I-125 labelled thyroid hormones in cultured mammalian nerve tissue

Summary Cultures of embryonic mouse and rat spinal cord-dorsal root ganglion combinations, and of newborn hamster and rat cerebellum were treated with 5×10^-6M I-¹²⁵ thyroxine and I-¹²⁵ triiodothyronine. Autoradiographic studies on glutaraldehyde-osmium tetroxide fixed tissue indicated that these hormones were located predominantly in neurons, but could be found in glia cells as well. This pattern was observed in cultures treated for 2 hours to 4 days. Some of the effects of thyroid hormones on the developing nervous system were therefore linked to a direct action of these hormones on nerve cells.Furthermore, the label was seen not only over the cytoplasm, as might be expected from past biochemical studies, but was also present over the nucleus, particularly the nucleolus. This suggested a possible role for these hormones in the process of translation.This work was supported by NIH Grant NB06735, The Nancy Louise Trynor Memorial Grant for Research on Multiple Sclerosis 433-D-10, and United States Public Health Service Grant No. NB-07849-02.Post-Doctoral Fellow, Department of Pathology, Yale University.Kennedy Scholar of the Rose F. Kennedy Center for Research in Mental Retardation and Human Development, New York.