Influence of exogenous triiodothyronine on axonal regeneration and wound healing in the brain of the rat

Rats with parasagittal incised wounds of the telencephalon were treated for 1, 7, 21 or 56 days with triiodothyronine (T₃), 0.5 μg/100 g body weight, injected once daily. Controls were injected with the aqueous solution in which the T₃ was dissolved. The brains were examined histologically and quantitative assessments were made of the regeneration of axons into and across the lesions and of the healing of the wounds. T₃, when administered over an 8-week period, stimulated axonal regeneration in the dorsal cortex and corpus callosum and promoted healing of the wound in the corpus callosum. The results of this investigation suggest that the use of T₃ in the clinical treatment of injury to the central nervous system may be of less value than the work of earlier authors had indicated.