Effects of alpha-fluoromethylhistidine on locomotor activity, brain histamine and catecholamine contents in rats.

One hour after the intraperitoneal (i.p.) injection of FMH (200 mg/kg), locomotor activity and rearing were statistically reduced, by 3 hours later, only the locomotor activity was reduced in rats. The i.p. injection of FMH (100 and 200 mg/kg) had no effects on motor incoordination, blood pressure, heart rate and tetrabenazine-induced ptosis in rats. One and 3 hours after FMH injection, the histamine levels significantly decreased in the hypothalamus, cortex and thalamus, slightly in the olfactory bulb, amygdala, pons-medulla oblongata and midbrain, but very little in the striatum, hippocampus, cerebellum and pituitary. On the other hand, noradrenaline and dopamine levels were not affected in most of the regional parts, although in the cortex and midbrain, the dopamine levels were slightly reduced 1 hour after FMH (100 and 200 mg/kg). These data showed that central histamine may play an important role in the locomotor activity of rats.