Consistent with the importance of CAT-1/VMAT for 5-HT intracellular storage and 5-HT release (Duerr et al., 1999), 5-HT was dramatically reduced or absent in NSM, ADF, and HSN as well as in AIM and RIH in two
cat-1 alleles. Thus, 5-HT accumulation in AIM and RIH is also influenced by CAT-1/VMAT activity.