The effects of inhibitors of energy metabolism on the growth of one-cell rabbit ova to blastocysts in vitro

Abstract

Fertilized 1-cell rabbit ova were cultured in the presence of 3 oxidative phosphorylation inhibitors (cyanide, 2,4-dinitrophenol and oligomycin), 2 tricarboxylic acid (TCA) cycle inhibitors (malonate and fluoroacetate) and 1 glycolytic inhibitor (2-deoxyglucose). All 3 oxidative phosphorylation inhibitors killed ova at the 1-cell stage and the damage caused by each was similar. Malonate was non-toxic at all concentrations whereas some concentrations of fluoroacetate stopped growth at the 1-cell stage. This toxic effect could, in some circumstances, be reversed by the presence of acetate but not of glucose. The transition from morula to blastocyst was blocked by 2-deoxyglucose, and this was prevented by the addition of glucose to the medium; pyruvate, ribose, glycerol and L-.alpha.-glycerol phosphate were ineffective. An active oxidative phosphorylation system and tricarboxylic cycle appear to be present and essential in the rabbit embryo from the 1-cell stage, but glycolysis may not be essential until blastocyst formation.