DIFFERENTIAL FOS EXPRESSION INDUCED BY IL-1-BETA AND IL-6 IN RAT HYPOTHALAMUS AND PITUITARY-GLAND

IL-1 beta has been implicated in central nervous system effects, inclu ding activation of the hypothalamic-pituitary-adrenal axis. Less is kn own concerning the role of IL-6 in brain. To compare and contrast IL-1 beta and IL-6 effects on brain, rats were administered intraperitonea l injections of IL-1 beta, IL-6 or control vehicle (3-8 mu g/rat), per fused 150-180 min post-injection, and brains and pituitaries were proc essed for Fos immunolabeling. IL-1 beta induced Fos expression in cort icotrophin-releasing factor (CRF) neurons of paraventricular nucleus ( PVN) of the hypothalamus, and anterior pituitary gland. IL-6 also indu ced immunolabeled Fos in the anterior pituitary gland, however, it did not induce Fos expression in CRF neurons of PVN. Data suggest that IL -6 may directly activate the anterior pituitary gland, whereas IL-1 be ta may exert its effect on the pituitary directly and/or indirectly vi a activation of CRF neurons in the PVN.