Brain 3-methyoxytyramine varies inversely with blood glucose in decapitated rats

Concentrations of the dopamine metabolite, 3-methyoxytyramine, were decreased significantly in the corpus striatum and nucleus accumbens of rats 30 min after the IP injection of D-glucose (2 g/kg). Conversely, 90 min after the administration of regular insulin (6 U/kg), significant increases in the concentrations of 3-methoxytyramine were observed in these two brain regions. Brain levels of the major metabolites of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid, did not correlate well with blood glucose concentration. The significant negative correlation of blood glucose with striatal and accumbens 3-methoxytyramine suggests an inverse relationship between dopamine metabolism and blood glucose concentration, that may be secondary to decapitation-induced anoxia.