Participação da via alfa-2 adrenérgica no controle da secreção do hormônio do crescimento no período prépúbere em novilhas da raça Nelore

• Autor(a) principal: de Oliveira Santana Batista, Emiliana [UNESP]
• Data de Publicação: 2011
• Outros Autores: Cardoso, Daniel, de Paula Nogueira, Guilherme [UNESP]
• Tipo de documento: Artigo
• Idioma: eng; por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.revistas.usp.br/bjvras/article/view/34397; http://hdl.handle.net/11449/73011
• topic: Clonidine; GH; Nelore; Prepubertal

This study investigated GH secretion after clonidine (alpha-2 adrenergic agonist) treatment in pre-pubertal Nelore heifers. Clonidine (10 mg/kg, IV, 15 min samples for 4 h) was administrated in the same Nelore heifers at eight (n = 4), 12 (n = 5) and 15 (n = 4) months of age. The GH concentration was measured by radioimmunoassay (sensivity = 0.25 ng/mL, CV = 16%). At eight months, clonidine increased GH average concentration, total area of peaks, the total area of GH secretion and increased peak amplitude and reduced time to onset of peak (P < 0.05). At 15 months, the administration of clonidine increased the GH average concentration and at 12 months the increased occurred only in restricted intervals (P < 0.05). Clonidine injection stimulated GH secretion in prepubertal heifers and this effect was more evident in Nelore heifers at eight months compared to 12 and 15 months of age.