EXPERIMENTAL HYPERTHYROIDISM ENHANCES THE REGENERATION OF CENTRAL NEURITES PROMOTED BY PERIPHERAL-NERVE GRAFTS IN THE HIPPOCAMPUS

The aim of the present paper was to ascertain whether experimental hyp erthyroidism promotes the regenerative action of predegenerated periph eral nerve grafts implanted into the transected hippocampus. Hyperthyr oidism was induced by subcutaneous injections of T-4. Autologous perip heral nerve grafts were implanted immediately, 7 and 35 days following transection of the sciatic nerve. Cells extending their neurites into the grafts were traced by means of horseradish peroxidase conjugated with fluoresceine isothiocyanate (FITC-HRP). Fluorescence microscope e xamination revealed that experimentally induced hyperthyroidism consid erably enhanced the regenerative influence of peripheral nerve grafts. This effect was particularly pronounced in hyperthyrotic animals trea ted with either nonpredegenerated or 35 day predegenerated nerve graft s.