Milk yield in Saanen goats: relationships between milk synthesis, stress, apoptosis and gene expression in mammary gland

• Grant number: 18/09093-5
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2018
• End date: October 31, 2020
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Production
• Principal Investigator: João Alberto Negrão
• Grantee: João Alberto Negrão
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil

Abstract

The decreasing of milk yield caused by stress has been related to cellular changes and apoptosis in the mammary gland, modulated by action cortisol, insulin, prolactin (PRL), growth hormone (GH) and insulin-like growth factor 1 (IGF-1). By other way, some authors suggest that chaperones can interact with the cellular receptors of cortisol, PRL, GH, insulin and IGF-1 in other tissues, playing a fundamental role in the maintenance of cellular homeostasis, protecting the cells of different stressors. However, the interactions between chaperones of family of the heat chock proteins, HSPs), cortisol, PRL, GH, insulin, IGF-1 and, cell proliferation and apoptosis in the mammary gland were not found in the literature. In this context, 40 lactating Saanen goats will be used to study the effect of stress on milk synthesis, apoptosis and gene expression in the mammary gland in vivo (Experiment I) and in vitro (Experiment II). In the in vivo experiment, the relationship between stress, cortisol release and mammary epithelial cells will be evaluated after administration of ACTH (standard physiological stress) or physiological (control) solution. In the in vitro experiment will be evaluated, the effect of different concentrations of cortisol (0, 10, 100 and 1000 ¼g / mL) in mammary epithelial cells. In vivo will be analyzed the effect of stress on milk production and quality, cortisol and glucose release, proliferation and cellular apoptosis rates, expression of the receptors of cortisol (GR and MR), PRL (PRLR), GH ), insulin (INSR), (IGF1R), HSPs 60, 70 and 90. In vitro will be analysed the effect of cortisol on synthesis of lactose, casein, lactalbumin and lactoferrin in cell culture, and expression of PRLR, GHR, INSR, IGF1R, GR, MR, HSPs 60, 70, 90, proliferation rates and apoptosis in mammary epithelial cells. Data obtained from this present project will be important tool in the study the effect of stress on the persistence of lactation. (AU)