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Studies in invertebrates have led to the identification of a number of genes that regulate lifespan, some of which encode components of the insulin or insulin-like signalling pathways. Examples include the related tyrosine kinase receptors InR (Drosophila melanogaster) and DAF-2 (Caenorhabditis elegans) that are homologues of the mammalian insulin-like(More)
During spring sheep do not normally ovulate but exposure to a ram can induce ovulation. In some ewes an LH surge is induced immediately after exposure to a ram thus raising questions about the control of this precocious LH surge. Our first aim was to determine the plasma concentrations of oestradiol (E2) E2 in anoestrous ewes before and after the "ram(More)
Mutations that decrease insulin-like growth factor (IGF) and growth hormone signaling limit body size and prolong lifespan in mice. In vertebrates, these somatotropic hormones are controlled by the neuroendocrine brain. Hormone-like regulations discovered in nematodes and flies suggest that IGF signals in the nervous system can determine lifespan, but it is(More)
BACKGROUND It is now widely accepted that AMP-activated protein kinase (AMPK) is a critical regulator of energy homeostasis. Recently, it has been shown to regulate circadian clocks. In seasonal breeding species such as sheep, the circadian clock controls the secretion of an endogenous rhythm of melatonin and, as a consequence, is probably involved in the(More)
Leucine acts as a signal nutrient in promoting protein synthesis in skeletal muscle and adipose tissue via mTOR pathway activation, and may be of interest in age-related sarcopenia. However, hyper-activation of mTOR/S6K1 has been suggested to inhibit the first steps of insulin signaling and finally promote insulin resistance. The impact of long-term dietary(More)
BACKGROUND Enterotoxigenic Escherichia coli (ETEC) infections result in large economic losses in the swine industry worldwide. ETEC infections cause pro-inflammatory responses in intestinal epithelial cells and subsequent diarrhea in pigs, leading to reduced growth rate and mortality. Administration of probiotics as feed additives displayed health benefits(More)
Characterization of the genetic defects causing gonadotropic deficiency has made a major contribution to elucidation of the fundamental role of Kisspeptins and Neurokinin B in puberty onset and reproduction. The absence of puberty may also reveal neurodevelopmental disorders caused by molecular defects in various cellular pathways. Investigations of these(More)
In mammals, IGFs are important for the proliferation and steroidogenesis of ovarian cells. Metformin is an insulin sensitizer molecule used for the treatment of the infertility of women with polycystic ovary syndrome. It is, however, unclear whether metformin acts on ovarian cells. Adenosine 5' monophosphate-activated protein kinase (AMPK) is involved in(More)
The tumor suppressor phosphatase and tensin homologue (PTEN) is involved in cell proliferation, adhesion, and apoptosis. PTEN overexpression in mammary epithelium leads to reduced cell number and impaired differentiation and secretion. In contrast, overexpression of the proto-oncogene Wnt-1 in mammary epithelium leads to mammary hyperplasia and subsequently(More)
The phosphatase PTEN regulates growth, adhesion, and apoptosis, among many other cell processes. To investigate its role during mouse mammary gland development, we generated MK-PTEN, a transgenic mouse model in which human PTEN is overexpressed in ductal and alveolar mammary epithelium during puberty, pregnancy, lactation, and involution. No obvious(More)