Axônios contendo neuropeptídeo Y em proximidade à neurônios contendo kisspeptina no hipotálamo de ovelhas

• Autor(a) principal: Macedo, Gustavo Guerino
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1443
• topic: Eficiência produtiva; Eixo hipotalâmico gonadotrópico; Productive efficiency; Gonadotropic hypothalamic axis; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

The reproductive axis responds to changing on levels of metabolic factors. However, cellular and molecular mechanisms linking energy balance and reproduction, as well the brain sites for this function remain not well understood. Neuroendocrine peptides like neuropeptide Y (NPY) and kisspeptin are considered to have a major function signaling nutrition to reproduction. NPY is a peptide with a potent orexigenic effect and kisspeptin is the most important stimulator of the releasing of the gonadotrophin-releasing hormone (GnRH)/luteinizing hormone (LH). To evaluate the role of NPY on the modulation of the kisspeptin releasing is necessary to establish the anatomic bases between this two neuropeptides in the hypothalamus. The experimental model used was ovariectomized crossbreed Suffolk ewes with subcutaneous estradiol implant. Animals were euthanatized and hypothalamic tissue assayed to double-label immunofluorescence to detect NPY and kisspeptin in pre-optic area (POA) and arcuate nucleus (ARC). Fluorescence microscopy was used to analyze the number of immunoreactive kisspeptin containing cell bodies (kp-ir), NPY-ir containing varicosities in close contact with kp10-ir cell bodies and dendrites, density of NPY containing fibers in the studied sites. Total of 3,037 kp10-ir cell bodies were analyzed, which 27% of them are in close contact with NPY containing axons. The mean number of axo-somatic contacts per kp10-ir neuron observed was 1.6 ± 0.3 and 2.1 ± 0.3 for POA and ARC, respectively. On the other hand, the mean number of NPY varicosities in close contact with kp10-ir dendrite was 1.5 ± 0.5 and 1.6 ± 0.1 contacts for POA and ARC, respectively. Thus, this study determined that NPY containing axons are in close contact with kisspeptin cell bodies and dendrites in POA and ARC of ovariectomized ewes with estradiol implant. It suggests that NPY may regulate neuroendocrine functions acting directly on kisspeptin neurons.