Effects of botulinum toxin A on the contractile function of dog prostate.
OBJECTIVE
To study effects of botulinum toxin A (BoNT/A) on prostate contractile function in dogs.


METHODS
One hundred units (N=6) or 200 units (N=5) BoNT/A was injected into dog prostate. Sham control group (N=7) received normal saline injections. Before and 1 mo after injection, prostate urethral pressure response to electrostimulation and intravenous (IV) norepinephrine was measured. Contractile responses of prostate strips were tested in tissue bath. Structural changes were evaluated with conventional histology and smoothelin immunohistochemistry.


RESULTS
Injection of normal saline and 100 units BoNT/A did not significantly change prostate urethral pressure response to IV norepinephrine and electrostimulation. However, injection of 200 units BoNT/A significantly reduced prostate urethral pressure response to IV norepinephrine and electrostimulation. Contractile responses of prostate strips to potassium chloride, electrostimulation, and phenylephrine did not differ between sham control and 100U groups. In the 200U group, however, all responses were less than those of sham controls. Control and BoNT/A groups exhibited nitric oxide-related relaxation in prostate strips precontracted by phenylephrine. Injection of 100 units BoNT/A induced mild atrophy of prostate gland; injection of 200 units BoNT/A induced more pronounced atrophic changes in prostate gland and vacuoles formation in smooth muscle cells of stromal tissue.


CONCLUSIONS
Injecting BoNT/A into dog prostate reduces contractile function while maintaining relaxation response of the prostate. These effects make BoNT/A a viable option in managing prostate-related symptoms. However, large, randomized clinical studies to determine long-term effects and safety of BoNT/A application in human prostates are required.
Lin
Alex Tong Long
AT
Division of Urology, Department of Surgery and Pathology, Taipei Veterans General Hospital, Taipei, Taiwan. lintl@vghtpe.gov.tw
Yang
An Hang
AH
Chen
Kuang-Kuo
KK
D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation; D008297:Male; D009465:Neuromuscular Agents / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D011467:Prostate / Q000187:drug effects*; D013718:Tensile Strength
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A; D009638:Norepinephrine