Stinging Nettle Leaf Extract Affects Smooth Muscle Contractility in the Isolated Rat Prostate Gland by Acting within the Purinergic System

Hypothesis / aims of study Urtica dioica (commonly known as stinging nettle) is used worldwide as an alternative to conventional pharmacotherapies for benign prostatic hyperplasia (BPH). The root extract is commonly used in Europe, primarily in Germany, for the treatment of the symptoms associated with BPH. It is thought to alleviate lower urinary tract symptoms (LUTS) by reducing stromal proliferation and thereby decreasing the size of the prostate gland [1]. The leaf extract has been used in traditional medicine in Turkey for the relief of lower urinary tract symptoms [2], as well as in Morocco for the treatment of hypertension [3]. This hypertensive action is via a vasorelaxant mechanism which infers a relaxant effect on smooth muscle. As stinging nettle appears to be effective in treating LUTS associated with BPH and drugs which relax prostatic smooth muscle are known to be the most effective for this, it is hypothesised that commercially available stinging nettle extracts affect the prostatic smooth muscle contractility. The objectives of this study were to investigate: (1) the smooth muscle relaxant efficacy of commercially available stinging nettle leaf and root extracts on the contractility of the rat prostate gland, (2) the pharmacological mechanism of action any smooth muscle relaxation and (3) to identify any bioactive components of these extracts.