The effects of N-methyl-D-aspartate antagonist 2-amino-7-phosphonoheptanoic acid microinfusions into the adult male rat substantia nigra pars reticulata are site-specific.

We examined the effects of regional infusions of 2-amino-7-phosphonoheptanoic acid (AP7) into the substantia nigra pars reticulata (SNR) in adult male rats on flurothyl-induced clonic seizures. AP7 infusions in the SNR had dose- and region-specific effects. In the SNR(anterior), both doses of AP7 (0.1 and 5 nmol) produced an anticonvulsant effect. In the SNR(posterior), the lower dose (0.1 nmol) did not influence the seizure threshold whereas the higher dose (5 nmol) of AP7 had a proconvulsant effect. The data indicate that there are two distinct regions within the SNR which differentially respond to pharmacological manipulations of the glutamatergic system. The region-specific effects in the SNR may provide an explanation for the previous conflicting reports regarding infusions of N-methyl-D-aspartate antagonists into this structure.