FETAL, NEONATAL AND ADULT EXPRESSION OF BENZODIAZEPINE RECEPTOR SUBTYPES IN HUMAN VISUAL-CORTEX

We have investigated the relative distributions of type I and type II benzodiazepine receptors in fetal, neonatal and adult human visual cor tex using [H-3]flunitrazepam and the triazolopyridazine, CL218872. Mic rodensitometry of autoradiograms show that while both benzodiazepine s ubtypes are found in visual area 17 early in life, the type II benzodi azepine receptors predominate. In adult human visual cortex comparable mounts of type I and type II subtypes occur in a laminar specific dis tribution concentrated in layers 4c and 2/3. The results may suggest a role for age-dependent expression of benzodiazepine receptor subtypes in visual cortex development and neuroplasticity.