Stimulation of NMDA and AMPA receptors in the rat nucleus basalis of Meynert affects sleep

The nucleus basalis of Meynert (NBM), a heterogeneous area in the basal for ebrain involved in the modulation of sleep and wakefulness, is rich in glut amate receptors, and glutamatergic fibers represent an important part of th e input to this nucleus. With the use of unilateral infusions in the NBM, t he effects of two different glutamatergic subtype agonists, namely N-methyl -D-aspartic acid (NMDA and alpha-amino-3-hydroxy-5-methylisoxazole-4-propio nic acid (AMPA) hydrobromide, on sleep and wakefulness parameters were def; ermined in fi eely moving rats by means of polygraphic recordings. NMDA (5 nmol) and AMPA (0.4 nmol) induced an increase in wakefulness and an inhibit ion of slow-wave sleep. AMPA, but not NMDA, also caused a decrease in desyn chronized sleep. These AMPA- and NMDA-mediated effects were counteracted by a pretreatment with the specific NMDA antagonist 2-amino-5-phosphonopentan oic acid (20 nmol) and the specific AMPA antagonist 6,7-dinitroquinoxaline- 2,3-dione (2 nmol), respectively. The results reported here indicate that 1 ) the NBM activation of both NMDA and AMPA glutamate receptors exert a modu latory influence on sleep and wakefulness, and 2) AMPA, but not NMDA recept ors, are involved in the modulation of desynchronized sleep, suggesting a d ifferent role for NBM NMDA and non-NMDA receptors in sleep modulation.