REGENERATION OF NOREPINEPHRINE-CONTAINING FIBERS IN OCCIPITAL CORTEX OF ADULT CATS

Regeneration of norepinephrine (NE)-containing nerve fibers in occipit al cortex of adult cats was studied using morphological and biochemica l methods. Initially, degeneration of cortical NE fibers was induced b y direct infusion of 6-hydroxydopamine (6-OHDA) for a week. Cortical r einnervation by NE fibers continuously proceeded throughout 52 weeks, the longest survival period studied, after stopping 6-OHDA infusion. T he rate of the reinnervation was slower in mature cortex than that obt ained earlier in immature cortex, The present results indicate that th e regenerative ability of the central NE neurons is universal, not lim ited to the immature brain. It is implied that the central NE neurons are equipped with a transmitter-specific repair mechanism throughout l ife.