Distribution of the transcription factor Signal Transducer and Activator of Transcription 3 in the rat central nervous system and dorsal root ganglia

Signal Transducer and Activator of Transcription 3 (STAT3) is a transcripti on factor that acts as an intracellular signalling molecule after receptor activation by several cytokines, e.g., interleukin-6, leptin and ciliary ne urotrophic factor. We have investigated the localization of STAT3 in the ra t central nervous system and dorsal root ganglia. Light microscopic immunoh istochemistry showed that STAT3-Like immunoreactivity (STAT3-LI) was presen t in the nucleus and cytoplasm of neurons. STAT3-LI was seen both in cell b odies and in proximal and distal dendrites. Many structures involved in mot or functions, such as the ventral horn of the spinal cord, the motor crania l nerve nuclei, the red nucleus and the Purkinje cells of the cerebellum sh owed STAT3-LI. STAT3-LI was also present in many regions involved in autono mic regulation, such as the intermediolateral cell column of the spinal cor d, the nucleus of the solitary tract, the dorsal motor nucleus of the vagus nerve, the area postrema, the locus coeruleus, the Banington's nucleus and the arcuate, the lateral, the dorsomedial, the ventromedial, and the parav entricular hypothalamic nuclei. Other structures showing STATS-LI were the dorsal root ganglia, the thalamus (the anterodorsal and paraventricular nuc leus), the cerebral neocortex (layer 5) and the olfactory bulb. The wide di stribution of STAT3-LI in the nervous system is consistent with reports of cytokine actions in the brain, but the present findings further suggest nov el roles for STAT3 in mediating influences of cytokines on specific neurona l circuits regulating motor, sensory and autonomic functions. (C) 2000 Else vier Science B.V. All rights reserved.