Abstract
-The CA1 and CA4/area dentata subfields of the hippocampus in young, mature and old rats were examined for age-related change in propyl β-carboline-3-carboxylate (PrCC) binding. 3H-PrCC bound with high affinity (Kd=0.82 nM) to one binding site when ethyl β-carboline-3-carboxylate was used to delineate specific binding. An age dependent change in the maximum number of 3H-PrCC binding sites in the CA1 and CA4/area dentate subfields of the hippocampus were assessed by using a saturating (6 nM) concentration of 3H-PrCC. Although 3H-PrCC specific binding at a saturating concentration (6 nM) was significantly less in both the CA1 and CA4/area dentata subfields of the senescent rat, the magnitude of the decrease was greater in the CA1 region. In addition, the affinity of the 3H-PrCC binding site in both subfields probably did not vary significantly with age. Therefore, the CA1 and CA4/area dentate of the rat hippocampus may not only lose BZ1 receptors or the BZ1 receptors conformation with age, but the severity of receptor or receptor conformation loss varies with the subfield.