Implants for sustained drug release over the somatosensory cortex of the newborn rat: A comparison of materials and surgical procedures

Drugs that interfere with neural transmission are an important tool to assess the role of specific neurotransmitters in the development of the nervous system. Systemic drug treatments often produce neurodevelopmental effects with questionable specificity. Furthermore, many compounds of interest do not cross the blood-brain barrier. To overcome these limitations, either elvax or gelfoam implants have been previously employed to produce sustained drug release over specific brain regions. In this paper, stereotaxic coordinates are provided for reproducible insertion of drug-delivery systems over the rat somatosensory cortex at birth (P0), prior to the appearance of the cortical barrel pattern; a novel and simpler method for preparation of elvax 40p sheets is described; a new implantation technique is provided. Furthermore, we compare the efficiency and tolerability of elvax vs gelfoam implants, showing that gelfoam, but not elvax, significantly disrupts cortical cytoarchitecture. Finally, successful destruction of serotonin-containing terminals in layer IV of the primary somatosensory cortex of the newborn rat is demonstrated by application of parachloroamphetamine-containing elvax implants.