Meeting Abstract
P3.61 Monday, Jan. 6 15:30 Respiratory exchange ratios in grasshoppers upon life-extending dietary restriction or ovariectomy AWAN, A*; WILLIAMS, CM; HAHN, DA; HATLE, JD; Univ. of North Florida; Univ. of Florida; Univ. of Florida; Univ. of North Florida jhatle@unf.edu
Reduced reproduction and dietary restriction each extend lifespan in many animals. Because the degree of dietary restriction needed for longevity usually reduces fecundity, it is thought that both manipulations act via the same mechanisms. Ovariectomy extended lifespan and reduced feeding ~35%, and sham-operated females restricted to eat the same quantity as ovariectomized females daily also have extended lifespan. We addressed metabolic mechanisms associated with extended longevity. Treatments were: 1) sham-operated & full diet, 2) ovariectomized & full diet, 3) sham-operated & dietary restricted (fed the same amount consumed by group #2), and 4) ovariectomized & dietary restricted (fed 70% of that consumed by group #2). Consumption of O2 and release of CO2 was measured 1 hr before feeding, 1 hr after feeding, 5 hr after feeding, and 8 hr after feeding. Respiratory Exchange Ratios (RER) of sham-operated & full diet (n=3, overall mean = 0.65), ovariectomized & full diet (n=3, mean = 0.69), and ovariectomized & dietary restricted (n=4, mean = 0.74) groups were low at all four time points, suggesting predominantly lipid metabolism. In contrast, the sham-operated & dietary restricted group (n=3, overall mean = 1.00) had a high RER throughout, and especially after feeding, suggesting predominantly carbohydrate metabolism. Two-way repeated measures ANOVA revealed a significant effect of diet at 1 hr (P=0.01) and 8 hr (P=0.02) post-feeding, and marginal effects of surgery (P=0.09, P=0.07) and the interaction of diet and surgery (P=0.08, P=0.055) at those same times. The data suggest these grasshoppers typically burn lipids, but that intact grasshoppers on life-extending dietary restriction burn carbohydrates, while ovariectomized grasshoppers on the same daily feeding burn lipids.
