Desensitization of testicular ornithine decarboxylase to prostaglandin E2

Intratesticular injection of prostaglandin E2 at a dose of 10 or 25 micrograms per testis caused desensitization of the testis to ornithine decarboxylase activity at 24 h after the injection. PGE2 caused desensitization in both Leydig cells and seminiferous tubules. The desensitized testis was refractory to follicle stimulating hormone, luteinizing hormone and cAMP in addition to PGE2. These results indicate that testicular desensitization to PGE2 is at a step beyond cAMP formation.