Meeting Abstract
P3.170 Friday, Jan. 6 Life-extending ovariectomization or dietary restriction each show a lack of cellular responses, despite large differences in storage levels, in grasshoppers KELLENBERGER, JW*; VIRAY, EN; SMITH, AL; HAHN, DA; HATLE, JD; Univ. of North Florida; Univ. of North Florida; Univ. of North Florida; Univ. of Florida; Univ. of North Florida jhatle@unf.edu
Reduced reproduction or reduced diet extends lifespan in many animals. Because life-extending dietary restriction (DR) decreases fecundity, it has been suggested that reduced reproduction and reduced diet may extend lifespan by similar mechanisms. In the grasshopper Romalea microptera, ovariectomy (OVX) increased lifespan 16% and reduced feeding 36%. Dietary restriction (a 30% reduction in feeding) increased lifespan 17% and reduced fecundity 15%. These similarities led us to compare the physiology of OVX grasshoppers with DR grasshoppers that were fed the same amount as that consumed by the OVX group. Ovariectomy increased fat body mass 3-fold and increased collected hemolymph 5-fold (both P<0.0001), a massive increase in storage tissue. Historically, the free-radical theory of aging has suggested that increased anti-oxidant activity may help increase lifespan. However, no significant differences were recorded in total anti-oxidant activity for mandibular muscle (P=0.62) or hemolymph (P=0.12) due to OVX or DR. A more recent hypothesis of aging suggests that increased mitochondrial count decreases mitochondrial workload, leading to lifespan extension. Estimates of mitochondrial counts in fat body tissues showed no effects of OVX or DR (P=0.27). TOR signaling, a nutrient-dependent sister pathway to insulin-like signaling, has also been implicated in mediating lifespan by DR. No effect of DR or OVX was observed on TOR transcript quantity in femur muscle (P=0.23). Thus far, life extension by OVX and DR appear to work through massively different levels of organismal storage but similar cellular responses. We thank NIH for awarding 1R15AG028512-01 and 2R15AG028512-02A1 to JH.
