In several species, adult metabolic phenotype is influenced by the intrauterine environment, often in a sex-linked manner. In horses, there is also a window of susceptibility to programming immediately after birth but whether adult glucose-insulin dynamics are altered by neonatal conditions remains unknown. Thus, this study investigated the effects of birth weight, sex and neonatal glucocorticoid overexposure on glucose-insulin dynamics of young adult horses. For the first 5 days after birth, term foals were treated with saline as a control or ACTH to raise cortisol levels to those of stressed neonates. At 1 and 2 years of age, insulin secretion and sensitivity were measured by exogenous glucose administration and hyperinsulinaemic-euglycamic clamp, respectively. Glucose-stimulated insulin secretion was less in males than females at both ages, although there were no sex-linked differences in glucose tolerance. Insulin sensitivity was greater in females than males at 1 but not 2 years of age. Birthweight was inversely related to the area under the glucose curve and positively correlated to insulin sensitivity at 2 but not 1 years of age. In contrast, neonatal glucocorticoid overexposure induced by ACTH treatment had no effect on whole body glucose tolerance, insulin secretion or insulin sensitivity at either age, although this treatment altered insulin receptor abundance in specific skeletal muscles of the 2 year old horses. These findings show that glucose-insulin dynamics in young adult horses are sexually dimorphic and determined by a combination of genetic and environmental factors acting during early life.
Valenzuela, OJellyman, JAllen, VHoldstock, NBForhead, AFowden, A
Faculty of Health and Life Sciences\Department of Biological and Medical Sciences
Year of publication: 2016Date of RADAR deposit: 2016-11-22
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