OBJECTIVETo investigate the protective effect of ERbeta on the penile vascular endothelium in mice.

METHODSWe randomly selected 12 ERbeta knockout (ERbetaKO) and 12 C57BL/6 male mice, and divided them into four groups: normal control, ERbetaKO, ERbetaKO + TNFalpha, and wild-type + TNFalpha group. The former two were treated with normal saline, while the latter two by intraperitoneal injection of TNFalpha at 6 microg/(kg x d) for 14 days. Then we observed the spontaneous erectile response induced by APO and changes of the endothelial cells by immunohistochemical staining of CD34 and vWF, and detected cell apoptosis in the penile cavernous tissue by TUNEL.

RESULTSCompared with the normal control group, the ERbetaKO group showed significantly increased erectile latency (P<0.05), but no significant difference in the number of erections; the ERbetaKO + TNFalpha and wild-type + TNFalpha groups, too, exhibited remarkably longer erectile latency (P<0.05) but fewer erections (P<0.05), with even more obvious changes in the ERbetaKO + TNFalpha group. The expressions of CD34 and vWF were significantly reduced in the ERbetaKO group (2.25 +/- 0.50 and 2.00 +/- 0.00), ERbetaKO + TNFalpha group (0.25 +/- 0.50 and 0.33 +/- 0.58) and wild-type + TNFalpha group (1.50 +/- 0.58 and 1.25 +/- 0.50) as compared with those in the control (3.00 +/- 0.00 and 2.75 +/- 0.50) (P<0.05), even lower in the ERbetaKO + TNFalpha than in the wild-type + TNFalpha group (P<0.05). Apoptotic cells were found only in the ERbetaKO + TNFalpha group.

CONCLUSIONAfter ERbeta knockout and especially after treated with the endothelial injury factor TNFalpha, endothelial cells are decreased in the penile vessels in mice, which suggests that ERbeta has a protective effect on the penile cavernous sinus endothelium.