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Keywords:

  • lithium;
  • erectile dysfunction;
  • corpus cavernosum;
  • endothelium;
  • cyclooxygenase;
  • indomethacin;
  • nitric oxide;
  • rats

OBJECTIVE

To verify the effect of chronic lithium administration on the endothelium-dependent relaxation of rat corpus cavernosum, as lithium is a major drug for treating bipolar disorder and some studies showed that lithium might cause erectile dysfunction in such patients, by a mechanism as yet unknown.

MATERIALS AND METHODS

LiCl (600 mg/L) was dissolved in drinking water and Sprague–Dawley rats received the solution for 30 days; control rats received tap water. After 30 days corporeal strips were prepared from both groups, mounted under tension in oxygenated organ baths, and pre-contracted with phenylephrine (7.5 µm). After equilibration, the strips were relaxed by acetylcholine (10 nm to 1 mm) in the presence or absence of indomethacin (a cyclooxygenase inhibitor; 20 µm). Furthermore, the relaxant responses to sodium nitroprusside (1 nm to 1 mm), a nitric oxide (NO) donor, were investigated in both groups. NADPH-diaphorase histochemistry was used to identify NO synthase within cavernosal tissue strips of both groups.

RESULTS

The acetylcholine-dependent relaxation was significantly lower in lithium-treated rats than in controls. Although indomethacin decreased significantly the relaxant responses to acetylcholine in controls, it increased the relaxant responses in lithium-treated rats. NADPH-diaphorase staining was greater in the chronic lithium-treated than in control preparations. Sodium nitroprusside produced similar relaxation in both groups.

CONCLUSION

Chronic lithium administration can impair the endothelium-dependent relaxation of rat corpus cavernosum; NO availability might decrease after lithium administration and the cyclooxygenase pathways might have a role in this effect.