Contribution of adrenomedullin to homeostatic response to cold stress in rat model

Acute stress known to stimulate sympathetic activity as well as the hypothalamo-pituitary–adrenal (HPA) axis, produces a significant increase in adrenomedullin (ADM) levels in the pituitary gland, plasma and adrenal glands, all of which are key components of HPA axis, suggesting a regulatory or protective role for ADM in countering HPA activation following a variety of physiological and psychological stressors. This study was conducted to assess a rat model for in depth investigation of biochemical mechanisms and consequences of cold stress. Four groups of Sprague–Dawley rats were observed for their serum total protein, glucose, trigliceride and cholesterol levels as well as their blood pressures after housing at room temperature, administration of ADM (1.0 nm/kg), exposing to cold stress (8 °C for 48 h) and exposing to ADM injection in addition to cold stress. The results suggest that application of ADM in addition to cold stress may act via receptors on different end-organs and causes altered metabolic regulation taking partial or total occupation of ADM receptors, stimulated in response to cold application induced physiologic ADM release before pharmacological ADM administration.