Neuroendocrine mechanisms of central CRH and stress-induced behavior and immune changes



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Texas Tech University


Previous work in both pigs and rodents showed that central corticotropin releasing hormone (CRH) had a profound effect on behavior and immunity. CRH given in the lateral ventricle has a great effect on behavior, Cortisol concentration lymphocyte proliferation and leukocyte distributions in freely-moving pigs. The specific objective of this work was to describe the dose response relationships for behavioral and immune effects. Pigs were fitted with an icv cannula in the lateral ventricle and with a vena cava catheter for remote blood collections. Pigs were continuously video taped during the work. Pigs weighing about 20 kg were given no injection, saline, or saline containing 0.5, 5, 50 or 150 µg porcine CRH in pigs. Pigs' behavioral responses showed a significant dose-response to CRH for oral-nasal behavior and general activity. Peak increases in behavioral activation were found at 50 µg. Sequences of behaviors were seen to change with dose of CRH. Sequences of locomotor activity increased and maintenance behaviors decreased with CRH, whereas the sequence of behaviors in saline animals remained complex. Numbers of circulating leukocytes did not change over the range of doses of CRH examined. In conclusion, behavioral effects of central CRH were sensitive at a much lower dose than were immune changes and the behavioral response to icv CRH was dose dependent.