The age-related increase in galanin binding sites in the rat brain correlates with behavioral impairment

The regional distribution of [125I]galanin specific binding sites was determined in young (three- to four-month-old), 14-15-month-old and aged (26-27-month-old) male Sprague-Dawley rats, previously tested for their performances in the Morris water-maze task, using the radioautographic method on brain sections. A significant increase in specific binding was observed in piriform and entorhinal cortex, ventral subiculum, and dorsal dentate gyrus in the aged rats, whereas no significant changes were observed in dorsal subiculum, amygdala, septal area and various subcortical structures. The area-specific regional increase in specific binding density in aged rats was significantly correlated with the impairment of the behavioral performance in the Morris water-maze task. The change in [125I]galanin specific binding was a result of an increase in the number of galanin binding sites, but not of an increase in affinity.