Identification of prostaglandin D2 as a major prostaglandin in homogenates of rat brain

Prostaglandin (PG) E₂, D₂, F_2α and thromboxane B₂ (TxB₂) were determined in homogenates of rat brain by gas-chromatography - mass spectrometry. The level of PGD₂ was 735 ± 19 ng/g, of PGF_2α 150 ± 13 ng/g, of TxB₂ 112 ng/g and of PGE₂ 86 ± 8 ng/g. The same relative proportions of cyclo-oxygenase products were found in incubates of unstimulated sliced rat brain. ¹⁴C-PGH₂ was converted in high yield into PGD₂ by enzyme(s)_present in the soluble fraction of the homogenate. These results indicate that PGD₂ is the major cyclooxygenase product in the central nervous system of the rat.