Age-related differential expression of neuropeptide mRNAs in Aplysia

The basis of aging in the Aplysia nervous system is unknown. We now report age-related changes in mRNA expression of phe-met-arg-phe-NH2 (FMRFamide) and egg-laying hormone (ELH) in the abdominal ganglion, a part of the CNS, in young, mature and old Aplysia. Northern blot analysis revealed two mRNA species of 1.4 and 3.2 kb for RMRFamide and a single mRNA species of 0.8 kb for ELH. FMRFamide mRNA level increased 1.5-fold from young to mature and then decreased 3-fold in old animals. ELH mRNA gradually increased between young and mature animals and then escalated 25-fold in old animals. Age differentially affected the mRNA of these two peptides, which may contribute to behavioral changes previously reported.