Figure 3. Age-dependent changes to myenteric plexus are associated with delayed intestinal transit.
Immunostaining of wholemount preparations of LMMP labeled with pan-neuronal marker HuC/D (red) and pSTAT3 (green) revealed increased numbers of Hu+ neurons expressing pSTAT3 (arrows) in old compared with young mice (A). This difference expressed as a percent of neurons (pSTAT3+Hu+/total Hu+) was statistically significant. Increased STAT3 activity corresponded to an increase in number of Hu+ neurons (red) co-expressing the apoptosis marker cleaved caspase-3 (Asp175, green, arrows) in old mice compared to young (B). As a percent of neurons (Asp175+Hu+/total Hu+) this difference was statistically significant. Old mice also demonstrated a statistically significant reduction in neuronal density (Hu+ cells/ganglia area (100 μm2)) compared to young (C). Whole intestinal transit studies performed on a separate cohort of young and old mice revealed prolonged transit times in old mice (D). **p<.01, ***p<.001 by t-test. Scale bars, 50 μm.
