Soa genotype selectively affects mouse gustatory neural responses to sucrose octaacetate

In mice, behavioral acceptance of the bitter compound sucrose octaacetate ( SOA) depends on allelic variation of a single gene, Soa. The SW. B6-Soa(b) congenic mouse strain has the genetic background of an "SOA taster" SWR/J s train and an Soa-containing donor chromosome fragment from an "SOA nontaste r" C57BL/6J strain. Using microsatellite markers polymorphic between the tw o parental strains, we determined that the donor fragment spans 5-10 cM of distal chromosome 6. The SWR/J mice avoided SOA in two-bottle tests with wa ter and had strong responses to SOA in two gustatory nerves, the chorda tym pani (CT) and glossopharyngeal (GL). In contrast, the SW. B6-Soa(b) mice we re indifferent to SOA in two-bottle tests and had very weak responses to SO A in both of these nerves. The SWR/J and SW. B6-Soa(b) mice did not differ in responses of either nerve to sucrose, NaCl, HCl, or the bitter-tasting s timuli quinine, denatonium, strychnine, 6-n-propylthiouracil, phenylthiocar bamide, and MgSO4. Thus the effect of the Soa genotype on SOA avoidance is mediated by peripheral taste responsiveness to SOA, involving taste recepto r cells innervated by both the CT and GL nerves.