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Doctoral Thesis
DOI
10.11606/T.42.2017.tde-16112017-175827
Document
Author
Full name
Marina Augusto Silveira
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Frazão, Renata (President)
Abdulkader, Fernando Rodrigues de Moraes
Canteras, Newton Sabino
Grande, Beatriz de Carvalho Borges Del
Moenter, Suzanne
Title in Portuguese
Controle neuroendócrino da reprodução: fatores que modulam a atividade de neurônios GNRH e kisspetina.
Keywords in Portuguese
Estradiol
GnRH
Kisspeptina
Patch-clamp
Prolactina
Abstract in Portuguese
Neurônios GnRH e kisspeptina representam as populações neuronais de maior importância no controle da reprodução. Estradiol liga-se ao seu receptor expresso pelos neurônios kisspeptina para regular a libertação de GnRH. No modelo animal OVX+E a atividade do neurônio GnRH e pico de LH é depende do estradiol e hora do dia. Nesse estudo, embora a taxa de disparo dos neurônios GnRH seja similar entre os grupos, o padrão dos potenciais revelou uma mudança para maior duração do estouro em camundongos no proestrous, além do fato de uma maior resposta da hipófise. A prolactina tem grande impacto na modulação do eixo HPG e kisspeptina são mediadores dos efeitos da prolactina sobre a reprodução. Uma pequena porcentagem de neurônios de kisspeptina do AVPV foi indiretamente despolarizada pela prolactina. Este efeito requeria a via de sinalização PI3K. Camundongos portadores de inativação de Stat5a/b em células kisspeptina exibiram um início precoce de ciclicidade estro, indicando que os fatores de transcrição STAT5 exercem um efeito inibitório sobre o momento da puberdade.
Title in English
Neural control of reproduction: neuromodulators of GnRH and kisspeptin neurons activity.
Keywords in English
Estradiol
GnRH
Kisspeptin
Patch-clamp
Prolactin
Abstract in English
GnRH and kisspeptina neurons represent the most important neuronal populations in the control of reproduction. Estradiol binds to its receptor expressed by the kisspeptina neurons to regulate the release of GnRH. In the animal model OVX+E the activity of the GnRH neuron and LH surge is dependent of estradiol and time of day. In this study, although the firing rate of GnRH neurons was similar between groups, the pattern of potentials revealed a change to longer burst duration in mice in proestrous, and the pituitary response was greater in this group. Prolactin has impact on HPG axis modulation and kisspeptin is a mediator of the effects of prolactin on reproduction. A small percentage of AVPV kisspeptin neurons were indirectly depolarized by prolactin. This effect required the PI3K signaling pathway. Mice bearing Stat5a/b inactivation on kisspeptin cells exhibited an early onset of estrus cyclicity, indicating that STAT5 transcription factors exert an inhibitory effect on the time of puberty.
 
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Publishing Date
2017-11-16
 
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