Prostaglandin I-2, a possible thermo-sensory mediator in Paramecium

Thermo-sensory mechanisms are little understood. The protozoan, Paramecium multimicronucleatum, is sensitive and responsive to a cooling stimulus. We found that inhibitors of prostaglandin (PG) biosynthesis reduced the respon se to the cooling stimulus. Inversely, the response suppressed by the inhib itors was recovered by application of stable PGI(2) analogs, including ilop rost. Paranecium cells showed binding activity specific for [H-3]iloprost. Moreover, an arachidonic acid metabolite, possibly PGI(2), was rapidly incr eased in response to the cooling stimulus, suggesting that prostaglandin bi osynthesis plays a crucial role in the cooling-sensory transduction, Parame cium may be a useful model for the investigation of the molecular basis of thermo-sensory mechanisms. (C) 2000 Academic Press.