Sedation produced by prostaglandins is not a nonspecific fatty acid effect.

The fatty acid specificity of the depressant actions associated with prostaglandin (PG) administration was studied in mice. Administration of PG-E2 (0.4 and 1.0 mg/kg) or PG-D2 (0.4 and 4 mg/kg) significantly potentiated pentobarbital sleeping time. Arachidonic acid (3.3 mg/kg) administration also significantly potentiated pentobarbital sleeping time. Pretreatment with indomethacin (3 mg/kg) or ibuprofen (10 mg/kg) inhibited the potentiation of pentobarbital sleeping time produced by arachidonic acid. A nonspecific fatty acid (11, 14, 17-eicosatrienoic acid), which cannot be incorporated into the PG synthetic scheme, did not potentiate pentobarbital sleeping time. These results imply that the depressant activity associated with PG administration is a specific PG-induced action rather than a general effect of long-chain unsaturated fatty acids.