Aspartato come neurotrasmettitore delle proiezioni claustro-corticali nel gatto

Fabri, Mara ; Barbaresi, Paolo ; 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. 439-446

Résumé

Several anatomical studies showed that the dorsal portion of the claustrum sends diffuse projections to several neocortical areas, including the first (SI) and the second (SII) somatosensory areas. However, no data are available concerning the neurotransmitters utilized by claustro-cortical neurones. In this paper are described the results of experiments showing that in the Cat claustral neurones projecting to areas SI and SII probably utilize the amino acids Aspartate and/or Glutamate as neurotransmitter. In these experiments the autoradiographic technique based on the retrograde axonal transport of tritiated D-Aspartate (D-$\left[^{3}H\right]$Asp) was employed. It is known that this radioactive substance: i) is taken up selectively by axon terminals of neurones which utilize excitatory amino acids as neurotransmitter, ii) is retrogradely transported, iii) is not metabolized and, iv) accumulated in perikarya. D-$\left[^{3}H\right]$Asp was injected, mixed with HRP, in the trunk and forepaw zones of SI (3 cats) or in the forepaw zone of SII (5 cats). Another group of animals received injections of HRP alone in the same zones of SI (3 cats) or SII (3 cats). In all cats in which D-$\left[^{3}H\right]$Asp was injected either in SI or SII, neurones retrogradely labelled with the tritiated marker were present in the dorsal portion of ipsilateral claustrum, all located in the central third of the nucleus. The topographical distribution of these labelled neurones matched that of HRP-labelled neurones. The present results show that claustral neurones projecting to ipsilateral somatosensory areas can be retrogradely labelled by tritiated D-Aspartate and they probably use the excitatory amino acids Aspartate and/or Glutamate as neurotransmitter.