Behavioral effects of norepinephrine and dibutyryl 3',5'AMP in centrally sympathectomized rats

Male Wistar rats were injected intraventricularly with two doses of 250 μg of 6-hydroxydopamine (6-OHDA) at a 48 hr interval. Seven days after the second injection, 50 μg of norepinephrine (NE) or 100 μg of dibutyryl cyclic AMP (DCAMP) were injected intraventricularly. There were no differences in gross behavior but an increase in irritability was observed in rats treated with 6-OHDA compared with controls. NE increased locomotor activity and irritability of animals. Chemical sympathectomy intensified locomotor excitation and irratibility caused by NE. DCAMO caused an increase of locomotor activity, irritability and convulsions 30 min after injection. These behavioral phenomena were intensified in animals treated with 6-OHDA. It is suggested that 6-OHDA sensitizes the central nervous system to action of NE and DCAMP.