Effects of purified newly developed botulinum neurotoxin type A in rat prostate.

Objectives: To investigate the efficacy of a newly purified neurotoxin (NTX) in male rat prostates. Several reports have suggested that intraprostatic injection of botulinum toxin type A has demonstrated efficacy against symptomatic benign prostatic hyperplasia. NTXs associate with nontoxic components and form large complexes designated "progenitor toxins." In general, progenitor toxins are used, because they are easily obtained and are more stable than NTXs. However, they have side effects for some patients in whom anti-progenitor toxins, including anti-NTX antibodies, are produced after several injections. We purified NTXs without their nontoxic components using a simple procedure.

Methods: Adult male Sprague-Dawley rats were injected with 5 U of NTX or saline into their prostates, which were harvested and weighed after 1 or 4 weeks. The effects of the NTX on the prostate were histologically and immunohistochemically studied using hematoxylin-eosin, synaptophysin, and terminal deoxynucleotidyl-mediated deoxyuridine triphosphate nick end labeling staining.

Results: In the NTX-treated rats, the prostate weight was reduced and atrophy and diffuse apoptosis were observed. Moreover, synaptophysin-positive cells in the epithelium were decreased after NTX injection.

Conclusions: Intraprostatic NTX injection induces prostate apoptosis and atrophic change in the rat prostate. These results suggest that NTX injection might be a promising material for treatment of patients with benign prostatic hyperplasia.