Destruction of a sub-population of cortical neurones by suicide transport of volkensin, a lectin from Adenia volkensii.

A method for the destruction of a sub-population of neocortical pyramidal neurones is described. The technique uses unilateral striatal injections of volkensin, a toxic lectin from Adenia volkensii, which undergoes retrograde axonal transport from the site of injection to destroy subcortically projecting pyramidal cells within the neocortex. Striatal volkensin injections produce a significant reduction in the number of large pyramidal neurones of the infragranular layer. The selectivity of the lesion was demonstrated by the preservation of glutamic acid decarboxylase mRNA positive cells, considered to be cortical interneurones within ipsilateral cortex. The binding of the serotonin 1A receptor agonist [3H]-8-hydroxy-2-(n-dipropylamino)tetralin, visualised by autoradiography, was reduced in areas showing loss of large cells, indicating that these receptors may be present on subcortically projecting pyramidal cells. Ricin, another toxin lectin, but effective as a suicide transport agent in only the peripheral nervous system, produced local striatal damage but no cortical cell loss. The selective destruction by volkensin of neocortical pyramidal neurones with subcortical projection targets should aid the neurobiological investigation of such cells. Additionally, data obtained using this technique may provide insights into the interpretation of biochemical findings in neurodegenerative disease in which pyramidal cell loss is a significant feature.