The influence of stress on early pregnancy in the pig

Abstract

The manifestations of stress, defined as disturbances of homeostasis, are commonly linked to enhanced activity of the hypothalamo-pituitary-adrenal (HPA) axis and the activation of the sympathetic adreno-medullary (SA) system. Activation of the HPA system results in the secretion of peptides from the hypothalamus, principally corticotropin releasing hormone (CRH), which stimulate the release of β-endorphin and adrenocorticotropic hormone (ACTH) from the hypothalamus and pituitary. ACTH induces the secretion of corticosteroids from the adrenal cortex, which can be seen in pigs exposed to acute physical and/or psychological stressors. Stress is considered to be associated with a decrease in reproductive functions. The causes of extreme stress may include new social grouping, food deprivation and poor thermoregulation. A brief review is given on current knowledge of these stressors and their impact on early pregnancy in the pig.