EFFECT OF ACUTE AND CHRONIC INFLAMMATION ON PLASMA GROWTH-HORMONE LEVELS IN RATS

We investigated the effect of acute and chronic stress on growth hormo ne (GH) plasma levels in fats. Acute stress was provoked by intravenou s administrations of lL-1 beta and TNF-alpha. Determinations were made at 10, 30, 60, 120 and 180 min following i.v. injection of these cyto kines into the caudal vein. We also investigated the chronic stress in duced by hind paw injections of Freund's adjuvant. Arthritis was devel oped by 21 days following such injection. GH levels were studied at 7, 14 and 21 days after induction of arthritis on several blood samples which were withdrawn from tail veins, and long-term hormonal profiles (3 hours' sampling) were determined at 12.00 am, 1.30 pm and 3.00 pm. Local administration of dexamethasone and the monoclonal antibody anti -ICAM-1 were also used in arthritic rats. Following acute stress, a si gnificant reduction of plasma GH levels has been evidenced, possibly r elated to the stimulation of corticotropin releasing hormone, Followin g chronic stress, we demonstrated a significant increase of GH levels, which were significantly reduced by dexamethasone treatment, and to a lesser extent by anti-ICAM-1 administration.