Marcatura retrograda selettiva con D-$\left[^{3}H\right]$ Aspartato dei neuroni delle proiezioni cortico-corticali destinate all'area SI

Barbaresi, Paolo ; Fabri, Mara ; Conti, Fiorenzo ; Manzoni, Tullio

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 81 (1987) no. 4, pp. 433-438

Résumé

A solution of D-$\left[^{3}H\right]$Aspartate mixed with horseradish peroxidase (HRP) was injected in the trunk and forelimb representation zones of area SI. Neurones labelled with D-$\left[^{3}H\right]$Aspartate were absent from the thalamus ipsilateral to the injected areas, but numerous neurones retrogradely labelled with this radioactive marker were present in the ipsilateral area SII (SII-SI associative neurones) and in the contralateral area SI (SI-SI callosal neurones). In both areas, cells labelled with silver grains were topographically distributed in the same regions containing cells retrogradely labelled with HRP. Associative and callosal neurones retrogradely labelled with D-$\left[^{3}H\right]$Aspartate showed a laminar pattern similar to that of associative and callosal neurones labelled with HRP, with one exception. In the inner half of layer III, associative and callosal neurones labelled with D-$\left[^{3}H\right]$Aspartate were much less numerous than those labelled with HRP. The present results indicate that D-$\left[^{3}H\right]$Aspartate is a selective tracer for a high proportion of associative and callosal neurones of areas SI and SII. These labelled neurones therefore are likely to use Aspartate and/or Glutamate as neurotransmitter. The reasons by which cortico-cortical neurons of lower layer III were unlabelled remain unsolved. These neurones might utilize different chemical(s) as neurotransmitter(s) or, alternatively, they might represent a case of phalse negativity.