AGE-RELATED DECREASE IN THE DENSITY OF BENZODIAZEPINE RECOGNITION SITES IN THE BRAIN OF THE FRESH-WATER EEL (ANGUILLA-ANGUILLA)

The binding parameters of benzodiazepine receptors labeled with [H-3]flunitrazepam were investigated in the brain of male adult eels at the trophic phase (4 years old) and of male silver eels (6 year old ocean migrants). The density of [H-3]flunitrazepam binding sites was significantly decreased (-26%) in the brain of silver eels compared with younger counterparts. In contrast, the apparent dissociation constant (K(d)) was not significantly different in the two experimental groups. These results are discussed in terms of the possible involvement of stress, behavioral and environmental factors and age-related degenerative processes.