Enhancement of the turtle olfactory responses to fatty acids by treatment of olfactory epithelium with phosphatidylserine.

The turtle olfactory epithelium was treated with suspensions of various lipids and their effects on the olfactory responses were examined by measuring the olfactory bulbar responses. The phosphatidylserine (PS)-treatment greatly lowered the threshold for n-valeric acid and enhanced its responses at all concentrations examined. The responses to isovaleric acid and n-butyric acid were also greatly enhanced by the PS-treatment. The responses to ten other odorants examined were a little enhanced or unchanged by the PS-treatment. The enhanced responses to the fatty acids returned to the original level about 10 h after the treatment. It was confirmed that PS was incorporated into olfactory epithelium by incubating the epithelium with PS-suspension containing [14C]PS. The treatment of the epithelium with phosphatidic acid or cardiolipin unchanged or suppressed the responses to odorants including the fatty acids. The present results suggest that lipids as well as proteins in the receptor membranes play an important role in odor reception.