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Toledo J, Perez PA, Zanetti M, Díaz-Torga G, Mukdsi JH, Gutierrez S. FLNA expression modulates pathological markers of pituitary neuroendocrine tumours. J Endocrinol 2024; 260:e230209. [PMID: 37855268 DOI: 10.1530/joe-23-0209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 10/19/2023] [Indexed: 10/20/2023]
Abstract
Due to the current limited knowledge about the role of filamin A (FLNA) in pituitary tumour progression, we aimed to analyse FLNA expression levels and its impact on aggressive markers of pituitary neuroendocrine tumours (PitNETs), using an integrative approach of in vivo and in vitro models and human samples. An increase in the expression levels of FLNA was observed in the advanced tumoural stages of the hyperplastic adenomatous pituitary model, concomitant with a decrease in cell proliferation and with a modification in the subcellular localisation of this protein. Similarly, overexpression of FLNA in the somatolactotropic GH3 cell line induced a decrease in the cell proliferation, promoted a migratory phenotype, increased invasion activity, and decreased the prolactin secretion. Cyclin D1 (CCND1) and cyclin-dependent kinase 4 (CDK4) expression increased in both models in correlation with the increase observed in FLNA levels. When human tissues were analysed a significant increase of FLNA was observed in PitNETs compared to normal pituitary gland, with heterogeneous intracellular localisation. Higher levels of FLNA expression were observed in tumours with invasive characteristics. These results underline the crucial roles of FLNA as a modulator of pathological markers and as a potential prognostic marker in pituitary tumours.
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Affiliation(s)
- Jonathan Toledo
- Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Córdoba, Argentina
- Centro de Microscopia Electrónica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Pablo Aníbal Perez
- Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Córdoba, Argentina
- Centro de Microscopia Electrónica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Mical Zanetti
- Centro de Microscopia Electrónica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
| | - Jorge Humberto Mukdsi
- Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Córdoba, Argentina
- Centro de Microscopia Electrónica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Silvina Gutierrez
- Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Córdoba, Argentina
- Centro de Microscopia Electrónica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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Abeledo-Machado A, Peña-Zanoni M, Bornancini D, Díaz-Torga G. Revealing Sexual Dimorphism in Prolactin Regulation From Early Postnatal Development to Adulthood in Murine Models. J Endocr Soc 2023; 8:bvad146. [PMID: 38045876 PMCID: PMC10690727 DOI: 10.1210/jendso/bvad146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Indexed: 12/05/2023] Open
Abstract
Serum prolactin (PRL) levels exhibit a gradual rise both in male and female rats from birth to adulthood, with females consistently displaying higher levels compared to age-matched males. This pattern has traditionally been attributed to the development and maturation of endocrine and neuroendocrine networks responsible for regulating PRL synthesis and secretion. However, the effect of dopamine (DA), which acts as an inhibitory factor on lactotroph function, also increases from birth to puberty, particularly in females. Nonetheless, the secretion of PRL remains higher in females compared to males. On the other hand, the observed sex differences in serum PRL levels during early postnatal development cannot be attributed to the influence of estradiol (E2). While serum E2 levels gradually increase after birth, only after 45 days of life do the disparities in E2 levels between females and males become evident. These observations collectively suggest that neither the maturation of hypothalamic DA regulation nor the rise in E2 levels can account for the progressive and sustained elevation in serum PRL levels and the observed sexual dimorphism during postnatal development. This review highlights the importance of recent discoveries in animal models that shed light on inhibitory mechanisms in the control of PRL secretion within the pituitary gland itself, that is intrapituitary mechanisms, with a specific emphasis on the role of transforming growth factor β1 and activins in PRL secretion.
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Affiliation(s)
- Alejandra Abeledo-Machado
- Instituto de Biología y Medicina Experimental (IBYME), Fundación IBYME, CONICET, Buenos Aires 1428, Argentina
| | - Milagros Peña-Zanoni
- Instituto de Biología y Medicina Experimental (IBYME), Fundación IBYME, CONICET, Buenos Aires 1428, Argentina
| | - Dana Bornancini
- Instituto de Biología y Medicina Experimental (IBYME), Fundación IBYME, CONICET, Buenos Aires 1428, Argentina
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), Fundación IBYME, CONICET, Buenos Aires 1428, Argentina
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3
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Abeledo-Machado A, Bornancini D, Peña-Zanoni M, Camilletti MA, Faraoni EY, Díaz-Torga G. Sex-specific regulation of prolactin secretion by pituitary activins in postnatal development. J Endocrinol 2023; 258:e230020. [PMID: 37399522 DOI: 10.1530/joe-23-0020] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 07/03/2023] [Indexed: 07/05/2023]
Abstract
Serum prolactin increases from birth to adulthood in rats, being higher in females from birth. The maturation of hypothalamic/gonadal prolactin-releasing and -inhibiting factors does not explain some sex differences observed. During the first weeks of life, prolactin secretion increases, even when lactotrophs are isolated in vitro, in the absence of those controls, suggesting the participation of intra-pituitary factors in this control. The present work aimed to study the involvement of pituitary activins in the regulation of prolactin secretion during post-natal development. Sex differences were also highlighted. Female and male Sprague-Dawley rats at 11, 23 and 45postnatal days were used. Pituitary expression of activin subunits and activin receptors was maximum in p11 female pituitaries, being even higher than that observed in males. Those expressions decrease with age in females, and then the gender differences disappear at p23. Inhbb expression strongly increases at p45 in males, being the predominant subunit in this sex in adulthood. Activin inhibition of prolactin is mediated by the inhibition of Pit-1 expression. This action involves not only the canonical pSMAD pathway but also the phosphorylation of p38MAPK. At p11, almost all lactotrophs express p-p38MAPK in females, and its expression decreases with age with a concomitant increase in Pit-1. Our findings suggest that the inhibitory regulation of pituitary activins on prolactin secretion is sex specific; this regulation is more relevant in females during the first week of life and decreases with age; this intra-pituitary regulation is involved in the sex differences observed in serum prolactin levels during postnatal development.
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Affiliation(s)
| | - Dana Bornancini
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Milagros Peña-Zanoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | | | - Erika Yanil Faraoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
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4
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Sabatino ME, Díaz-Torga G, De Paul AL. Editorial: Architects of Endocrine-Related Tumour Growth. Front Endocrinol (Lausanne) 2022; 13:1046478. [PMID: 36353237 PMCID: PMC9638145 DOI: 10.3389/fendo.2022.1046478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 09/23/2022] [Indexed: 11/18/2022] Open
Affiliation(s)
- María Eugenia Sabatino
- Instituto de Ciencia y Tecnología de Alimentos Córdoba -Consejo Nacional de Investigaciones Científicas y Técnicas (ICyTAC-CONICET), Córdoba, Argentina
- *Correspondence: María Eugenia Sabatino,
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Ana Lucía De Paul
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigación en Ciencias de la Salud (INICSA), Córdoba, Argentina
- Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Centro de Microscopía Electrónica, Córdoba, Argentina
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5
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Faraoni EY, Abeledo Machado AI, Pérez PA, Marcial López CA, Camilletti MA, Peña-Zanoni M, Rulli SB, Gutiérrez S, Díaz-Torga G. Activin-inhibitory action on lactotrophs is decreased in lactotroph hyperplasia. J Endocrinol 2020; 244:415-429. [PMID: 32395971 DOI: 10.1530/joe-19-0326] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/16/2019] [Indexed: 11/08/2022]
Abstract
Among all the hormone-secreting pituitary tumours, prolactinomas are the most frequently found in the clinic. Since dopamine is the primary inhibitor of lactotroph function, dopamine agonists represent the first-line therapy. However, a subset of patients exhibits resistance to these drugs, and therefore, alternative treatments are desired. As activins inhibit prolactin gene expression through the inhibition of Pit-1 involving the p38MAPK pathway, in the present work, we studied the local activin system as an alternative inhibitory system for lactotroph hyperplasia treatment. We used two different mouse models of prolactinoma: transgenic mice with overexpression of the human chorionic gonadotropin β-subunit (hCGβ) and mice lacking dopamine receptor type 2. In both models, females, but not males, develop lactotroph hyperplasia from the fourth month of life. We found reduced expression of pituitary activin subunits and activin receptors in hyperplastic pituitaries from both models compared with wild-type counterparts. Consequently, hyperplastic pituitaries presented a reduced activin-inhibitory action on prolactin secretion. Additionally, while female wild-type lactotrophs presented high levels of phospho-p38MAPK, it was lost in prolactinomas, concomitant with decreased activin expression, increased Pit-1 expression and tumour development. In contrast, male pituitaries express higher mRNA levels of activin subunits βA and βB, which would suggest a stronger activin inhibitory function on lactotrophs, protecting this sex from tumour development, despite genotype. The present results highlight the importance of the activin inhibitory action on lactotroph function and place the local activin system as a new target for the treatment of dopamine agonist-resistant prolactinomas.
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Affiliation(s)
- E Y Faraoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - A I Abeledo Machado
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - P A Pérez
- Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - C A Marcial López
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - M A Camilletti
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - M Peña-Zanoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - S B Rulli
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - S Gutiérrez
- Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - G Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
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Camilletti MA, Abeledo-Machado A, Faraoni EY, Thomas P, Díaz-Torga G. New insights into progesterone actions on prolactin secretion and prolactinoma development. Steroids 2019; 152:108496. [PMID: 31521709 DOI: 10.1016/j.steroids.2019.108496] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/05/2019] [Accepted: 09/09/2019] [Indexed: 12/12/2022]
Abstract
Progesterone (P4) has controversial physiological effects on the regulation of the lactotroph population. While some studies have shown a negative role for P4 in prolactin secretion and lactotroph proliferation, antagonizing estradiol effects, others demonstrated a proliferative role of P4 at the pituitary level. Usually, progesterone actions in the pituitary gland were studied through their classical, genomic pathways triggered by nuclear progesterone receptors (nPRs). However, in 2003, the scene became more complex with the discovery of another group of progesterone receptors involved in rapid, non-genomic P4 effects: the membrane progesterone receptors (mPRs), which are members of the progesterone and adipoQ receptor (PAQR) family. This review examines the historical background and current data on the study of progesterone actions on PRL secretion providing new evidence of P4 effects at the hypothalamic and at the pituitary level through non-classic P4-receptors. In addition, we explore the role of progesterone in the development of experimental prolactinomas, a controversial topic in the literature.
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Affiliation(s)
- María A Camilletti
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | | | - Erika Y Faraoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Peter Thomas
- Marine Science Institute, University of Texas at Austin, Port Aransas, TX, USA
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina.
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7
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Camilletti MA, Abeledo-Machado A, Perez PA, Faraoni EY, De Fino F, Rulli SB, Ferraris J, Pisera D, Gutierrez S, Thomas P, Díaz-Torga G. mPRs represent a novel target for PRL inhibition in experimental prolactinomas. Endocr Relat Cancer 2019; 26:497-510. [PMID: 30856609 DOI: 10.1530/erc-18-0409] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 03/11/2019] [Indexed: 12/15/2022]
Abstract
Membrane progesterone receptors are known to mediate rapid nongenomic progesterone effects in different cell types. Recent evidence revealed that mPRα is highly expressed in the rat pituitary, being primarily localized in lactotrophs, acting as an intermediary of P4-inhibitory actions on prolactin secretion. The role of mPRs in prolactinoma development remains unclear. We hypothesize that mPR agonists represent a novel tool for hyperprolactinemia treatment. To this end, pituitary expression of mPRs was studied in three animal models of prolactinoma. Expression of mPRs and nuclear receptor was significantly decreased in tumoral pituitaries compared to normal ones. However, the relative proportion of mPRα and mPRβ was highly increased in prolactinomas. Interestingly, the selective mPR agonist (Org OD 02-0) significantly inhibited PRL release in both normal and tumoral pituitary explants, displaying a more pronounced effect in tumoral tissues. As P4 also regulates PRL secretion indirectly, by acting on dopaminergic neurons, we studied mPR involvement in this effect. We found that the hypothalamus has a high expression of mPRs. Interestingly, both P4 and OrgOD 02-0 increased dopamine release in hypothalamus explants. Moreover, in an in vivo treatment, that allows both, pituitary and hypothalamus actions, the mPR agonist strongly reduced the hyperprolactinemia in transgenic females carrying prolactinoma. Finally, we also found and interesting gender difference: males express higher levels of pituitary mPRα/β, a sex that does not develop prolactinoma in these mice models. Taken together, these findings suggest mPRs activation could represent a novel tool for hyperprolactinemic patients, especially those that present resistance to dopaminergic drugs.
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Affiliation(s)
| | | | - Pablo A Perez
- Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Erika Y Faraoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Fernanda De Fino
- Instituto de Investigaciones Farmacológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Susana B Rulli
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Jimena Ferraris
- Instituto de Investigaciones Biomédicas (INBIOMED), Facultad de Medicina, UBA-CONICET, Buenos Aires, Argentina
| | - Daniel Pisera
- Instituto de Investigaciones Biomédicas (INBIOMED), Facultad de Medicina, UBA-CONICET, Buenos Aires, Argentina
| | - Silvina Gutierrez
- Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Peter Thomas
- Marine Science Institute, University of Texas at Austin, Port Aransas, Texas, USA
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
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8
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Camilletti MA, Abeledo-Machado A, Ferraris J, Pérez PA, Faraoni EY, Pisera D, Gutierrez S, Díaz-Torga G. Role of GPER in the anterior pituitary gland focusing on lactotroph function. J Endocrinol 2019; 240:99-110. [PMID: 30400046 DOI: 10.1530/joe-18-0402] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 10/19/2018] [Indexed: 12/22/2022]
Abstract
Ovarian steroids control a variety of physiological functions. They exert actions through classical nuclear steroid receptors, but rapid non-genomic actions through specific membrane steroid receptors have been also described. In this study, we demonstrate that the G-protein-coupled estrogen receptor (GPER) is expressed in the rat pituitary gland and, at a high level, in the lactotroph population. Our results revealed that ~40% of the anterior pituitary cells are GPER positive and ~35% of the lactotrophs are GPER positive. By immunocytochemical and immuno-electron-microscopy studies, we demonstrated that GPER is localized in the plasmatic membrane but is also associated to the endoplasmic reticulum in rat lactotrophs. Moreover, we found that local Gper expression is regulated negatively by 17β-estradiol (E2) and progesterone (P4) and fluctuates during the estrus cycle, being minimal in proestrus. Interestingly, lack of ovarian steroids after an ovariectomy (OVX) significantly increased pituitary GPER expression specifically in the three morphologically different subtypes of lactotrophs. We found a rapid estradiol stimulatory effect on PRL secretion mediated by GPER, both in vitro and ex vivo, using a GPER agonist G1, and this effect was prevented by the GPER antagonist G36, demonstrating a novel role for this receptor. Then, the increased pituitary GPER expression after OVX could lead to alterations in the pituitary function as all three lactotroph subtypes are target of GPER ligand and could be involved in the PRL secretion mediated by GPER. Therefore, it should be taken into consideration in the response of the gland to an eventual hormone replacement therapy.
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Affiliation(s)
- María Andrea Camilletti
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Alejandra Abeledo-Machado
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Jimena Ferraris
- Instituto de Investigaciones Biomédicas, Facultad de Medicina, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Pablo A Pérez
- Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Facultad de Ciencias Medicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Erika Y Faraoni
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Daniel Pisera
- Instituto de Investigaciones Biomédicas, Facultad de Medicina, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Silvina Gutierrez
- Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Facultad de Ciencias Medicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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9
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Camilletti MA, Ferraris J, Abeledo-Machado A, Converse A, Faraoni EY, Pisera D, Gutierrez S, Thomas P, Díaz-Torga G. Participation of membrane progesterone receptor α in the inhibitory effect of progesterone on prolactin secretion. J Neuroendocrinol 2018; 30:e12614. [PMID: 29869822 DOI: 10.1111/jne.12614] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/28/2018] [Accepted: 06/01/2018] [Indexed: 12/22/2022]
Abstract
The membrane progesterone receptors (mPRα, mPRβ, mPRγ, mPRδ and mPRε) are known to mediate rapid nongenomic progesterone functions in different cell types. However, the functions of these receptors in the pituitary have not been reported to date. In the present study, we show that the expression of mPRα was the highest among the mPRs in the rat anterior pituitary gland. Immunostaining of mPRα was detected in somatotrophs, gonadotrophs and lactotrophs. Interestingly, 63% of mPRα-positive cells within the pituitary were lactotrophs, suggesting that mPRα is involved in controlling prolactin (PRL) secretion in the pituitary. To test this hypothesis, rat pituitaries were incubated (1 hour) with either progesterone (P4) or the mPRα-specific agonist Org OD 02-0. PRL secretion was then measured by radioimmunoassay. The results of this experiment revealed that both P4 and Org OD 02-0 decreased PRL secretion. Moreover, the results from the GH3 cell line (CCL-82.1) showed that P4 and Org OD 02-0 inhibited PRL release, although the nuclear PR agonist R5020 was ineffective. Our investigation of the cellular mechanisms behind mPRα activity indicated that both P4 and Org OD 02-0 decreased cAMP accumulation, whereas R5020 was ineffective. In addition, the Org OD 02-0-effect on PRL release was blocked by pretreatment with pertussis toxin, an inhibitor of Go/Gi proteins. Because transforming growth factor (TGF)β1 is a potent inhibitor of PRL secretion in lactotrophs, we lastly evaluated whether TGFβ1 was activated by progesterone and whether this effect was mediated by mPRα. Our results showed that P4 and Org OD 02-0, but not R5020, increased active TGFβ1 levels. This effect was not observed when cells were transfected with mPRα-small interfering RNA. Taken together, these data provide new evidence suggesting that mPRα mediates the progesterone inhibitory effect on PRL secretion through both decreases in cAMP levels and activation of TGFβ1 in the lactotroph population.
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Affiliation(s)
- M A Camilletti
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - J Ferraris
- Facultad de Medicina, Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Buenos Aires, Argentina
| | - A Abeledo-Machado
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - A Converse
- Marine Science Institute, University of Texas at Austin, Port Aransas, TX, USA
| | - E Y Faraoni
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - D Pisera
- Facultad de Medicina, Instituto de Investigaciones Biomédicas (INBIOMED), UBA-CONICET, Buenos Aires, Argentina
| | - S Gutierrez
- Facultad de Ciencias Medicas, Centro de Microscopia Electrónica, Instituto de Investigaciones en Ciencias de la Salud (INICSA-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - P Thomas
- Marine Science Institute, University of Texas at Austin, Port Aransas, TX, USA
| | - G Díaz-Torga
- Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
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10
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Recouvreux MV, Faraoni EY, Camilletti MA, Ratner L, Abeledo-Machado A, Rulli SB, Díaz-Torga G. Sex differences in the pituitary TGFβ1 system: The role of TGFβ1 in prolactinoma development. Front Neuroendocrinol 2018; 50:118-122. [PMID: 29074127 DOI: 10.1016/j.yfrne.2017.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/21/2017] [Accepted: 10/11/2017] [Indexed: 02/07/2023]
Abstract
Prolactinomas are the most frequent functioning pituitary adenomas, and sex differences in tumor size, behavior and incidence have been described. These differences have been associated with earlier diagnosis in woman, as well as with serum estradiol levels. Experimental models of prolactinomas in rodents also show a higher incidence in females, and recent findings suggest that gender differences in the transforming growth factor beta 1 (TGFβ1) system might be involved in the sex-specific development of prolactinomas in these models. The aim of this review is to summarize the literature supporting the important role of TGFβ1 as a local modulator of pituitary lactotroph function and to provide recent evidence for TGFβ1 involvement in the sex differences found in prolactinoma development in animal models.
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Affiliation(s)
- M Victoria Recouvreux
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina; Tumor Initiation and Maintenance Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla, CA 92037, United States.
| | - Erika Y Faraoni
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina.
| | - M Andrea Camilletti
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina.
| | - Laura Ratner
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina.
| | - Alejandra Abeledo-Machado
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina.
| | - Susana B Rulli
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina.
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina.
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11
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Faraoni EY, Camilletti MA, Abeledo-Machado A, Ratner LD, De Fino F, Huhtaniemi I, Rulli SB, Díaz-Torga G. Sex differences in the development of prolactinoma in mice overexpressing hCGβ: role of TGFβ1. J Endocrinol 2017; 232:535-546. [PMID: 28096433 DOI: 10.1530/joe-16-0371] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/17/2017] [Indexed: 01/15/2023]
Abstract
Female transgenic mice that overexpress the human chorionic gonadotrophin β subunit (hCGβ+) develop prolactinomas, whereas hCGβ+ males do not. The high levels of circulating hCG induce massive luteinization in the ovary of hCGβ+ females, and progesterone becomes the primary steroid hormone produced, but estradiol remains at physiological level. The involvement of high levels of progesterone in lactotroph proliferation is not clearly understood; hence, the pathogenesis of prolactinomas in hCGβ+ females remains unclear. TGFβ1 is an inhibitor of lactotroph function, and the reduced TGFβ1 activity found in prolactinomas has been proposed to be involved in tumor development. The aim of the present work was to study the role of TGFβ1 in the gender-specific development of prolactinomas in hCGβ+ mice. We compared the expression of different components of the pituitary TGFβ1 system in males and females in this model. We found reduced TGFβ1 levels, reduced expression of TGFβ1 target genes, TGFβ1 receptors, Ltbp1, Smad4 and Smad7 in hCGβ+ female pituitaries. However, no differences were found between the transgenic and wild-type male pituitaries. We postulate that decreased pituitary TGFβ1 activity in hCGβ+ females is involved in the development of prolactinomas. In fact, we demonstrated that an in vivo treatment carried out for increasing pituitary TGFβ1 activity, was successful in reducing the prolactinoma development, and the hyperprolactinemia in hCGβ+ females. Moreover, the stronger TGFβ1 system found in males could protect them from excessive lactotroph proliferation. Sex differences in the regulation of the pituitary TGFβ1 system could explain gender differences in the incidence of prolactinoma.
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Affiliation(s)
- Erika Y Faraoni
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - María Andrea Camilletti
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Alejandra Abeledo-Machado
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Laura D Ratner
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Fernanda De Fino
- Instituto de Investigaciones FarmacológicasConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Ilpo Huhtaniemi
- Department of Surgery & CancerInstitute of Reproductive and Developmental Biology, Imperial College London, London, UK
| | - Susana B Rulli
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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12
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Abstract
Prolactinomas are the most frequently observed pituitary adenomas and most of them respond well to conventional treatment with dopamine agonists (DAs). However, a subset of prolactinomas fails to respond to such therapies and is considered as DA-resistant prolactinomas (DARPs). New therapeutic approaches are necessary for these tumors. Transforming growth factor β1 (TGFβ1) is a known inhibitor of lactotroph cell proliferation and prolactin secretion, and it partly mediates dopamine inhibitory action. TGFβ1 is secreted to the extracellular matrix as an inactive latent complex, and its bioavailability is tightly regulated by different components of the TGFβ1 system including latent binding proteins, local activators (thrombospondin-1, matrix metalloproteases, integrins, among others), and TGFβ receptors. Pituitary TGFβ1 activity and the expression of different components of the TGFβ1 system are regulated by dopamine and estradiol. Prolactinomas (animal models and humans) present reduced TGFβ1 activity as well as reduced expression of several components of the TGFβ1 system. Therefore, restoration of TGFβ1 inhibitory activity represents a novel therapeutic approach to bypass dopamine action in DARPs. The aim of this review is to summarize the large literature supporting TGFβ1 important role as a local modulator of pituitary lactotroph function and to provide recent evidence of the restoration of TGFβ1 activity as an effective treatment in experimental prolactinomas.
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Affiliation(s)
- M Victoria Recouvreux
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428 Buenos Aires, ArgentinaDepartment of MedicineCedars Sinai Medical Center, Los Angeles, California 90048, USADepartment of Cell BiologyNew York University Medical Center, 550 First Avenue, New York, New York 10016, USA Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428 Buenos Aires, ArgentinaDepartment of MedicineCedars Sinai Medical Center, Los Angeles, California 90048, USADepartment of Cell BiologyNew York University Medical Center, 550 First Avenue, New York, New York 10016, USA
| | - M Andrea Camilletti
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428 Buenos Aires, ArgentinaDepartment of MedicineCedars Sinai Medical Center, Los Angeles, California 90048, USADepartment of Cell BiologyNew York University Medical Center, 550 First Avenue, New York, New York 10016, USA
| | - Daniel B Rifkin
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428 Buenos Aires, ArgentinaDepartment of MedicineCedars Sinai Medical Center, Los Angeles, California 90048, USADepartment of Cell BiologyNew York University Medical Center, 550 First Avenue, New York, New York 10016, USA
| | - Graciela Díaz-Torga
- Instituto de Biología y Medicina ExperimentalConsejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428 Buenos Aires, ArgentinaDepartment of MedicineCedars Sinai Medical Center, Los Angeles, California 90048, USADepartment of Cell BiologyNew York University Medical Center, 550 First Avenue, New York, New York 10016, USA
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13
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Recouvreux MV, Lapyckyj L, Camilletti MA, Guida MC, Ornstein A, Rifkin DB, Becu-Villalobos D, Díaz-Torga G. Sex differences in the pituitary transforming growth factor-β1 system: studies in a model of resistant prolactinomas. Endocrinology 2013; 154:4192-205. [PMID: 24008346 PMCID: PMC3800752 DOI: 10.1210/en.2013-1433] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 08/27/2013] [Indexed: 12/29/2022]
Abstract
Dopamine and estradiol interact in the regulation of lactotroph cell proliferation and prolactin secretion. Ablation of the dopamine D2 receptor gene (Drd2(-/-)) in mice leads to a sexually dimorphic phenotype of hyperprolactinemia and pituitary hyperplasia, which is stronger in females. TGF-β1 is a known inhibitor of lactotroph proliferation. TGF-β1 is regulated by dopamine and estradiol, and it is usually down-regulated in prolactinoma experimental models. To understand the role of TGF-β1 in the gender-specific development of prolactinomas in Drd2(-/-) mice, we compared the expression of different components of the pituitary TGF-β1 system, including active cytokine content, latent TGF-β-binding protein isoforms, and possible local TGF-β1 activators, in males and females in this model. Furthermore, we evaluated the effects of dopamine and estradiol administration to elucidate their role in TGF-β1 system regulation. The expression of active TGF-β1, latent TGF-β-binding protein isoforms, and several putative TGF-β1 activators evaluated was higher in male than in female mouse pituitary glands. However, Drd2(-/-) female mice were more sensitive to the decrease in active TGF-β1 content, as reflected by the down-regulation of TGF-β1 target genes. Estrogen and dopamine caused differential regulation of several components of the TGF-β1 system. In particular, we found sex- and genotype- dependent regulation of active TGF-β1 content and a similar expression pattern for 2 of the putative TGF-β1 activators, thrombospondin-1 and kallikrein-1, suggesting that these proteins could mediate TGF-β1 activation elicited by dopamine and estradiol. Our results indicate that (1) the loss of dopaminergic tone affects the pituitary TGF-β1 system more strongly in females than in males, (2) males express higher levels of pituitary TGF-β1 system components including active cytokine, and (3) estradiol negatively controls most of the components of the system. Because TGF-β1 inhibits lactotroph proliferation, we propose that the higher levels of the TGF-β1 system in males could protect or delay the development of prolactinomas in Drd2(-/-) male mice.
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Affiliation(s)
- M Victoria Recouvreux
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, Buenos Aires 1428, Argentina.
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14
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Recouvreux MV, Camilletti MA, Rifkin DB, Becu-Villalobos D, Díaz-Torga G. Thrombospondin-1 (TSP-1) analogs ABT-510 and ABT-898 inhibit prolactinoma growth and recover active pituitary transforming growth factor-β1 (TGF-β1). Endocrinology 2012; 153:3861-71. [PMID: 22700773 PMCID: PMC3404347 DOI: 10.1210/en.2012-1007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Prolactinomas are the most prevalent type of secreting pituitary tumors in humans and generally respond well to a medical therapy with dopamine agonists. However, for patients exhibiting resistance to dopaminergic drugs, alternative treatments are desired. Antiangiogenic strategies might represent a potential therapy for these tumors. Thrombospondin 1 (TSP-1) is a large multifunctional glycoprotein involved in multiple biological processes including angiogenesis, apoptosis, and activation of TGF-β1. Because tumors that overexpress TSP-1 grow more slowly, have fewer metastases, and have decreased angiogenesis, TSP-1 provides a novel target for cancer treatment. ABT-510 and ABT-898 are TSP-1 synthetic analogs that mimic its antiangiogenic action. In the present study, we explored the potential effect of ABT-510 and ABT-898 on experimental prolactinomas induced by chronic diethylstilbestrol (DES) treatment in female rats. We demonstrated that a 2-wk treatment with ABT-510 and ABT-898 counteracted the increase in pituitary size and serum prolactin levels as well as the pituitary proliferation rate induced by DES. These inhibitory effects on tumor growth could be mediated by the antiangiogenic properties of the drugs. We also demonstrated that ABT-510 and ABT-898, in addition to their described antiangiogenic effects, increased active TGF-β1 level in the tumors. We postulate that the recovery of the local cytokine activation participates in the inhibition of lactotrope function. These results place these synthetic TSP-1 analogs as potential alternative or complementary treatments in dopamine agonist-resistant prolactinomas.
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Affiliation(s)
- M Victoria Recouvreux
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Cientificas y Técnicas, Vuelta de Obligado 2490, Buenos Aires 1428, Argentina
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15
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Recouvreux MV, Guida MC, Rifkin DB, Becu-Villalobos D, Díaz-Torga G. Active and total transforming growth factor-β1 are differentially regulated by dopamine and estradiol in the pituitary. Endocrinology 2011; 152:2722-30. [PMID: 21521749 PMCID: PMC3115611 DOI: 10.1210/en.2010-1464] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dopamine, acting through the dopamine type 2 receptor (Drd2), is the main inhibitor of pituitary prolactin (PRL) secretion and lactotroph proliferation. TGF-β1 is involved, at least in part, in mediating these actions. It was described that TGF-β1 synthesis in rat pituitary lactotrophs is up-regulated by dopamine and down-regulated by estradiol. TGF-β1 is secreted as a large latent complex. The local regulation of cytokine activation in the pituitary has not yet been explored. In this work, we studied pituitary active and total TGF-β1 content, as well as TGF-β1 mRNA, and the in vivo role of dopamine and estradiol on pituitary TGF-β1 levels. Adult female mice (wild type), and female mice with a null mutation in the Drd2 (Drd2(-/-)), were used. The loss of dopaminergic tone induced a decrease in TGF-β1 mRNA expression, in active and total cytokine content, and in TGF-β type II receptor expression. Dopamine regulation of pituitary TGF-β1 activation process was inferred by the inhibition of active cytokine by in vivo sulpiride treatment. Interestingly, in the absence of dopaminergic tone, estradiol induced a strong increase in active TGF-β1. PRL secretion correlated with active, but not total cytokine. TGF-β1 inhibitory action on lactotroph proliferation and PRL secretion was decreased in Drd2(-/-) pituitary cells, in correlation with decreased TGF-β type II receptor. The study of the TGF-β1 activation process and its regulation is essential to understand the cytokine activity. As an intermediary of dopamine inhibition of lactotroph function, TGF-β1 and local activators may be important targets in the treatment of dopamine agonist-resistant prolactinomas.
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MESH Headings
- Animals
- Cell Proliferation
- Cells, Cultured
- Dopamine Agonists/pharmacology
- Dopamine Agonists/therapeutic use
- Dopamine Antagonists/pharmacology
- Dopamine Antagonists/therapeutic use
- Dopamine D2 Receptor Antagonists
- Estradiol/analogs & derivatives
- Estradiol/pharmacology
- Estradiol/therapeutic use
- Female
- Gene Expression Regulation/drug effects
- Hyperprolactinemia/drug therapy
- Lactotrophs/drug effects
- Lactotrophs/metabolism
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Transgenic
- Pituitary Gland, Anterior/cytology
- Pituitary Gland, Anterior/drug effects
- Pituitary Gland, Anterior/metabolism
- Prolactin/blood
- Prolactin/metabolism
- Protein Serine-Threonine Kinases/metabolism
- RNA, Messenger/metabolism
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Transforming Growth Factor beta/metabolism
- Transforming Growth Factor beta1/genetics
- Transforming Growth Factor beta1/metabolism
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Affiliation(s)
- M Victoria Recouvreux
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, Buenos Aires 1428, Argentina
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16
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García-Tornadú I, Díaz-Torga G, Risso GS, Silveyra P, Cataldi N, Ramirez MC, Low MJ, Libertun C, Becu-Villalobos D. Hypothalamic orexin, OX1, alphaMSH, NPY and MCRs expression in dopaminergic D2R knockout mice. Neuropeptides 2009; 43:267-74. [PMID: 19570576 DOI: 10.1016/j.npep.2009.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 06/05/2009] [Accepted: 06/06/2009] [Indexed: 11/23/2022]
Abstract
In 5-month-old male and female dopamine receptor 2 (D2R) knockout mice food intake per animal was unaltered while food per g BW was increased. We wished to evaluate the effect of D2R disruption on different components of energy balance and food intake regulation. We determined hypothalamic orexin precursor (PPO) expression, its receptor OX1, serum leptin levels, hypothalamic leptin receptor (OBR), circulating and pituitary alpha MSH levels, as well as central MC3 and MC4 receptors and NPY mRNA in wildtype and D2R knockout mice (KO). Loss of D2R caused a marked increase in serum prolactin levels, to higher levels in females compared to male KO mice. On the other hand, it produced a female-specific increase in circulating alphaMSH, and hypothalamic alphaMSH content, while neurointermediate alphaMSH content was decreased in both sexes. No differences were found in hypothalamic NPY, MC3R or MC4R concentration. Hypothalamic PPO mRNA expression was significantly decreased only in female KOs, while OX1 mRNA was not different between genotypes. Serum leptin levels were also similar in both genotypes. Our results show that in female and not in male mice disruption of the D2R produces two potentially anorexigenic events: an increase in serum and hypothalamic alphaMSH, and a decrease in hypothalamic orexin expression. Very high prolactin levels, which are orexigenic, probably counterbalance these effects, so that food intake is slightly altered. In males, on the other hand, hypothalamic PPO, and serum or hypothalamic alphaMSH are not modified, and increased prolactin levels may account for increased food intake per g BW. These results suggest a sexually dimorphic participation of the D2R in food intake regulation.
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Affiliation(s)
- I García-Tornadú
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina
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17
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Cristina C, Díaz-Torga G, Góngora A, Guida MC, Perez-Millán MI, Baldi A, Becu-Villalobos D. Fibroblast growth factor-2 in hyperplastic pituitaries of D2R knockout female mice. Am J Physiol Endocrinol Metab 2007; 293:E1341-51. [PMID: 17848635 DOI: 10.1152/ajpendo.00260.2007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dopamine D2 receptor (D2R) knockout (KO) female mice develop chronic hyperprolactinemia and pituitary hyperplasia. Our objective was to study the expression of the mitogen fibroblast growth factor (FGF2) and its receptor, FGFR1, comparatively in pituitaries from KO and wild-type (WT) female mice. We also evaluated FGF2 subcellular localization and FGF2 effects on pituitary function. FGF2-induced prolactin release showed a similar response pattern in both genotypes, even though basal and FGF2-stimulated release was higher in KO. FGF2 stimulated pituitary cellular proliferation (MTS assay and [(3)H]thymidine incorporation), with no differences between genotypes. FGF2 concentration (measured by ELISA) in whole pituitaries or cultured cells was lower in KO (P < 0.00001 and 0.00014). Immunofluorescence histochemistry showed less FGF2 in pituitaries from KO females and revealed a distinct FGF2 localization pattern between genotypes, being predominantly nuclear in KO and cytosolic in WT pituitaries. Finally, FGF2 could not be detected in the conditioned media from pituitary cultures of both genotypes. FGFR1 levels (Western blot and immunohistochemistry) were higher in pituitaries of KO. Basal concentration of phosphorylated ERKs was lower in KO cells (P = 0.018). However, when stimulated with FGF2, a significantly higher increment of ERK phosphorylation was evidenced in KO cells (P < or = 0.02). We conclude that disruption of the D2R caused an overall decrease in pituitary FGF2 levels, with an increased distribution in the nucleus, and increased FGFR1 levels. These results are important in the search for reliable prognostic indicators for patients with pituitary dopamine-resistant prolactinomas, which will make tumor-specific therapy possible.
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MESH Headings
- Animals
- Blotting, Western
- Cell Growth Processes/physiology
- Enzyme-Linked Immunosorbent Assay
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Female
- Fibroblast Growth Factor 2/metabolism
- Hyperplasia
- Immunohistochemistry
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Confocal
- Microscopy, Fluorescence
- Phosphorylation
- Pituitary Gland, Anterior/cytology
- Pituitary Gland, Anterior/metabolism
- Pituitary Gland, Anterior/pathology
- Prolactin/metabolism
- Prolactinoma/metabolism
- Receptor, Fibroblast Growth Factor, Type 1/metabolism
- Receptors, Dopamine D2/deficiency
- Receptors, Dopamine D2/metabolism
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Affiliation(s)
- Carolina Cristina
- Instituto de Biología y Medicina Experimental, CONICET, V Obligado 2490, 1428, Buenos Aires, Argentina
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18
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Vela J, Pérez-Millán MI, Becu-Villalobos D, Díaz-Torga G. Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells. Am J Physiol Cell Physiol 2007; 293:C951-9. [PMID: 17507432 DOI: 10.1152/ajpcell.00429.2006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The L-type Ca2+ channel is the primary voltage-dependent Ca2+-influx pathway in many excitable and secretory cells, and direct phosphorylation by different kinases is one of the mechanisms involved in the regulation of its activity. The aim of this study was to evaluate the participation of Ser/Thr kinases and tyrosine kinases (TKs) in depolarization-induced Ca2+ influx in the endocrine somatomammotrope cell line GH3. Intracellular Ca2+ concentration ([Ca2+]i) was measured using a spectrofluorometric method with fura 2-AM, and 12.5 mM KCl (K+) was used as a depolarization stimulus. K+ induced an abrupt spike (peak) in [Ca2+]i that was abolished in the presence of nifedipine, showing that K+ enhances [Ca2+]i, preferably activating L-type Ca2+ channels. H89, a selective PKA inhibitor, significantly reduced depolarization-induced Ca2+ mobilization in a concentration-related manner when it was applied before or after K+, and okadaic acid, an inhibitor of Ser/Thr phosphatases, which has been shown to regulate PKA-stimulated L-type Ca2+ channels, increased K+-induced Ca2+ entry. When PKC was activated by PMA, the K+-evoked peak in [Ca2+]i, as well as the plateau phase, was significantly reduced, and chelerythrine (a PKC inhibitor) potentiated the K+-induced increase in [Ca2+]i, indicating an inhibitory role of PKC in voltage-dependent Ca2+ channel (VDCC) activity. Genistein, a TK inhibitor, reduced the K+-evoked increase in [Ca2+]i, but, unexpectedly, the tyrosine phosphatase inhibitor orthovanadate reduced not only basal Ca2+ levels but, also, Ca2+ influx during the plateau phase. Both results suggest that different TKs may act differentially on VDCC activation. Activation of receptor TKs with epidermal growth factor (EGF) or vascular endothelial growth factor potentiated K+-induced Ca2+ influx, and AG-1478 (an EGF receptor inhibitor) decreased it. However, inhibition of the non-receptor TK pp60 c-Src enhanced K+-induced Ca2+ influx. The present study strongly demonstrates that a complex equilibrium among different kinases and phosphatases regulates VDCC activity in the pituitary cell line GH3: PKA and receptor TKs, such as vascular endothelial growth factor receptor and EGF receptor, enhance depolarization-induced Ca2+ influx, whereas PKC and c-Src have an inhibitory effect. These kinases modulate membrane depolarization and may therefore participate in the regulation of a plethora of intracellular processes, such as hormone secretion, gene expression, protein synthesis, and cell proliferation, in pituitary cells.
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Affiliation(s)
- Jorge Vela
- Instituto de Biología y Medicina Experimental, CONICET, V. Obligado 2490, (1428Buenos Aires, Argentina
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19
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Cristina C, García-Tornadú I, Díaz-Torga G, Rubinstein M, Low MJ, Becú-Villalobos D. Dopaminergic D2 receptor knockout mouse: an animal model of prolactinoma. Front Horm Res 2006; 35:50-63. [PMID: 16809922 DOI: 10.1159/000094308] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Dopamine receptor type 2 (D2R) knockout mice (KO) have chronic hyperprolactinemia, pituitary hyperplasia, and a moderate decrease in MSH content. They are also growth retarded evidencing an alteration in the GH-IGF-I axis. In D2R KO, lactotropes do not show dense secretory granules but degranulated cells and fewer somatotropes, gonadotropes and thyrotropes. Prolactin levels are always higher in female than in male knockouts, and in accordance, pituitary hyperplasia is observed at 8 months only in females. After 16 months of age, highly vascularized adenomas develop, especially in females. Prominent vascular channels in the hyperplastic and adenomatous pituitaries, as well as extravasated red blood cells not contained in capillaries is also a common finding. Prolactin is not the factor that enhances the hyperplastic phenotype in females while estrogen is a permissive factor. VEGF-A expression is increased in pituitaries from D2R KO. VEGF-A is expressed in follicle stellate cells. Because D2R receptors are found in lactotropes and not in follicle stellate cells, it may be inferred that a paracrine-derived factor from lactotropes is acting on follicle stellate cells to increase VEGF-A expression. VEGF-A does not induce pituitary cell proliferation, even though it enhances prolactin secretion. But it may act on adjacent endothelial cells and participate in the angiogenic process that increases the availability of different growth factors and mitogens. The D2R knockout mouse represents a unique animal model to study dopamine-resistant prolactinomas, and VEGF-A may be an alternative therapeutic target in this pathology.
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Affiliation(s)
- Carolina Cristina
- Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina
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20
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García-Tornadú I, Rubinstein M, Gaylinn BD, Hill D, Arany E, Low MJ, Díaz-Torga G, Becu-Villalobos D. GH in the dwarf dopaminergic D2 receptor knockout mouse: somatotrope population, GH release, and responsiveness to GH-releasing factors and somatostatin. J Endocrinol 2006; 190:611-9. [PMID: 17003262 DOI: 10.1677/joe.1.06902] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Recently, the importance of the dopaminergic D2 receptor (D2R) subtype in normal body growth and neonatal GH secretion has been highlighted. Disruption of D2R alters the GHRH-GH-IGF-I axis and impairs body growth in adult male mice. The D2R knockout (KO) dwarf mouse has not been well characterized; we therefore sought to determine somatotrope function in the adult pituitary. Using immunohistochemistry and confocal microscopy, we found a significant decrease in the somatotrope population in pituitaries from KO mice (P=0.043), which was paralleled by a decreased GH output from pituitary cells cultured in vitro. In cells from adult mice the response amplitude to GHRH differed between genotypes (lower in KO), but this difference was less dramatic after taking into account the lower basal release and hormone content in the KO cells. Furthermore, there were no significant differences in cAMP generation in response to GHRH between genotypes. By Western blot, GHRH-receptor in pituitary membranes from KO mice was reduced to 46% of the level found in wildtype (WT) mice (P=0.016). Somatostatin induced a concentration-dependent decrease in GH and prolactin (PRL) secretion in both genotypes, and 1x10(-7) M ghrelin released GH in cells from both genotypes (P=0.017) in a proportionate manner to basal levels. These results suggest that KO somatotropes maintain a regulated secretory function. Finally, we tested the direct effect of dopamine on GH and PRL secretion in cells from both genotypes at 20 days and 6 months of life. As expected, we found that dopamine could reduce PRL levels at both ages in WT mice but not in KO mice, but there was no consistent effect of the neurotransmitter on GH release in either genotype at the ages studied. The present study demonstrates that in the adult male D2R KO mouse, there is a reduction in pituitary GH content and secretory activity. Our results point to an involvement of D2R signaling at the hypothalamic level as dopamine did not release GH acting at the pituitary level either in 1-month-old or adult mice. The similarity of the pituitary defect in the D2R KO mouse to that of GHRH-deficient models suggests a probable mechanism. A loss of dopamine signaling via hypothalamic D2Rs at a critical age causes the reduced release of GHRH from hypophyseotropic neurons leading to inadequate clonal expansion of the somatotrope population. Our data also reveal that somatotrope cell number is much more sensitive to changes in neonatal GHRH input than their capacity to develop properly regulated GH-secretory function.
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MESH Headings
- Animals
- Blotting, Western/methods
- Cells, Cultured
- Cyclic AMP/analysis
- Cyclic AMP/biosynthesis
- Dopamine/pharmacology
- Dose-Response Relationship, Drug
- Dwarfism/metabolism
- Ghrelin
- Growth Hormone/metabolism
- Growth Hormone-Releasing Hormone/pharmacology
- Immunohistochemistry/methods
- Male
- Mice
- Mice, Knockout
- Microscopy, Confocal
- Peptide Hormones/pharmacology
- Pituitary Gland/cytology
- Pituitary Gland/drug effects
- Pituitary Gland/metabolism
- Prolactin/metabolism
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Neuropeptide/analysis
- Receptors, Neuropeptide/metabolism
- Receptors, Pituitary Hormone-Regulating Hormone/analysis
- Receptors, Pituitary Hormone-Regulating Hormone/metabolism
- Somatostatin/pharmacology
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Affiliation(s)
- Isabel García-Tornadú
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and University of Buenos Aires, V. Obligado 2490, 1428 Buenos Aires, Argentina
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21
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Cristina C, Díaz-Torga G, Baldi A, Góngora A, Rubinstein M, Low MJ, Becú-Villalobos D. Increased pituitary vascular endothelial growth factor-a in dopaminergic D2 receptor knockout female mice. Endocrinology 2005; 146:2952-62. [PMID: 15817666 DOI: 10.1210/en.2004-1445] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vascular endothelial growth factor (VEGF)-A is an important angiogenic cytokine in cancer and pathological angiogenesis and has been related to the antiangiogenic activity of dopamine in endothelial cells. We investigated VEGF expression, localization, and function in pituitary hyperplasia of dopamine D2 receptor (D2R)-knockout female mice. Pituitaries from knockout mice showed increased protein and mRNA VEGF-A expression when compared with wild-type mice. In wild-type mice, prolonged treatment with the D2R antagonist, haloperidol, enhanced pituitary VEGF expression and prolactin release, suggesting that dopamine inhibits pituitary VEGF expression. VEGF expression was also increased in pituitary cells from knockout mice, even though these cells proliferated less in vitro when compared with wild-type cells, as determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium proliferation assay, proliferating cell nuclear antigen expression, and [(3)H]thymidine incorporation. In contrast to other animal models, estrogen did not increase pituitary VEGF protein and mRNA expression and lowered serum prolactin secretion in vivo and in vitro in both genotypes. VEGF (10 and 30 ng/ml) did not modify pituitary cell proliferation in either genotype and increased prolactin secretion in vitro in estrogen-pretreated cells of both genotypes. But conditioned media from D2R(-/-) cells enhanced human umbilical vein cell proliferation, and this effect could be partially inhibited by an anti-VEGF antiserum. Finally, using dual-labeling immunofluorescence and confocal laser microscopy, we found that in the hyperplastic pituitaries, VEGF-A was mostly present in follicle-stellate cells. In conclusion, pituitary VEGF expression is under dopaminergic control, and even though VEGF does not promote pituitary cellular proliferation in vitro, it may be critical for pituitary angiogenesis through paracrine actions in the D2R knockout female mice.
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Affiliation(s)
- C Cristina
- Consejo Nacional de Investigaciones Científicas y Técnicas, V. Obligado 2490, 1428 Buenos Aires, Argentina
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22
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Suarez C, Díaz-Torga G, González-Iglesias A, Cristina C, Becu-Villalobos D. Upregulation of angiotensin II type 2 receptor expression in estrogen-induced pituitary hyperplasia. Am J Physiol Endocrinol Metab 2004; 286:E786-94. [PMID: 14722030 DOI: 10.1152/ajpendo.00477.2003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent evidence shows that reexpression and upregulation of angiotensin II (ANG II) type 2 (AT2) receptor in adult tissues occur during pathological conditions such as tissue hyperplasia, inflammation, and remodeling. In particular, expression of functional AT2 receptors in the pituitary and their physiological significance and regulation have not been described. In this study, we demonstrate that chronic in vivo estrogen treatment, which induces pituitary hyperplasia, enhances local AT2 expression (measured by Western blot and RT-PCR) concomitantly with downregulation of ANG II type 1 (AT1) receptors. In vivo progesterone treatment of estrogen-induced pituitary hyperplasia did not modify either the ANG II receptor subtype expression pattern or octapeptide-induced and AT1-mediated calcium signaling. Nevertheless, an unexpected potentiation of the ANG II prolactin-releasing effect was observed in this group, and this response was sensitive to both AT1 and AT2 receptor antagonists. These data are the first to document that ANG II can act at the pituitary level through the AT2 receptor subtype and that estrogens display a differential regulation of AT1 and AT2 receptors at this level.
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MESH Headings
- 17-alpha-Hydroxyprogesterone/pharmacology
- Analysis of Variance
- Animals
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Diethylstilbestrol/administration & dosage
- Down-Regulation
- Estrogens, Non-Steroidal/administration & dosage
- Female
- Hyperplasia/chemically induced
- Pituitary Diseases/chemically induced
- Pituitary Diseases/metabolism
- Pituitary Gland/drug effects
- Pituitary Gland/metabolism
- Pituitary Gland/pathology
- Prolactin/drug effects
- Prolactin/metabolism
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/drug effects
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Up-Regulation
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Affiliation(s)
- Cecilia Suarez
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Cieníficas y Técnicas y Técnicas, 1428 Buenos Aires, Argentina
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Suárez C, Díaz-Torga G, Gonzalez-Iglesias A, Vela J, Mladovan A, Baldi A, Becu-Villalobos D. Angiotensin II phosphorylation of extracellular signal-regulated kinases in rat anterior pituitary cells. Am J Physiol Endocrinol Metab 2003; 285:E645-53. [PMID: 12759218 DOI: 10.1152/ajpendo.00015.2003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied the effects of ANG II on extracellular signal-regulated kinase (ERK)1/2 phosphorylation in rat pituitary cells. ANG II increased ERK phosphorylation in a time- and concentration-dependent way. Maximum effect was obtained at 5 min at a concentration of 10-100 nM. The effect of 100 nM ANG II was blocked by the AT1 antagonist DUP-753, by the phospholipase C (PLC) inhibitor U-73122, and by the MAPK kinase (MEK) antagonist PD-98059. The ANG II-induced increase in phosphorylated (p)ERK was insensitive to pertussis toxin blockade and PKC depletion or inhibition. The effect was also abrogated by chelating intracellular calcium with BAPTA-AM or TMB-8 by depleting intracellular calcium stores with a 30-min pretreatment with EGTA and by pretreatment with herbimycin A and PP1, two c-Src tyrosine kinase inhibitors. It was attenuated by AG-1478, an inhibitor of epidermal growth factor receptor (EGFR) activation. Therefore, in the rat pituitary, the increase of pERK is a Gq- and PLC-dependent process, which involves an increase in intracellular calcium and activation of a c-Src tyrosine kinase, transactivation of the EGFR, and the activation of MEK. Finally, the response of ERK activation by ANG II is altered in hyperplastic pituitary cells, in which calcium mobilization evoked by ANG II is also modified.
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Affiliation(s)
- Cecilia Suárez
- Instituto de Biología y Medicina Experimental-CONICET, 1428 Buenos Aires, Argentina
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24
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Suárez C, Tornadú IG, Cristina C, Vela J, Iglesias AG, Libertun C, Díaz-Torga G, Becu-Villalobos D. Angiotensin and calcium signaling in the pituitary and hypothalamus. Cell Mol Neurobiol 2002; 22:315-33. [PMID: 12469873 DOI: 10.1023/a:1020772018703] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
1) In the rat pituitary, angiotensin type 1B receptors (AT1B) are located in lactotrophs and corticotrophs. 2) Activation of AT1B receptors are coupled to Gq/11 (Guanine protein coupled receptor, or GPCR); they increase phospholipase beta C (PLC) activity resulting in inositol 1,4,5 triphosphate (InsP3) and diacylglycerol (DAG) formation. A biphasic increase in [Ca2+]i triggered by InsP3 and DAG ensues. 3) As many GPCRs, AT1B pituitary receptors rapidly desensitize. 4) This was observed in the generation of InsP3, the mobilization of intracellular Ca(2+), and in prolactin release. Both homologous and heterologous desensitization was evidenced. 5) Desensitization of the angiotensin II type 1 (AT1) receptor in the pituitary shares similarities and differences with endogenously expressed or transfected AT1 receptors in different cell types. 6) In the pituitary hyperplasia generated by chronic estrogen treatment there was desensitization or alteration in angiotensin II (Ang II) evoked intracellular Ca2+ increase, InsP3 generation, and prolactin release. This correlates with a downregulation of AT1 receptors. 7) In particular, in hyperplastic cells Ang II failed to evoke a transient acute peak in [Ca2+]i, which was replaced by a persistent plateau phase of [Ca2+]i increase. 8) Different calcium channels participate in Ang II induced [Ca2+]i increase in control and hyperplastic cells. While spike phase in control cells is dependent on intracellular stores sensitive to thapsigargin, in hyperplastic cells plateau increase is dependent on extracellular calcium influx. 9) Signal transduction of the AT1 pituitary receptor is greatly modified by hyperplasia, and it may be an important mechanism in the control of the hyperplastic process. 10) In the hypothalamus and brain stem there is a predominant expression of AT1A and AT2 mRNA. 11) Ang II acts at specific receptors located on neurons in the hypothalamus and brain stem to elicit alterations in blood pressure, fluid intake, and hormone secretion. 12) Calcium channels play important roles in the Ang II induced behavioral and endocrine responses. 13) Ang II, in physiological concentrations, can activate AT1 receptors to stimulate both Ca2+ release from intracellular stores and Ca2+ influx from the extracellular space to increase [Ca2+]i in polygonal and stellate astroglia of the hypothalamus and brain stem. 14) In primary cell culture of neurons from newborn rat hypothalamus and brain stem, it has also been determined that Ang II elicits an AT1 receptor mediated inhibition of delayed rectifier K(+) current and a stimulation of Ca2+ current. 15) In primary cell cultures derived from the subfornical organ or the organum vasculosum laminae terminalis of newborn rat pups, Ang II produced a pronounced desensitization of the [Ca2+]i response. 16) Hypothalamic and pituitary Ang II systems are involved in different functions, some of which are related. At both levels Ang II signals through [Ca2+]i in a characteristic way.
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Affiliation(s)
- Cecilia Suárez
- Instituto de Biología y Medicina Experimental, CONICET, V. Obligado 2490, Buenos Aires, Argentina
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25
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Díaz-Torga G, Feierstein C, Libertun C, Gelman D, Kelly MA, Low MJ, Rubinstein M, Becú-Villalobos D. Disruption of the D2 dopamine receptor alters GH and IGF-I secretion and causes dwarfism in male mice. Endocrinology 2002; 143:1270-9. [PMID: 11897683 DOI: 10.1210/endo.143.4.8750] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We determined the consequences of the loss of D2 receptors (D2R) on the GH-IGF-I axis using mice deficient in functional dopamine D2 receptors by targeted mutagenesis (D2R(-/-)). Body weights were similar at birth, but somatic growth was less in male D2R(-/-) mice from 1-8 months of age and in D2R(-/-) females during the first 2 months. The rate of skeletal maturation, as indexed by femur length, and the weight of the liver and white adipose tissue were decreased in knockout male mice even though food intake was not altered. The serum GH concentration was significantly decreased during the first 2 months in knockout female and male mice, and IGF-I and IGF-binding protein-3 levels were lower in knockout mice. PRL was significantly higher in knockout mice, and females attained higher levels than males. Pituitaries from adult knockout mice had impaired basal GH release and a lower response to GHRH in vitro. We propose that the D2R participates in GHRH/GH release in the first month of life. In accordance, the D2R antagonist sulpiride lowered GH levels in 1-month-old wild-type mice. Our results indicate that lack of D2R alters the GHRH-GH-IGF-I axis, and impairs body growth and the somatotrope population.
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Affiliation(s)
- G Díaz-Torga
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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26
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González Iglesias A, Suárez C, Feierstein C, Díaz-Torga G, Becu-Villalobos D. Desensitization of angiotensin II: effect on [Ca2+]i, inositol triphosphate, and prolactin in pituitary cells. Am J Physiol Endocrinol Metab 2001; 280:E462-70. [PMID: 11171601 DOI: 10.1152/ajpendo.2001.280.3.e462] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of pituitary angiotensin (ANG II) type 1 receptors (AT1) mobilizes intracellular Ca2+, resulting in increased prolactin secretion. We first assessed desensitization of AT1 receptors by testing ANG II-induced intracellular Ca2+ concentration ([Ca2+](i)) response in rat anterior pituitary cells. A period as short as 1 min with 10(-7) M ANG II was effective in producing desensitization (remaining response was 66.8 +/- 2.1% of nondesensitized cells). Desensitization was a concentration-related event (EC(50): 1.1 nM). Although partial recovery was obtained 15 min after removal of ANG II, full response could not be achieved even after 4 h (77.6 +/- 2.4%). Experiments with 5 x 10(-7) M ionomycin indicated that intracellular Ca2+ stores of desensitized cells had already recovered when desensitization was still significant. The thyrotropin-releasing hormone (TRH)-induced intracellular Ca2+ peak was attenuated in the ANG II-pretreated group. ANG II pretreatment also desensitized ANG II- and TRH-induced inositol phosphate generation (72.8 +/- 3.5 and 69.6 +/- 6.1%, respectively, for inositol triphosphate) and prolactin secretion (53.4 +/- 2.3 and 65.1 +/- 7.2%), effects independent of PKC activation. We conclude that, in pituitary cells, inositol triphosphate formation, [Ca2+](i) mobilization, and prolactin release in response to ANG II undergo rapid, long-lasting, homologous and heterologous desensitization.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Calcium/metabolism
- Cells, Cultured
- Drug Tolerance
- Female
- Inositol 1,4,5-Trisphosphate/metabolism
- Ionomycin/pharmacology
- Pituitary Gland, Anterior/drug effects
- Pituitary Gland, Anterior/metabolism
- Prolactin/metabolism
- Protein Kinase C/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/drug effects
- Receptors, Angiotensin/physiology
- Tetradecanoylphorbol Acetate/pharmacology
- Thyrotropin-Releasing Hormone/pharmacology
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Affiliation(s)
- A González Iglesias
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Cientificas y Técnicas, 1428 Buenos Aires, Argentina
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27
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González Iglesias A, Díaz-Torga G, Piroli G, Achával-Zaia R, De Nicola AF, Libertun C, Becu-Villalobos D. Bromocriptine restores angiotensin II response in pituitary hyperplasia. Mol Cell Endocrinol 2000; 165:67-74. [PMID: 10940485 DOI: 10.1016/s0303-7207(00)00270-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In estrogen-induced pituitary hyperplasia AII-evoked prolactin release is decreased and the octapeptide does not generate a spike elevation in [Ca(2+)](i) in vitro. We studied whether or not bromocriptine could restore AII response in diethylstilbestrol treated rats. Co-administration of bromocriptine resulted in involution of pituitary size and lowering of serum prolactin. In vitro, prolactin release per cell was reduced in the hyperplastic group, and levels were not significantly increased by in vivo bromocriptine treatment. Immunocytochemical analysis revealed that hyperplastic pituitaries contained fewer prolactin granules than control pituitaries, and that bromocriptine, did not increase prolactin storage. Nevertheless, in this group, prolactin response to AII increased, and AII evoked a consistent spike in [Ca(2+)](i), albeit lower than in the control group. Such spike was abolished by thapsigargin, and not by removal of extracellular calcium or by K(+), indicating that it was mainly dependent on intracellular calcium stores, as in normal cells. We conclude that bromocriptine treatment partially restores AII response in the hyperplastic pituitary.
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Affiliation(s)
- A González Iglesias
- Instituto de Biología y Medicina Experimental, CONICET, Vuelta de Obligado 2490, (1428), Buenos Aires, Argentina
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28
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Lacau-Mengido IM, González Iglesias A, Díaz-Torga G, Thyssen-Cano S, Libertun C, Becú-Villalobos D. Effect of stage of development and sex on gonadotropin-releasing hormone secretion in in vitro hypothalamic perifusion. Proc Soc Exp Biol Med 1998; 217:445-9. [PMID: 9521091 DOI: 10.3181/00379727-217-44255] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Marked sexual and ontogenic differences have been described in gonadotropin regulation in the rat. These could arise from events occurring both at the hypothalamic or hypophyseal levels. The present experiments were designed to evaluate the capacity of the hypothalamus in releasing GnRH in vitro, basally and in response to depolarization with KCl, during ontogeny in the rat. To that end we chose two well-defined developmental ages that differ markedly in sexual and ontogenic characteristics of gonadotropin regulation, 15 and 30 days. We compared GnRH release from hypothalami of females, neonatal androgenized females and males. Mediobasal hypothalami were perifused in vitro, and GnRH measured in the effluent. Basal secretion of the decapeptide increased with age in the three groups with no sexual differences encountered. When studying GnRH release induced by membrane depolarization, no differences within sex or age were encountered. On the other hand FSH serum levels decreased with age in females and increased in males, and in neonatal androgenized females followed a similar pattern to that of females. LH levels were higher in infantile females than in age-matched males or androgenized females. Such patterns of gonadotropin release were therefore not correlated to either basal or K+-induced GnRH release from the hypothalamus. We conclude that sexual and ontogenic differences in gonadotropin secretion in the developing rat are not dependent on the intrinsic capability of the hypothalamus to release GnRH in response to membrane depolarization. The hormonal differences observed during development and between sexes are probably related to differences in the sensitivity of the GnRH neuron to specific secretagogue and neurotransmitter regulation, and/or to differences in hypophyseal GnRH receptors and gonadotrope sensitivity.
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Affiliation(s)
- I M Lacau-Mengido
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
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29
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Díaz-Torga G, González Iglesias A, Achával-Zaia R, Libertun C, Becú-Villalobos D. Angiotensin II-induced Ca2+ mobilization and prolactin release in normal and hyperplastic pituitary cells. Am J Physiol 1998; 274:E534-40. [PMID: 9530138 DOI: 10.1152/ajpendo.1998.274.3.e534] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We evaluated the effects of angiotensin II (ANG II) and its antagonists on prolactin release, intracellular calcium ([Ca2+]i) mobilization, and [3H]thymidine uptake in cells from normal rat pituitaries and from estrogen-induced pituitary tumors. ANG II (10(-7) to 10(-9) M) increased prolactin release significantly in control and not in tumoral cells. In control cells, ANG II (10(-6) to 10(-9) M) produced an immediate spike of [Ca2+]i followed by a plateau. Spike levels rose significantly between 10(-10) and 10(-8) M ANG II, whereas the onset of the spike was retarded with decreasing concentrations. In tumoral cells, ANG II did not produce a spike phase even at 10(-6) M. ANG II-induced prolactin release and calcium mobilization were blocked by losartan (AT1 receptor antagonist) and not by PD-123319 (AT2 antagonist). Finally, [3H]thymidine uptake was not modified by ANG II (10(-7) to 10(-10) M) or its antagonists in either group. Our results suggest that chronic in vivo estrogenic treatment alters in vitro pituitary response to ANG II. Alterations might function to limit excessive prolactin secretion of hypersecreting tumors. Besides, ANG II does not modify DNA synthesis in vitro of cells from normal or tumor-derived hypophyses.
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Affiliation(s)
- G Díaz-Torga
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas V, Buenos Aires, Argentina
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30
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Becú-Villalobos D, González Iglesias A, Díaz-Torga G, Hockl P, Libertun C. Brain sexual differentiation and gonadotropins secretion in the rat. Cell Mol Neurobiol 1997; 17:699-715. [PMID: 9442354 DOI: 10.1023/a:1022542221535] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. The present work deals with sexual differences in gonadotropin regulation in the rat and the role of sexual organization of the hypothalamus in determining such differences. 2. Sex differences between male and female rats, with regard to their control of gonadotropin secretion, go beyond whether or not gonadotropins are released cyclically. Rats show additional sex differences (a) in the response of gonadotropins to removal and imposition of negative feedback signals and (b) in the ontogeny of gonadotropin regulation from birth to puberty. 3. There is a sensitive developmental period during which sexual differentiation of neural substrates proceeds irreversibly under the influence of gonadal hormones. In the rat this period starts a few days before birth and ends approximately 10 days after birth. Female rats treated during this sensitive period with androgens or estrogens will permanently lose the capacity to release GnRH in response to estrogenic stimulation. 4. Nevertheless although sexual differentiation is dramatically affected by events during the neonatal period, recent data question the "critical" nature of this period, as it has been shown that testosterone can still act on neural substrates well beyond (15 to 30 days of age) the neonatal period to defeminize and masculinize endocrine and behavioral functions. 5. Furthermore, the capacity for the normal display of female sexual behavior and for the cyclic release of gonadotropins is not, as has been assumed, inherent to central nervous tissue but depends on active hormonal estrogenic induction during a sensitive period of development. 6. Besides, during differentiation of male sexual brain function estrogens may be supportive, rather than directive, to the primary action of androgens. 7. Serotonergic, noradrenergic, and opioid systems participate in the sexual dimorphism in gonadotropin control in adult rats. 8. The sex difference in the postcastration LH rise is dependent on the early sexual organization of the hypothalamus, even though in adulthood it can also be influenced by a variety of factors such as the stage of the estrous cycle, age of the animal, estradiol pretreatment, and history of release from feedback inhibition. 9. The characteristic pattern of gonadotropin secretion in the female infantile rat, which is sexually differentiated, can be related to an increase in hypophyseal receptors coupled to an increase in the intracellular calcium response to GnRH. Such events depend on the sexual organization of the hypothalamus. In males the greater sensitivity to GnRH at 30 days is reflected in an increase in pituitary GnRH receptors but not in an increase in the magnitude of Ca2+ mobilization induced by GnRH, therefore it is probable that in this situation alternative second messengers may modulate high sensitivity. Neonatal androgenization of the hypothalamus may decrease the hypophyseal response to GnRH by an alteration in receptor concentration and signal transduction during the infantile period. 10. Finally, serotonergic, dopaminergic, opioid, and noradrenergic regulation of GnRH varies with increasing age, and the sexual organization of the hypothalamus by testosterone or estrogens is a determinant in such regulation.
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Affiliation(s)
- D Becú-Villalobos
- Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina
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Piroli G, Lima AE, Díaz-Torga G, De Nicola AF. Biochemical parameters in the anterior pituitary during the course of tumorigenesis induced by diethylstilbestrol treatment. J Steroid Biochem Mol Biol 1994; 51:183-9. [PMID: 7981127 DOI: 10.1016/0960-0760(94)90092-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Treatment of F344 rats with diethylstilbestrol (DES) for 1-2 months induces a prolactin (PRL)-secreting pituitary adenoma. After 8 weeks of DES treatment, we have shown that the ratio of regulatory subunits of the cAMP-dependent protein kinase (RI/RII) increased in the tumors. Presently we report the variations in RI/RII ratio, pituitary weight, DNA content, serum PRL, nuclear estrogen receptor (E2R) and of ornithine decarboxylase (ODC) activity from the time of DES pellet implantation until 8 weeks. Pituitary weight, DNA content and serum PRL rose significantly at 4 weeks with a maximum at 6-8 weeks, and significantly correlated with each other. E2R and ODC activity increased from week 1 onwards, with a maximum at 2 weeks and decreased at 8 weeks. Both variables showed a positive correlation but neither E2R nor ODC activity correlated with pituitary weight, DNA or serum PRL. Values for RI remained stable with time, but RII decreased progressively. The RI/RII ratio was maintained around unity between 1-4 weeks, increasing to 1.6-2 thereafter. This ratio positively correlated with pituitary weight and DNA. It is suggested that during tumor induction by estrogen in a sensitive strain of rats, growth signals with different time-courses become activated. Increases in pituitary weight and DNA content, indicators of mammotroph hypertrophy and hyperplasia, were preceded by early rises in E2R and ODC activity. Increases in the RI/RII ratio accompanied the adenomatous change, suggesting their role in cell transformation after 6 weeks of estrogen exposure.
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Affiliation(s)
- G Piroli
- Laboratorio de Bioquimica Neuroendócrina, Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina
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Díaz-Torga G, Becú-Villalobos D, Lacau de Mengido IM, Libertun C. Sexual and ontogenic differences in K(+)-induced gonadotropin and prolactin release in vitro. Brain Res Dev Brain Res 1992; 70:103-8. [PMID: 1473270 DOI: 10.1016/0165-3806(92)90108-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ontogenic and sexual differences have been described in the regulation of anterior pituitary hormone release. In the present experiments we studied basal release and the effect of a depolarizing concentration of K+ on in vitro gonadotropin and prolactin release from anterior pituitaries of male and female rats at 12, 20 and 28 days of age. Basal release of LH and FSH increased with age, values obtained from female glands being significantly higher than those obtained from male glands. K(+)-induced release of LH did not present differences among ages, although the response in females was always greater than that in age-matched males. If K(+)-induced release of LH was considered in relation to basal release, infantile 12-day-old rats of both sexes, had a significantly greater sensitivity to the effect of K+ in comparison to older ages, as has been described for the LH-releasing effect of LHRH and of other stimuli. K(+)-induced FSH release was maximal in females at 20 days of age, and in males at 28 days of age. Percentage increase relative to basal values, induced by K+ was also greatest at 12 days in both sexes, although values from female glands were significantly higher than those from males. Basal and K(+)-induced prolactin release increased significantly with age in both sexes. Basal prolactin release was greater in females than in males at 28 days of age, and no other sexual difference was evidenced.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G Díaz-Torga
- Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina
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