Transport stress modulates adrenocorticotropin secretion from peripheral bovine lymphocytes

The influence of transport stress on the secretion of adrenocorticotropin ( ACTH) from peripheral bovine lymphocytes was evaluated by exposing cows to short- (30 min) or long-term (14 h) transport. After transporting animals f or 14 h they were given a mandatory rest for 24 h in two different situatio ns, either by off-loading them and allowing them to rest in a stall or by k eeping them in the truck. Blood samples were withdrawn before and after tra nsport and after the rest period in long-term transported cows and before a nd after transport in cows transported for 30 min. Peripheral blood lymphoc ytes were separated and cultured for 72 h in serum-free medium. Adrenocorti cotropin was measured using highly sensitive and specific immunoradiometric assay in culture supernates. We noticed no effect of short-term transport on ACTH secretion from lymphocytes. The ACTH concentration in animals trans ported for 14 h increased (P less than or equal to 0.01) from 4.72 +/- 0.48 pg mL(-1)/2 x 10(6) lymphocytes before the transport to 8.24 +/- 1.40 pg m L(-1) directly after the transport. When animals were off-loaded and rested in a stall for 24 h, ACTH secretion from cultured lymphocytes returned to the basal value of 4.24 +/- 0.31 pg mL(-1), whereas the animals rested in t he truck had ACTH levels of 8.9 +/- 1.43 pg mL(-1). Phytohemagglutinin, a p lant lectin that stimulates lymphocytes, did not affect the lymphocytic ACT H secretion in this study. Heart rate and rectal temperature measured telem etrically increased in cows directly after 14 h of transport but decreased to pre-transport values in cows rested for 24 h in cows rested in stalls an d those rested inside the truck. This experiment is the first to show lymph ocytic ACTH secretion in cows, and the results indicate that ACTH secretion from peripheral lymphocytes could be used as a reliable measurement in str ess studies.