A glutamatergic innervation of the nucleus basalis/substantia innominata

The possibility of there being a glutamatergic innervation of the nucleus basalis/substantia innominata, was investigated in the rat. High affinity glutamate uptake, and a calcium-dependent, potassium-evoked release of endogenous glutamate in this tissue, were demonstrated. In contrast to the striatum, however (which is known to receive a major, probably glutamatergic, corticofugal input), removal of the fronto-parietal cortex failed to modify these parameters. Thus, while the nucleus basalis/substantia innominata appears to possess an important glutamatergic innervation, its origins are as yet unknown. The existence of such an innervation, however, may be of relevance for the degeneration in Alzheimer's disease of the magno-cellular cholinergic neurones, which show a particular sensitivity to excitotoxic agents.