Expression of corticotropin-releasing factor in the peripheral nervous system of the rat

THE occurrence and distribution of corticotropin-releasing factor (CRF) in the rat peripheral nervous system was studied by immunohistochemistry. CRF-positive nerve fibers were identified in the spleen, thymus, synovial membrane of the knee joint and adrenal gland. In general, CRF-positive fibers were seen predominantly in and around the blood vessels; however, many non-vascular thin varicose fibers were also observed. The neuronal character of the immunoreactive fibers was confirmed by staining consecutive tissue sections with a general neuronal marker, protein gene product 9.5. The finding of CRF-positive nerve fibers in the periphery demonstrates a strong anatomical link between the nervous, endocrine and immune systems, and may have pathophysiological implications in the inflammatory and stress-related disorders.