Rat amylin, unlike human amylin, does not form fibrils. Thus toxic effects have not been reported for rat amylin while toxic effects have been reported for human amylin. Leffert, JD et al., Proc. Natl. Acad. Sci. USA, 86, 3127 (1989); Golpon, HA et al., Peptides, 24, 1157 (2003); Green, J et al, J. Mol. Biol. 326, 1147 (2003).