Effects of intracerebroventricular injection of α-fluoromethylhistidine on radial maze performance in rats

The effects of α-fluoromethylhistidine (α-FMH) on spatial cognition were investigated using the eight-arm radial maze paradigm in rats. Intracerebroventricular (ICV) injection of α-FMH resulted in spatial memory deficits characterized by an increase in the number of total errors (TE) and a decrease in the number of initial correct responses (ICR). There was a strong correlation between increases in the number of TE and decreases in histamine contents of the cortex and hippocampus regions of the brain, which are known to participate in learning and memory. On the other hand, both histamine (50-100 ng, ICV) and thioperamide (10 μg, ICV) significantly ameliorated the memory deficit induced by α-FMH. However, metoprine showed no significant effect on the α-FMH-induced memory deficit. Pyrilamine and R-(α)-methylhistamine enhanced the memory deficit induced by α-FMH, at doses that had no appreciable effect when administered alone. In contrast, no significant influence on α-FMH-induced memory deficit was observed with zolantidine. Copyright (C) 1999 Elsevier Science Inc.