Pyruvate infusions into the septal area attenuate spontaneous alternation impairments induced by intraseptal morphine injections.

Glucose infusions into the medial septal area attenuate memory impairments produced by concurrent intraseptal morphine injections. One possible explanation for these effects of glucose on memory is that the treatment modulates regional energy metabolism. As a test of this hypothesis, the present experiment determined whether intraseptal pyruvate injections could attenuate a spontaneous alternation impairment seen after intraseptal morphine injections. Intraseptal injections of morphine (4.0 nmol) 30 min prior to testing produced spontaneous alternation scores significantly lower than those in control groups. Morphine injections near, but outside, the septal region did not impair spontaneous alternation performance. The morphine-induced impairment was similarly reversed by coadministration of either glucose (18 nmol) or pyruvate (18 nmol) into the septum. These findings suggest that glucose may act through the tricarboxylic acid cycle by increasing the availability of ATP, augmenting the synthesis of certain neurotransmitters, or both.