title: Synaptosomal lactate dehydrogenase isoenzyme composition is shifted toward aerobic forms in primate brain evolution.
abstract: With the evolution of a relatively large brain size in haplorhine primates (i.e. tarsiers, monkeys, apes, and humans), there have been associated changes in the molecular machinery that delivers energy to the neocortex. Here we investigated variation in lactate dehydrogenase (LDH) expression and isoenzyme composition of the neocortex and striatum in primates using quantitative Western blotting and isoenzyme analysis of total homogenates and synaptosomal fractions. Analysis of isoform expression revealed that LDH in synaptosomal fractions from both forebrain regions shifted towards a predominance of the heart-type, aerobic isoform LDH-B among haplorhines as compared to strepsirrhines (i.e. lorises and lemurs), while in the total homogenate of the neocortex and striatum there was no significant difference in LDH isoenzyme composition between the primate suborders. The largest increase occurred in synapse-associated LDH-B expression in the neocortex, with an especially remarkable elevation in the ratio of LDH-B/LDH-A in humans. The phylogenetic variation in the ratio of LDH-B/LDH-A was correlated with species-typical brain mass but not the encephalization quotient. A significant LDH-B increase in the subneuronal fraction from haplorhine neocortex and striatum suggests a relatively higher rate of aerobic glycolysis that is linked to synaptosomal mitochondrial metabolism. Our results indicate that there is a differential composition of LDH isoenzymes and metabolism in synaptic terminals that evolved in primates to meet increased energy requirements in association with brain enlargement.
authors.affiliation: Department of Anthropology, The George Washington University, Washington, D.C., USA.
authors.forename: Tetyana
authors.initials: T
authors.lastname: Duka
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Anderson
authors.forename: Zachary
authors.initials: Z
authors.lastname: Collins
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Raghanti
authors.forename: John J
authors.initials: JJ
authors.lastname: Ely
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Hof
authors.forename: Derek E
authors.initials: DE
authors.lastname: Wildman
authors.forename: Morris
authors.initials: M
authors.lastname: Goodman
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Grossman
authors.forename: Chet C
authors.initials: CC
authors.lastname: Sherwood
mesh_terms: D000368:Aged; D000818:Animals; D005075:Biological Evolution; D003342:Corpus Striatum / Q000033:anatomy & histology / Q000201:enzymology*; D005260:Female; D006801:Humans / Q000033:anatomy & histology / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D000080864:Lactate Dehydrogenase 5; D045022:Lactate Dehydrogenases / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D019579:Neocortex / Q000033:anatomy & histology / Q000201:enzymology*; D009929:Organ Size; D010802:Phylogeny; D017729:Presynaptic Terminals / Q000201:enzymology; D011323:Primates / Q000033:anatomy & histology / Q000378:metabolism*; D016548:Prosencephalon / Q000033:anatomy & histology / Q000201:enzymology; D013045:Species Specificity; D013574:Synaptosomes / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D045022:Lactate Dehydrogenases; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; C409667:lactate dehydrogenase 1