Cerebral metabolism of glucose-3-C¹⁴, pyruvate-1-C¹⁴ and lactate-1-C¹⁴ in mental disease

¹ Research Facility, Rockland State Hospital, Orangeburg, New York

A previous investigation indicated that less brain CO₂ was derived from glucose in psychotic patients than in normal subjects and suggested pyruvate and/or lactate as the site(s) of dilution. In this report more direct determinations, using glucose-3-C¹⁴, pyruvate-1-C¹⁴, dl-lactate-1-C¹⁴, d-lactic-1-C¹⁴ and l-lactic-1-C¹⁴ acids as substrates, have corroborated the decreased cerebral oxidation of carbohydrate by chronic mental patients and indicated pyruvate as the metabolic level at which protein and/or lipid intermediate(s) caused increased dilution. After glucose-3-C¹⁴ injection 35% of brain CO₂ was derived from glucose in the mental patient and 54% in the normal subject. With pyruvate-1-C¹⁴ initial values for brain C¹⁴O₂ activities were lower in mental patients. Using dl-lactate-1-C¹⁴ over-all body metabolism was reduced in psychotics, whereas brain catabolism was similar to that of normal subjects. Cerebral oxidation of d-lactic-1-C¹⁴ acid was greater in mental patients although over-all body metabolism showed little difference from normal subjects. Using the l-isomer both body and brain catabolism were decreased in mental patients.