THE AGE-RELATED INCREASE IN GALANIN BINDING-SITES IN THE RAT-BRAIN CORRELATES WITH BEHAVIORAL IMPAIRMENT

The regional distribution of [(125)]galanin specific binding sites was determined in young (three-to four-month-old), 14-15-month-old and ag ed (26-27-month-old) male Sprague-Dawrey rats, previously tested for t heir performances in the Morris water-maze task, using the radioautogr aphic method on brain sections. A significant increase in specific bin ding was observed in piriform and entorhinal cortex, ventral subiculum , and dorsal dentate gyrus in the aged rats, whereas no significant ch anges were observed in dorsal subiculum, amygdala, septal area and var ious subcortical structures. The area-specific regional increase in sp ecific binding density in aged rats was significantly correlated with the impairment of the behavioral performance in the Morris water-maze task. The change in [I-125]galanin specific binding was a result of an increase in the number of galanin binding sites, but not of an increa se in affinity.