Long-lasting peripheral and central effects of 6-hydroxydopamine in rats.

1. In newborn rats treated with 6-hydroxydopamine hydrobromide (6-OHDA) (50-150 mg/kg on 5-7 days) a widespread and long-lasting dose related sympathectomy was demonstrated.2. When rats given 6-hydroxydopamine (100 mg/kg, seven treatments) in the neonatal period were killed at 10 weeks the concentration of noradrenaline (NA) in the heart, mesentery and vas deferens was significantly reduced. There was no alteration in the catecholamine content of the adrenal glands.3. The amplitude of the responses of perfused mesenteric arteries from 6-hydroxydopamine treated rats to intra-arterial noradrenaline was not increased, compared with controls, but the duration of responses was increased.4. 6-Hydroxydopamine given to newborn rats caused a long-lasting depletion of noradrenaline in three of the five regions of the central nervous system (cortex, cerebellum and spinal cord) studied. The concentration of noradrenaline in the pons-medulla was increased, but in the thalamic region was unchanged. The treated rats showed significantly lower exploratory activity.5. Treatment of newborn rats with 6-hydroxydopamine thus has striking and long-lasting effects on peripheral and central adrenergic systems.