong decrease of fRLX expression, suggesting that CPA counteracts the effect of testosterone on fRLX expression. Taken together our results strongly indicate that changes in the production, by the Leydig cells, of both testosterone and fRLX may represent a marker for the study of Leydig cell activity in the testis of the frog Rana esculenta.
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Affiliation(s)
- Gianluca De Rienzo
- Dipartimento di Medicina Sperimentale, Sez. Fisiologia Umana e Funzioni Biologiche Integrate F. Bottazzi, Seconda Università di Napoli, via Costantinopoli 16, 80138 Napoli, Italy
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Tsai PS, Kessler AE, Jones JT, Wahr KB. Alteration of the hypothalamic-pituitary-gonadal axis in estrogen- and androgen-treated adult male leopard frog, Rana pipiens. Reprod Biol Endocrinol 2005; 3:2. [PMID: 15642123 PMCID: PMC548137 DOI: 10.1186/1477-7827-3-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 01/10/2005] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Gonadal steroids, in particular 5 alpha-dihydrotestosterone (DHT) and 17 beta-estradiol (E2), have been shown to feed back on the hypothalamic-pituitary-gonadal (HPG) axis of the ranid frog. However, questions still remain on how DHT and E2 impact two of the less-studied components of the ranid HPG axis, the hypothalamus and the gonad, and if the feedback effects are consistently negative. Thus, the goal of the study was to examine the effects of DHT and E2 upon the HPG axis of the gonadally-intact, sexually mature male leopard frogs, Rana pipiens. METHODS R. pipiens were implanted with silastic capsules containing either cholesterol (Ch, a control), DHT, or E2 for 10 or 30 days. At each time point, steroid-induced changes in hypothalamic GnRH and pituitary LH concentrations, circulating luteinizing hormone (LH), and testicular histology were examined. RESULTS Frogs implanted with DHT or E2 for 10 days did not show significant alterations in the HPG axis. In contrast, frogs implanted with hormones for 30 days had significantly lower circulating LH (for both DHT and E2), decreased pituitary LH concentration (for E2 only), and disrupted spermatogenesis (for both DHT and E2). The disruption of spermatogenesis was qualitatively similar between DHT and E2, although the effects of E2 were consistently more potent. In both DHT and E2-treated animals, a marked loss of all pre-meiotic germ cells was observed, although the loss of secondary spermatogonia appeared to be the primary cause of disrupted spermatogenesis. Unexpectedly, the presence of post-meiotic germ cells was either unaffected or enhanced by DHT or E2 treatment. CONCLUSIONS Overall, these results showed that both DHT and E2 inhibited circulating LH and disrupted spermatogenesis progressively in a time-dependent manner, with the longer duration of treatment producing the more pronounced effects. Further, the feedback effects exerted by both steroid hormones upon the HPG axis were largely negative, although the possibility exists for a stimulatory effect upon the post-meiotic germ cells.
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Affiliation(s)
- Pei-San Tsai
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
| | - Ann E Kessler
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
| | - Jeremy T Jones
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
| | - Kathleen B Wahr
- Department of Integrative Physiology and the Center for Neuroscience, University of Colorado, Boulder, CO 80309-0354, USA
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Abstract
In Bufo arenarum, androgen biosynthesis occurs through a complete 5-ene pathway, including 5-androstane-3beta,17beta-diol as the immediate precursor of testosterone. Besides, steroidogenesis changes during the breeding period, turning from androgens to C(21)-steroids such as 5alpha-pregnan-3alpha,20alpha-diol, 3alpha-hydroxy-5alpha-pregnan-20-one and 5alpha-pregnan-3,20-dione. In B. arenarum, steroid hormones are not involved in hCG-induced spermiation, suggesting that the steroidogenic shift to C(21)-steroids during the breeding be not related to spermiation. The activity of 17-hydroxylase-C(17-20) lyase (CypP450(c17)) decreases during the reproductive season, suggesting that this enzyme would represent a key enzyme in the regulation of seasonal changes. However, the increase in the affinity for pregnenolone of 3beta-hydroxysteroid dehydrogenase (3alphaHSD)/isomerase could also be involved. Moreover, the reduction in CypP450(c17) leading to a reduction in C(19)-steroids, among them dehydroepiandrosterone (DHE), would contribute to the conversion of pregnenolone into progesterone, avoiding the non-competitive inhibition exerted by DHE on this transformation. Additionally, CypP450(c17) possesses a higher affinity for pregnenolone than for progesterone, explaining the predominance of the 5-ene pathway for testosterone biosynthesis. Animals in reproductive condition showed a significant reduction in circulating androgens, enhancing the physiological relevance of all the in vitro results. The in vitro effects of mGnRH and hrFSH on testicular steroidogenesis revealed that both hormones inhibited CypP450(c17) activity. In summary, these results demonstrate that, in B. arenarum, the change in testicular steroidogenesis during the reproductive period could be partially due to an FSH and GnRH-induced decrease in CypP450(c17) activity.
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Affiliation(s)
- Luis F Canosa
- PRHOM-CONICET and Laboratorio de Endocrinología Comparada, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
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Pierantoni R, Cobellis G, Meccariello R, Fasano S. Evolutionary aspects of cellular communication in the vertebrate hypothalamo-hypophysio-gonadal axis. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 218:69-141. [PMID: 12199520 DOI: 10.1016/s0074-7696(02)18012-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This review emphasizes the comparative approach for developing insight into knowledge related to cellular communications occurring in the hypothalamus-pituitary-gonadal axis. Indeed, research on adaptive phenomena leads to evolutionary tracks. Thus, going through recent results, we suggest that pheromonal communication precedes local communication which, in turn, precedes communication via the blood stream. Furthermore, the use of different routes of communication by a certain mediator leads to a conceptual change related to what hormones are. Nevertheless, endocrine communication should leave out of consideration the source (glandular or not) of mediator. Finally, we point out that the use of lower vertebrate animal models is fundamental to understanding general physiological mechanisms. In fact, different anatomical organization permits access to tissues not readily approachable in mammals.
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Cobellis G, Meccariello R, Minucci S, Palmiero C, Pierantoni R, Fasano S. Cytoplasmic versus nuclear localization of Fos-related proteins in the frog, Rana esculenta, testis: in vivo and direct in vitro effect of a gonadotropin-releasing hormone agonist. Biol Reprod 2003; 68:954-60. [PMID: 12604648 DOI: 10.1095/biolreprod.102.008938] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Evidence has been accumulated indicating that GnRH-like peptides are present in a variety of extrabrain areas of mammalian and nonmammalian vertebrates. A pioneer study carried out in the frog, Rana esculenta, demonstrated that testicular GnRH induced spermatogonial proliferation. Recently, we have shown that in proliferating spermatogonia (SPG) of frogs, a change of localization of the oncoprotein Fos, from the cytoplasm to the nucleus, occurs. This leads to the hypothesis that one or more testicular GnRH peptides may regulate SPG proliferation through Fos family proteins. Therefore, in vivo experiments in intact R. esculenta and in vitro incubations of testis fragments have been carried out using GnRH agonist (GnRHa; buserelin) and GnRH antagonist (D-pGlu(1),D-Phe(2),D-Trp(3,6)-GnRH). Cytoplasmic and nuclear Fos-like protein localization has been found by Western blot analysis in testicular extracts. Immunocytochemistry confirmed that cytoplasmic immunostaining was restricted to SPG; change of localization into the nuclear compartment was observed after GnRHa treatment. Northern blot analysis showed that treatments of testis fragments with GnRHa did not modify testicular c-fos mRNA expression. On the contrary, a Fos-like protein of 52 kDa, while not affected in vivo, disappeared from testicular cytosolic extracts after in vitro treatment with GnRHa. Contemporaneously, a 55-kDa Fos-related signal appeared in nuclear extracts. The GnRH antagonist counteracted the effects of GnRHa. Furthermore, in vivo treatments showed that GnRHa acted negatively on a 43-kDa nuclear Fos-related signal and that gonadotropins caused the decrease of 52-kDa cytoplasmic signal. In conclusion, we show, to our knowledge for the first time, that Fos is regulated by GnRHa directly (not through the pituitary) at the testicular level. The main effect appears to be related to Fos translocation from cytoplasmic to nuclear compartments of SPG.
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Affiliation(s)
- Gilda Cobellis
- Dipartimento di Medicina Sperimentale, sez. "F. Bottazzi," 80138 Napoli, Italy
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17
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Canosa LF, Pozzi AG, Somoza GM, Ceballos NR. Effects of mGnRH on testicular steroidogenesis in the toad Bufo arenarum. Gen Comp Endocrinol 2002; 127:174-80. [PMID: 12383445 DOI: 10.1016/s0016-6480(02)00044-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
GnRH controls vertebrate reproduction in several ways. This hormone not only affects the secretion of gonadotropins from the pituitary gland but also has a direct influence on several gonadal functions such as steroidogenesis, spermatogenesis, and spermiation. In the present paper we have studied the in vitro effects of GnRH on the testicular steroidogenesis of Bufo arenarum to ascertain the role of this peptide in the control of the steroidogenic pathway previously described in this species. It was found that GnRH is able to reduce basal as well as hCG-stimulated testosterone release, having an inhibitory effect on P450(c17) activity. Thus, GnRH could be involved in the mechanism that regulates the metabolic change in the testicular steroidogenesis. Additionally, testicular GnRH binding site has been characterised, showing a K(d) of 34 nM and a maximum binding of 4.7 pmol/mg protein.
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Affiliation(s)
- Luis F Canosa
- Laboratorio de Endocrinología Comparada, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales and PRHOM-CONICET, Pabellón 2, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
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18
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Hislop JN, Everest HM, Flynn A, Harding T, Uney JB, Troskie BE, Millar RP, McArdle CA. Differential internalization of mammalian and non-mammalian gonadotropin-releasing hormone receptors. Uncoupling of dynamin-dependent internalization from mitogen-activated protein kinase signaling. J Biol Chem 2001; 276:39685-94. [PMID: 11495905 DOI: 10.1074/jbc.m104542200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Desensitization and internalization of G-protein-coupled receptors can reflect receptor phosphorylation-dependent binding of beta-arrestin, which prevents G-protein activation and targets receptors for internalization via clathrin-coated vesicles. These can be pinched off by a dynamin collar, and proteins controlling receptor internalization can also mediate mitogen-activated protein kinase signaling. Gonadotropin-releasing hormone (GnRH) stimulates internalization of its receptors via clathrin-coated vesicles. Mammalian GnRH receptors (GnRH-Rs) are unique in that they lack C-terminal tails and do not rapidly desensitize, whereas non-mammalian GnRH-R have C-terminal tails and, where investigated, do rapidly desensitize and internalize. Using recombinant adenovirus expressing human and Xenopus GnRH-Rs we have explored the relationship between receptor internalization and mitogen-activated protein kinase signaling in HeLa cells with regulated tetracycline-controlled expression of wild-type or a dominant negative mutant (K44A) of dynamin. These receptors were phospholipase C-coupled and had appropriate ligand affinity and specificity. K44A dynamin expression did not alter human GnRH-R internalization but dramatically reduced internalization of Xenopus GnRH-R (and epidermal growth factor (EGF) receptor). Blockade of clathrin-mediated internalization (sucrose) abolished internalization of all three receptors. Both GnRH-Rs also mediated phosphorylation of ERK 2 and for both receptors, this was inhibited by K44A dynamin. The same was true for EGF- and protein kinase C-mediated ERK 2 phosphorylation. ERK 2 phosphorylation was also inhibited by a protein kinase C inhibitor but not affected by an EGF receptor tyrosine kinase inhibitor. We conclude that a) desensitizing and non-desensitizing GnRH-Rs are targeted for clathrin-coated vesicle-mediated internalization by functionally distinct mechanisms, b) GnRH-R signaling to ERK 2 is dynamin-dependent and c) this does not reflect a dependence on dynamin-dependent GnRH-R internalization.
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Affiliation(s)
- J N Hislop
- University Research Centre for Neuroendocrinology, University of Bristol, Bristol, BS2 8HW, United Kingdom
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19
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Troskie BE, Hapgood JP, Millar RP, Illing N. Complementary deoxyribonucleic acid cloning, gene expression, and ligand selectivity of a novel gonadotropin-releasing hormone receptor expressed in the pituitary and midbrain of Xenopus laevis. Endocrinology 2000; 141:1764-71. [PMID: 10803587 DOI: 10.1210/endo.141.5.7453] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have cloned the full-length complementary DNA (cDNA) for a GnRH receptor from Xenopus laevis pituitary cDNA and determined its gene structure. The cDNA encodes a 368-amino acid protein that has a 46% amino acid identity to the human GnRH receptor. The X laevis GnRH receptor has all of the amino acids identified in the mammalian GnRH receptors as sites of interaction with the GnRH ligand. However, this receptor cDNA shares the same distinguishing structural features of the GnRH receptor that have been characterized from other nonmammalian vertebrates. These include the pair of aspartate residues in the transmembrane domains II and VII compared with the aspartate/asparagine arrangement in mammalian receptors, the amino acid PEY motif in extracellular loop III (SEP in mammals), and the presence of a carboxyl-terminal tail. Previous studies have reported that mammalian GnRH was equipotent to other naturally occurring GnRH subtypes in stimulating LH release from the amphibian pituitary. However, in this study we show that the X. laevis GnRH receptor has ligand selectivity for the naturally occurring GnRHs similar to other nonmammalian GnRH receptors. The order of potency of the GnRHs in stimulating inositol phosphate production in COS-1 cells transiently transfected with the X. laevis GnRH receptor cDNA was chicken GnRH II>salmon GnRH>mammalian GnRH. Transcripts of this GnRH receptor are expressed in the pituitary and midbrain of X. laevis.
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Affiliation(s)
- B E Troskie
- Department of Medical Biochemistry, University of Cape Town, Observatory, South Africa.
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20
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Fasano S, Chieffi P, Cobellis G, Pierantoni R. Neuroendocrine and local control of the frog testis. Ann N Y Acad Sci 1998; 839:260-4. [PMID: 9629162 DOI: 10.1111/j.1749-6632.1998.tb10771.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S Fasano
- Department of Human Physiology and Integrative Biology Filippo Bottazzi II, University of Naples, Italy
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21
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Gnessi L, Fabbri A, Spera G. Gonadal peptides as mediators of development and functional control of the testis: an integrated system with hormones and local environment. Endocr Rev 1997; 18:541-609. [PMID: 9267764 DOI: 10.1210/edrv.18.4.0310] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- L Gnessi
- Dipartimento di Fisiopatologia Medica, Università di Roma La Sapienza, Italy
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22
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Battisti A, Pierantoni R, Vallarino M, Trabucchi M, Carnevali O, Polzonetti-Magni AM, Fasano S. Detection of GnRH molecular forms in brains and gonads of the crested newt, Triturus carnifex. Peptides 1997; 18:1029-37. [PMID: 9357062 DOI: 10.1016/s0196-9781(97)00024-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gonadotrophin-releasing hormone (GnRH) immunoreactivity is detectable in the brain, ovary, and testis of the newt, Triturus carnifex, collected during February (reproductive phase), May, and July (nonreproductive phase). In the brain of May animals, chicken GnRH-II positive cell bodies are located within the terminal nerve, the anterior preoptic area, and the preoptic nucleus, which appears to be devoid of immunoreactive mammalian GnRH cell bodies. During February and July, both chicken GnRH-II and mammalian GnRH are detected only within the terminal nerve and anterior preoptic area. Generally, in the reproductive as well as the nonreproductive periods, chicken GnRH-II fibers are widely distributed in the brain; however, the distribution of fibers of both molecular forms suggests that they exert hypophysiotropic activity. High-pressure liquid chromatography (HPLC) coupled with radioimmunoassay indicates the presence of an early-eluting GnRH peak in brains and gonads but not in plasma. Using chicken GnRH-II antiserum, immunoreactivity is observed in spermatocytes, spermatozoa, and the external theca layer. Seasonal changes of the GnRH-like material are observed in both sexes, and its high concentration detectable during February is in good correlation with the timing of reproduction.
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Affiliation(s)
- A Battisti
- Dipartimento di Biologia MCA, Università di Camerino, Italy
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King JA, Millar RP, Vallarino M, Pierantoni R. Localization and characterization of gonadotropin-releasing hormones in the brain, gonads, and plasma of a dipnoi (lungfish, Protopterus annectens). REGULATORY PEPTIDES 1995; 57:163-74. [PMID: 7659791 DOI: 10.1016/0167-0115(95)00025-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Two molecular forms of GnRH (chicken GnRH II and a second variant) are present in the brains of species from all the major vertebrate groups. Their differential distribution in the brain and temporal expression during development suggests that have different functional roles. We investigated the nature of GnRH molecular forms in the brain, plasma, testis, and ovary of adult and juvenile lungfish (Protopterus annectens), using high performance liquid chromatography and radioimmunoassay with specific GnRH antisera. In the brain of adult and juvenile lungfish, two peptides with identical chromatographic and immunologic properties to mammalian GnRH and chicken GnRH II were detected. Chicken GnRH II predominated in both the adult and juvenile brain, and the percentage of chicken GnRH II relative to mammalian GnRH was greater in the juvenile brain. In the plasma, only mammalian GnRH was present. Immunoreactive GnRH was not detected in the testis and ovary. Chicken GnRH II and mammalian GnRH were found in the cells of the preoptic nucleus and in the ganglion of the nervus terminalis. Fibers were seen in the ventral hypothalamus, and chicken GnRH II immunoreactivity was detected within the neural lobe of the pituitary. The finding of chicken GnRH II in a sarcopterygian fish adds further support to our hypothesis that this ubiquitous structural variant is highly conserved and likely to have an important functional role. Mammalian GnRH, previously described in several early-evolved actinopterygian fish, also has a fairly widespread distribution and early evolutionary origin. The immunocytochemical distribution of mammalian GnRH and chicken GnRH II fibers in the lungfish brain suggests that both forms are hypophysiotropic. In addition, the presence of mammalian GnRH in the plasma of the lungfish suggests that this molecular form of GnRH has a hypophysiotropic function reaching target organs (pituitary and gonads) via the general circulation.
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Affiliation(s)
- J A King
- Department of Chemical Pathology, University of Cape Town Medical School, South Africa
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24
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Pati D, Habibi HR. Gonadotropin-releasing hormone (GnRH) binding characteristics in the testis of goldfish (Carassius auratus). ACTA ACUST UNITED AC 1993. [DOI: 10.1002/jez.1402670208] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Fasano S, Goos HJ, Janssen C, Pierantoni R. Two GnRHs fluctuate in correlation with androgen levels in the male frog Rana esculenta. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1993; 266:277-83. [PMID: 8354991 DOI: 10.1002/jez.1402660405] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
ChickenII-(cII-) and salmon (s-) GnRH levels have been measured in the male frog Rana esculenta during the annual cycle. The presence of pituitary binding activity for both peptides and plasma androgen levels has been investigated in order to give insight into the significance of the dual control exerted by the GnRH forms present in the R. esculenta brain. ChickenII- and s-GnRHs showed high values during the spring-summer period. Conversely, while cII-GnRH peaked in February, s-GnRH declined slowly from February until May. Plasma androgen levels increased as the peptides decreased during the autumn-winter period. Still high androgen levels (but significantly lower as compared with winter concentrations) were found during spring. Using iodinated cII-GnRH, GnRH binding sites were detected in pituitary preparations when the corresponding peptide concentration decreased in the brain. On the contrary, no binding sites were found using labeled s-GnRH. Our results indicate that cII-GnRH has a hypophysiotropic activity, while the role of s-GnRH needs to be further investigated.
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Affiliation(s)
- S Fasano
- Dipartimento di Fisiologia Umana e Funzioni Biologiche Integrate F. Bottazzi II Università di Napoli, Italy
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26
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D'Antonio M, Fasano S, de Leeuw R, Pierantoni R. Effects of gonadotropin-releasing hormone variants on plasma and testicular androgen levels in intact and hypophysectomized male frogs, Rana esculenta. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1992; 261:34-9. [PMID: 1729384 DOI: 10.1002/jez.1402610106] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects of vertebrate gonadotropin-releasing hormone (GnRH) variants on plasma and testicular androgen level in intact and hypophysectomized (PDX) male frogs, Rana esculenta, have been investigated. In intact animals, mammalian (m)-GnRH, m-GnRH analog (buserelin), salmon (s)-GnRH, chicken (c) I-GnRH, cII-GnRH, D-Arg6-cII-GnRH (cII-GnRHA), and lamprey (l)-GnRH (1.5 micrograms and 6 micrograms, total dose given on alternate days for 5 days) were able to enhance androgen production showing that specificity of pituitary responsiveness to GnRH variants appears to be low. Chicken II-GnRH was more effective than s-GnRH in eliciting testicular and circulatory androgen level increase. Moreover, in animals treated with 6 micrograms of cII-GnRH and s-GnRH in combination, androgens decreased as compared with animal treated with cII-GnRH only, suggesting that GnRH receptors bind preferentially the s-GnRH form. In PDX animals, buserelin (1.5 and 6 micrograms), cII-GnRH, and its analog (6 micrograms) were able to increase plasma androgen levels whereas testis androgen concentrations were increased by cII-GnRH (1.5 and 6 micrograms), D-Arg6-cII-GnRHA, and buserelin (6 micrograms). Since androgen production in PDX animals is influenced especially by peptides sharing cII-GnRH structure, it is suggested that a testicular cII-GnRH-like material play a role as local modulator of the gonadal activity in Rana esculenta.
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Affiliation(s)
- M D'Antonio
- Dipartimento di Fisiologia Umana e Funzioni Biologiche Integrate Filippo Bottazzi, I Facoltà di Medicina e Chirurgia, Naples, Italy
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27
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Chieffi G, Pierantoni R, Fasano S. Immunoreactive GnRH in hypothalamic and extrahypothalamic areas. INTERNATIONAL REVIEW OF CYTOLOGY 1991; 127:1-55. [PMID: 1652571 DOI: 10.1016/s0074-7696(08)60691-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- G Chieffi
- Dipartimento di Fisiologia Umana, Filippo Bottazzi Università di Napoli, Italy
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