*2.6. Statistical Analysis*

We analyzed the expression levels NUCB2 mRNA in the whole brain and stomach of 22 animals in total at 5 wph (*n* = 12) and 27 wph (*n* = 10). Expression levels were analyzed by the ΔΔCt method and normalized to the housekeeping gene TATA box binding protein (TBP) (Table S2). Fold changes represent the normalized fold difference in expression levels relative to 5 weeks-old brain. T-test and *p*-value were calculated with Graphpad Prism among young and old brains and young and old rostral intestinal bulbs. Furthermore, T-test and p-value were also calculated for young brains versus young intestinal bulbs and old brains versus old intestinal bulbs.
