The anticonvulsant valproic acid concentrates in the olfactory bulb: selective laminar localization

Using autoradiography, we examined the distribution of radiolabel in the brain after intravenous administration of a tracer dose of [14C]valproic acid (VPA) into the anesthetized rat. The label was concentrated in the medial and dorsal portions of the olfactory bulb (highest levels in the glomerular layer) with almost no label elsewhere in the brain. The VPA seems to be a marker of a hitherto unrecognized spatial organization within the olfactory bulb. This unusual distribution of VPA may have a bearing on its anticonvulsant action.