Universidad de Buenos Aires Facultad de Ciencias Veterinarias ...
The seasonal control of reproduction through the photoperiodic information relies on melatonin as the key messenger acting on the components of the hypothalamic-pituitary-gonadal axis (H.H.G.). This hormone is produced in the pineal gland by the enzyme AANAT, and binds to the MT1 and MT2 receptors o...
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| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español |
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Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2018
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| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_2199 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_2199.dir/2199.PDF |
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I28-R145-HWA_2199 |
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dspace |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-145 |
| collection |
Repositorio Digital de la Universidad de Buenos Aires (UBA) |
| language |
Español |
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spa |
| topic |
VIZCACHA FOTOPERIODO MELATONINA REPRODUCCION VIZCACHA FOTOPERIODO REPRODUCCION AMERICA DEL SUR Reproducción |
| spellingShingle |
VIZCACHA FOTOPERIODO MELATONINA REPRODUCCION VIZCACHA FOTOPERIODO REPRODUCCION AMERICA DEL SUR Reproducción Charif, Santiago Elias Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... |
| topic_facet |
VIZCACHA FOTOPERIODO MELATONINA REPRODUCCION VIZCACHA FOTOPERIODO REPRODUCCION AMERICA DEL SUR Reproducción |
| description |
The seasonal control of reproduction through the photoperiodic information relies on melatonin as the key messenger acting on the components of the hypothalamic-pituitary-gonadal axis (H.H.G.). This hormone is produced in the pineal gland by the enzyme AANAT, and binds to the MT1 and MT2 receptors of the hypothalamus, pituitary and ovary, where it modulates the secretion of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and the sex steroids estradiol and progesterone, respectively. The South American plains vizcacha (Lagostomus maximus) shows unique reproductive features, such as natural poliovulation of\nup to 800 oocytes per estral cycle, inhibition of follicular atresia, a prolonged pregnancy with selective embryo reabsorption and follicular recruitment, and pseudo-ovulation with generation of accesory corpora lutea accessories during pregnancy. It displays two reproductive periods\nper year, being the one from April to August more efficient than the one from October to\nFebruary. The aim of this work was to study the influence of the photoperiod on the vizcacha?s H.H.G. axis functioning. First, the mRNA sequence of hypothalamic prepro-GnRH was determined. Two isoforms that differ in the length of the 5?-UTR sequence were found. The\nGnRH variant determined was mGnRH, and showed a high degree of conservation among related caviomorphs, while the sequence of the GnRH-associated peptide (GAP) showed high variability. The analysis melatoninergic system expression throughout the reproductive cycle of the vizcacha resulted in the co-localization of GnRH with both melatonin receptors\nin hypothalamic nuclei that modulate reproduction, the preoptic area and the supraoptic and suprachiasmatic nuclei. In addition, an increase in AANAT expression and melatonin levels was determined as pregnancy progressed, and the lowest levels of hypothalamic MT1 and MT2 were registered at mid-pregnancy. This would indicate that the melatoninergic system\ncontributes to the maintenance of the extensive gestation of the vizcacha. The effect of light\navailability was determined in vizcachas at the follicular phase and at the induced luteal phase. In the first case, continuous exposure to light reduced serum levels of melatonin but increased the expression of AANAT and increased the number of antral follicles and corpora\nlutea, progesterone levels and MT2 expression in the ovary, while constant darkness increased\nGnRH and MT1 levels, serum estradiol levels and MT1 expression in the ovary. In animals at luteal phase, light increased melatonin and LH levels, while darkness stimulated the expression of AANAT and hypothalamic MT1. These results would indicate that the photoperiodic and\nhormonal imbalances differentially alter the response of the hypothalamus, pituitary and\novary depending on the stage of the estrous cycle. Hypothalamic expression of the estrogen receptors ? (RE?) and ? (RE?) also varied with light availability; at the follicular phase, an\nincrease in RE? levels was observed with light and an increase in RE? with darkness. On the other hand, in animals at luteal phase, constant light increased the hypothalamic expression of RE?. In pulsatility assays, it was observed that melatonin stimulates GnRH and LH secretion in females with induced ovulation. Also, the inhibitory effect of neurostradiol on GnRH\nsecretion was determined, while the incubation with melatonin reversed this effect. On the other hand, the joint incubation of melatonin with estradiol or with an RE? agonist increased GnRH release, suggesting that the interaction of melatonin and estradiol is necessary for the\nactivity of the H.H.G. axis In conclusion, this is the first work that shows that in the vizcacha the regulation of each organ through photoperiodic information, as well as its response to\nmelatonin and the hormonal context of the estrous cycle, converge in the modulation of the reproductive axis in a way to adjust the beginning of the activity of the H.H.G. axis with the most favorable season for reproduction. This particular regulation, dependent on the stage of\nthe estrous cycle and on the light availability, demonstrates the relevance of environmental\ninformation for carrying out a successful gestation and highlights the importance of this species as a valuable model of neuroendocrine regulation of reproduction in mammals. |
| author2 |
Vitullo, Alfredo Daniel |
| author_facet |
Vitullo, Alfredo Daniel Charif, Santiago Elias |
| format |
Tesis doctoral Tesis doctoral acceptedVersion |
| author |
Charif, Santiago Elias |
| author_sort |
Charif, Santiago Elias |
| title |
Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... |
| title_short |
Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... |
| title_full |
Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... |
| title_fullStr |
Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... |
| title_full_unstemmed |
Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... |
| title_sort |
universidad de buenos aires facultad de ciencias veterinarias ... |
| publisher |
Universidad de Buenos Aires. Facultad de Ciencias Veterinarias |
| publishDate |
2018 |
| url |
http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_2199 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_2199.dir/2199.PDF |
| work_keys_str_mv |
AT charifsantiagoelias universidaddebuenosairesfacultaddecienciasveterinarias AT charifsantiagoelias acciondelfotoperiodosobrelamodulaciondelejereproductivoenlavizcachadelasllanurasdesudamericalagostomusmaximus |
| _version_ |
1824356441558876160 |
| spelling |
I28-R145-HWA_21992024-08-27 Universidad de Buenos Aires Facultad de Ciencias Veterinarias ... The seasonal control of reproduction through the photoperiodic information relies on melatonin as the key messenger acting on the components of the hypothalamic-pituitary-gonadal axis (H.H.G.). This hormone is produced in the pineal gland by the enzyme AANAT, and binds to the MT1 and MT2 receptors of the hypothalamus, pituitary and ovary, where it modulates the secretion of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and the sex steroids estradiol and progesterone, respectively. The South American plains vizcacha (Lagostomus maximus) shows unique reproductive features, such as natural poliovulation of\nup to 800 oocytes per estral cycle, inhibition of follicular atresia, a prolonged pregnancy with selective embryo reabsorption and follicular recruitment, and pseudo-ovulation with generation of accesory corpora lutea accessories during pregnancy. It displays two reproductive periods\nper year, being the one from April to August more efficient than the one from October to\nFebruary. The aim of this work was to study the influence of the photoperiod on the vizcacha?s H.H.G. axis functioning. First, the mRNA sequence of hypothalamic prepro-GnRH was determined. Two isoforms that differ in the length of the 5?-UTR sequence were found. The\nGnRH variant determined was mGnRH, and showed a high degree of conservation among related caviomorphs, while the sequence of the GnRH-associated peptide (GAP) showed high variability. The analysis melatoninergic system expression throughout the reproductive cycle of the vizcacha resulted in the co-localization of GnRH with both melatonin receptors\nin hypothalamic nuclei that modulate reproduction, the preoptic area and the supraoptic and suprachiasmatic nuclei. In addition, an increase in AANAT expression and melatonin levels was determined as pregnancy progressed, and the lowest levels of hypothalamic MT1 and MT2 were registered at mid-pregnancy. This would indicate that the melatoninergic system\ncontributes to the maintenance of the extensive gestation of the vizcacha. The effect of light\navailability was determined in vizcachas at the follicular phase and at the induced luteal phase. In the first case, continuous exposure to light reduced serum levels of melatonin but increased the expression of AANAT and increased the number of antral follicles and corpora\nlutea, progesterone levels and MT2 expression in the ovary, while constant darkness increased\nGnRH and MT1 levels, serum estradiol levels and MT1 expression in the ovary. In animals at luteal phase, light increased melatonin and LH levels, while darkness stimulated the expression of AANAT and hypothalamic MT1. These results would indicate that the photoperiodic and\nhormonal imbalances differentially alter the response of the hypothalamus, pituitary and\novary depending on the stage of the estrous cycle. Hypothalamic expression of the estrogen receptors ? (RE?) and ? (RE?) also varied with light availability; at the follicular phase, an\nincrease in RE? levels was observed with light and an increase in RE? with darkness. On the other hand, in animals at luteal phase, constant light increased the hypothalamic expression of RE?. In pulsatility assays, it was observed that melatonin stimulates GnRH and LH secretion in females with induced ovulation. Also, the inhibitory effect of neurostradiol on GnRH\nsecretion was determined, while the incubation with melatonin reversed this effect. On the other hand, the joint incubation of melatonin with estradiol or with an RE? agonist increased GnRH release, suggesting that the interaction of melatonin and estradiol is necessary for the\nactivity of the H.H.G. axis In conclusion, this is the first work that shows that in the vizcacha the regulation of each organ through photoperiodic information, as well as its response to\nmelatonin and the hormonal context of the estrous cycle, converge in the modulation of the reproductive axis in a way to adjust the beginning of the activity of the H.H.G. axis with the most favorable season for reproduction. This particular regulation, dependent on the stage of\nthe estrous cycle and on the light availability, demonstrates the relevance of environmental\ninformation for carrying out a successful gestation and highlights the importance of this species as a valuable model of neuroendocrine regulation of reproduction in mammals. Fil: Charif, Santiago Elias. Universidad de Buenos Aires. Facultad de Ciencias Veterianas. Buenos Aires, Argentina Vitullo, Alfredo Daniel Dorfman, Verónica Berta Charif, Santiago Elias 2018-03-09 El control estacional de la reproducción a través de la información fotoperiódica se basa en la melatonina como mensajero clave que actúa sobre los componentes del eje hipotalámicohipofisario-\ngonadal (H.H.G.). Esta hormona es producida en la glándula pineal por la enzima AANAT, y se une a los receptores MT1 y MT2 del hipotálamo, hipófisis y ovario, modulando la secreción de la hormona liberadora de gonadotropinas (GnRH), la hormona luteinizante\n(LH) y los esteroides sexuales estradiol y progesterona, respectivamente. La vizcacha de las llanuras de Sudamérica (Lagostomus maximus) posee caracteres reproductivos únicos, como poliovulación natural de hasta 800 oocitos por ciclo estral, inhibición de la atresia folicular, una preñez prolongada con reabsorción embrionaria selectiva y reclutamiento folicular, y una pseudo-ovulación con generación de cuerpos lúteos accesorios durante la\ngestación. Presenta dos períodos reproductivos al año, siendo el que va de abril a agosto más eficiente que el que abarca de octubre a febrero. El objetivo de este trabajo fue estudiar\nla in?uencia del fotoperíodo sobre el funcionamiento del eje H.H.G. de la vizcacha. En primer lugar se determinó la secuencia del ARNm de la prepro-GnRH hipotalámica. Se encontraron dos isoformas que difieren únicamente en el largo de la secuencia 5?-UTR. La variante de GnRH determinada fue mGnRH, y presentó un alto grado de conservación entre caviomorfos emparentados, mientras que la secuencia del péptido asociado a GnRH (GAP) mostró alta\nuna variabilidad. El análisis de la expresión del sistema melatoninérgico a lo largo del ciclo reproductivo de la vizcacha arrojó como resultado la co-localización de GnRH con ambos\nreceptores de melatonina en núcleos hipotalámicos que controlan la reproducción, el área preóptica y los núcleos supraóptico y supraquiasmático. Además, se determinó un incremento\nde la expresión de AANAT y de los niveles de melatonina conforme progresa la gestación, y los menores niveles de MT1 y MT2 hipotalámicos se registraron en la etapa media de la preñez.\nEsto indicaría que el sistema melatoninérgico contribuye al mantenimiento de la extensa gestación de la vizcacha. El efecto de la disponibilidad lumínica se determinó en vizcachas\nen fase folicular y en fase lútea inducida. En el primer caso, la exposición contínua a la luz redujo los niveles séricos de melatonina pero incrementó la expresión de AANAT y en el ovario\naumentó el número de folículos antrales y de cuerpos lúteos, los niveles de progesterona y la expresión de MT2, mientras que la oscuridad constante incrementó los niveles de GnRH y MT1, los niveles séricos de estradiol y la expresión de MT1 en el ovario. En animales en fase\nlútea, la luz incrementó los niveles de melatonina y de LH, mientras que la oscuridad estimuló\nla expresión de AANAT y del MT1 hipotalámico. Estos resultados indicarían que los desajustes fotoperiódicos y hormonales alteran la respuesta del hipotálamo, de la hipófisis y del ovario\nde manera diferencial en función de la etapa del ciclo estral. La expresión hipotalámica de los receptores de estrógenos ? (RE?) y ? (RE?) también varió con la disponibilidad lumínica; en animales en fase folicular se observó un incremento de los niveles de RE? con la luz y un aumento de RE? con la oscuridad. Por otro lado, en animales en fase lútea, la luz constante aumentó la expresión hipotalámica del RE?. En ensayos de pulsatilidad, se observó que\nla melatonina estimula la secreción de GnRH y de LH en hembras con ovulación inducida. Asimismo, se determinó el efecto inhibitorio del neuroestradiol sobre la secreción de GnRH, mientras que la incubación con melatonina revirtió ese efecto. Por otro lado, la incubación\nconjunta de melatonina con estradiol o con un agonista del RE? incrementó la liberación de GnRH, sugiriendo que la interacción de melatonina y estradiol resulta necesaria para la\nactividad del eje H.H.G. En conclusión, este es el primer trabajo que demuestra que en la vizcacha, la regulación de cada órgano a través de la información fotoperódica, así como su respuesta a la melatonina y el contexto hormonal del ciclo estral, confluyen en la modulación\ndel eje reproductivo de manera de ajustar el inicio de la actividad del eje H.H.G. con la estación más favorable para la reproducción. Esta regulación particular, dependiente de la etapa del ciclo estral y de la disponibilidad lumínica, demuestra la relevancia de la información ambiental para llevar a cabo una gestación exitosa y remarca la importancia de esta especie como un valioso modelo de regulación neuroendócrina de la reproducción en mamíferos. application/pdf VIZCACHA FOTOPERIODO MELATONINA REPRODUCCION spa Universidad de Buenos Aires. Facultad de Ciencias Veterinarias info:eu-repo/semantics/openAccess creative commons/licences/by-nc/2.5/ar VIZCACHA FOTOPERIODO REPRODUCCION AMERICA DEL SUR Reproducción Doctor de la Universidad de Buenos Aires en Ciencias Veterinarias Acción del fotoperíodo sobre la modulación del eje reproductivo en la vizcacha de las llanuras de sudamérica (Lagostomus maximus) info:eu-repo/semantics/doctoralThesis info:ar-repo/semantics/tesis doctoral info:eu-repo/semantics/acceptedVersion http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_2199 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_2199.dir/2199.PDF |