To investigate the effects of prostaglandin E₂ (PGE₂) and its antireceptor antibody on prostatic blood flow regulation using a rat model. We estimated that PGE₂ participated in the signaling pathway of hormonal regulation of the prostatic blood flow.

The rats were castrated and injected locally with dihydrotestosterone (200 ng/head) or PGE₂ (250 ng/head) directly into the prostatic membrane. After local dihydrotestosterone or PGE₂ administration, anti-PGE₂ receptor antibody (200 ng/head) was injected locally to investigate interruption of the signaling pathway. After administration, we evaluated the relative prostatic blood flow using a laser blood flow meter. The change in cyclooxgenase-2 mRNA expression and the changes in PGE₂ concentration in response to androgen stimulation were also examined.

PGE₂ was involved in blood flow regulation with activity equal to that of androgen. The effect of dihydrotestosterone was abolished by coadministration with anti-PGE₂ receptor antibody. Cyclooxgenase-2 gene expression was upregulated in response to androgen stimulation. The PGE₂ concentration also increased in response to androgen stimulation.

Our finding of PGE₂ participation in androgen regulation of prostatic blood flow might lead to pathophysiologic elucidation of prostatic diseases.