Changes in mitochondrial energy utilization in young and old worker honeybees (Apis mellifera)

Trophocytes and fat cells in honeybees (Apis mellifera) have served as targets for cellular senescence studies, but mitochondrial energy utilization with advancing age in workers is unknown. In this study, mitochondrial energy utilization was evaluated in the trophocytes and fat cells of young and old workers reared in a field hive. The results showed that (1) mitochondrial density increased with advancing age; (2) mitochondrial membrane potential (δ Ψm), nicotinamide adenine dinucleotide oxidized form (NAD ⁺) concentration, adenosine triphosphate (ATP) concentration, and NAD⁺/nicotinamide adenine dinucleotide reduced form (NADH) ratio decreased with advancing age; and (3) the expression of NADH dehydrogenase 1 (ND1), ATP synthase, and voltage-dependent anion channel 1 (VDAC1) increased with advancing age, whereas ND1 and ATP synthase did not differ with advancing age after normalization to mitochondrial density and VDAC1. These results show that the trophocytes and fat cells of young workers have higher mitochondrial energy utilization efficiency than those of old workers and that aging results in a decline in mitochondrial energy utilization in the trophocytes and fat cells of worker honeybees.