Lead Acutely Reduces Glucose Utilization in the Rat Brain Especially in Higher Auditory Centers

The 2-deoxyglucose autoradiographic method was used to assess the effects of acute lead exposure on regional brain glucose metabolism in the rat. Eight male Long-Evans hooded rats weighing between 317 and 364 g were cannulated for access to the femoral artery and vein, then given an iv bolus of lead acetate (27 mg Pb/kg as 50 mg PbAc/kg) or saline and observed for the six hours prior to the start of the 2-deoxyglucose experiment. Under controlled conditions of light and sound, the rats were injected with 14C-2-deoxyglucose, then sacrificed after 45 min. The brains were frozen in isopentane cooled to -40 degrees C and 20 micron sections were made. Every third slice was dried on glass slides and apposed to Kodak SB5 X-ray film for five days. Local cerebral metabolic rates (1CMRglu) were measured by densitometry with a computerized image analyzer. Four other rats were similarly given lead (but not 2-deoxyglucose), and blood samples taken at -1, 15 30, 60, 120, and 360 min had corresponding lead levels of 1.8 +/- 1.4, 156 +/- 14.6, 182 +/- 20.4, 155 +/- 17.4, 134 +/- 12.5 and 36 +/- 2.3 ppm. Whole brain lead was 0.45 +/- 0.22 and 1.20 +/- 0.15 ppm in the control and lead-treated groups, respectively (p less than 0.025). Significant reductions in 1CMRglu occurred in the following structures: medial geniculate bodies (15.6 +/- 2.5%), inferior colliculus (13.8 +/- 4.6%), and sensory cortex (9.8 +/- 1.8%). Among those structures showing the greatest percent reductions were several auditory centers, including lateral lemniscus (13.0 +/- 4.6%), auditory cortex (10.4 +/- 4.1%), and superior olivary complex (8.0 +/- 7.0%).(ABSTRACT TRUNCATED AT 250 WORDS)