RAT PROSTAGLANDIN D-2 SYNTHETASE - ITS TISSUE DISTRIBUTION, CHANGES DURING MATURATION, AND REGULATION IN THE TESTIS AND EPIDIDYMIS

The changes in glutathione-independent prostaglandin D-2 synthetase (P GD-S) during maturation in the rat were determined in selected organs by an RIA using PGD-S purified from rat cerebrospinal fluid and a mono specific anti-rat PGD-S polyclonal antibody. In a survey of its tissue distribution in various organ extracts and biological fluids, it was found that the concentration of PGD-S was highest in the epididymis-ab out 6- and 80-fold greater than that in the brain and testis, respecti vely. During maturation, PGD-S concentration increased steadily in the testis and epididymis; this is in contrast to the pattern of changes in the brain and liver, which showed a general trend of decline. Rever se transcription-polymerase chain reaction and Southern blotting were used to demonstrate the presence of PGD-S mRNA transcript in the testi s and in Sertoli and germ cells. In the epididymis, the steady-state P GD-S mRNA level was highest in the caput, followed by the cauda and co rpus. Orchiectomy induced a drastic reduction of PGD-S concentration i n all three epididymal compartments. Administration of dihydrotestoste rone (DHT) failed to restore the reduced epididymal PGD-S level except in the caput epididymis, where 4 days after DHT treatment the level o f PGD-S was restored to about 50% of the pre-orchiectomized level; thi s suggests that the epididymal PGD-S level is not entirely regulated b y androgen and that another yet to be identified testicular factor(s) is likely to be involved in its regulation. Germ cell-conditioned medi um was also shown to stimulate PGD-S expression in the Sertoli cell. T hese results illustrate that PGD-S is an important molecule in testicu lar and epididymal function and that it is likely involved in spermato genesis and sperm maturation.