RESUMO
<p><b>OBJECTIVE</b>To explore the expressions of HO-2 and CO in the corpus cavernosum of castrated rats in order to further study the pathogenesis of erectile dysfunction (ED).</p><p><b>METHODS</b>We randomly divided 72 male SD rats into four groups: normal control, sham operation, castration, and castration + ZnPP. We detected intracavernous pressure (ICP) and penile erection in the basic condition and after apomorphine (APO) induction, determined the expression of the HO-2 protein in the corpus cavernosum by laser scanning confocal microscopy, and measured the level of CO by spectrophotometry during different periods of penile erection.</p><p><b>RESULTS</b>The ICP in the basic condition and that after APO induction and the rate of penile erection were decreased significantly in the castration group ([11.68 ± 0.69] mmHg, [54.81 ± 3.86] mmHg, and 33.3%) and the castration + ZnPP group ([11.20 ± 0.71] mmHg, [41.17 ± 5.41] mmHg, and 22.2%) as compared with the normal control ([22.83 ± 2.66] mmHg, [66.92 ± 7.77] mm-Hg, and 100%) and the sham operation group ([23.35 ±2.22] mmHg, [70.43 ?7. 22] mmHg, and 100%) (all P <0. 01). After APO induction, ICP in the castration + ZnPP group was remarkably reduced in comparison with that in the castration group (P < 0.01), and so was the expression of the HO-2 protein before and during penile erection in the castration (445.4 ± 23.7 and 847.4 ± 35.0) and the castration + ZnPP group (390.1 ± 29.7 and 526.0 ± 52.5) compared with the normal control (512.7 ±57.4 and 1145.2 ± 89.8) and the sham operation group (583.7 ± 8.0 and 1016.3 ± 79.8), the expression of the HO-2 protein significantly decreased in the castration group (445.4 ± 23.7 and 847.4 ± 35.0) (P < 0.05 or 0.01), markedly lower in the castration + ZnPP than in the castration group during penile erection (P < 0.01) but with no significant differences among the four groups after it. Before, during and after penile erection, the levels of CO were remarkably decreased in the castration ([20.59 ± 1.01], [32.53 ± 1.26], and [18.71 ± 1.22] x 10(-7) nmol/L) and the castration +ZnPP group ([12.52 ± 1.05], [21.90 ± 1.02], and [16.56 ± 0.55] x 10(-7) nmol/L) as compared with the normal control ([26.76 ± 1.41], [48.25 ± 1.01], and [27.10 ± 1.58 ] x 10(-7) nmol/L) and the sham operation group ([25.41 ± 2.09], [ 47.90 ± 1.22], and [25.67 ± 1.20] x 10(-7) nmol/L) (P < 0.05 or 0.01), significantly lower in the castration + ZnPP than in the castration group during penile erection (P < 0.01).</p><p><b>CONCLUSION</b>Decreased expressions of HO-2 and CO may correlate with erectile dysfunction in castrated rats.</p>