Meeting Abstract
Reduced reproduction and dietary restriction each increase lifespan in many animals. Reducing reproduction decreases dietary intake, and dietary restriction similarly reduces reproductive output. This has led to the widespread view that both treatments extend lifespan by overlapping physiological mechanisms. Work in C. elegans and mice suggests that long-lived animals have greater turnover of lipids. Hence, we measured nutrient oxidation in lubber grasshoppers. Four treatment groups were used: sham-operated & full diet (Sham-FD), ovariectomized & full diet (OVX-FD), sham-operated & dietary restricted (Sham-DR), and ovariectomized & dietary restricted (OVX-DR). Ovariectomy reduces feeding rate about 30%, and the Sham-DR group was fed the same daily amount as that consumed by the OVX-FD group. Exogenous nutrient oxidation was tested by feeding each individual one 13C-labeled metabolic tracer (glucose, leucine, or oleic acid). Breath samples were collected hourly and tested for 1313C content, which reflected nutrient oxidization during sampling. Glucose metabolism was highest in Sham-FD and lowest in OVX-FD. Dietary restriction increased leucine metabolism, whereas ovariectomy delayed leucine metabolism, with peak longer after ingestion. OVX-FD and Sham-DR animals with matched feeding had distinct profiles of leucine metabolism. Oleic acid metabolism was not affected treatment. In contrast to prior studies, our results suggest that highly reproductive animals metabolize more sugar, while minimally reproductive animals metabolize more amino acid. Oxidation of amino acids may be more important in life-extension than previously thought, especially for phytophagous animals.
