Effects of peripheral blood polymorphonuclear leukocyte function and bloodcomponents in Japanese black steers administered ACTH in a cold environment

An examination of the effects of artificial stress induced by adrenocortico tropin (ACTH) on total and differential leukocyte counts, plasma cortisol l evels, metabolic profiles and peripheral blood polymorphonuclear leukocyte (PMN) function was performed on Japanese Black steers kept in a cold enviro nment, with the following regimes; 1) -5 degrees C . ACTH (100 IU/day for 3 days), 2) 0 degrees C ACTH, 3) 15 degrees C . ACTH and 4) 15 degrees C . P BS. Blood samples were collected before and at 1, 2, 24, 48, 72 and 96 hr p rior to the application of the stressor. The plasma cortisol level was foun d to greatly increase at one hr after the first treatment of ACTH, particul arly so in animals exposed to - 5 degrees C. Total leukocytes (- 5 degrees C and 0 degrees C experiments, respectively), the monocytes (- 5 degrees C) , neutrophils and eosinophils (- 5 degrees C, 0 degrees C and 15 degrees C, respectively) obviously increased just after the first administration, alt hough lymphocyte counts at -5 degrees C were inversely related to those des cribed above. All of these tendencies were augmented by the cold environmen t except for eosinophils. The chemiluminescent (CL) response of PMN decreas ed in the ACTH-administered steers at an early stage of post-administration , however, it tended to recover from the lower-than-base value in the cold- affected steers. ACTH administration resulted in higher plasma glucose (Glu ) compared to a control, although only steers housed at -5 degrees C eviden tly showed lower plasma inorganic phosphorus (IP). No abnormal serum acute phase protein, or immunosuppressor, was noted. ACTH thus appears not only t o promote physiological reactions but also to temporarily suppress PMN cell ular immune function in Japanese Blade steers. Although, a cold environment rapidly restored the CL activity to over the pre-administrational value, s uggesting that a vital response was activated by crymo-stimuli.