Antifertility effects of Azadirachta indica methanol seed extract on canine spermatozoa in vitro

Objective: To investigate the effects of Azadirachta (A.) indica methanol seed extract on canine male fertility in vitro. Methods: The effect of the A. indica methanol seed extract (2.5, 5.0, 10.0 and 20.0 mg/mL, respectively) on canine spermatozoa was evaluated in vitro at 1.0, 2.5, 5.0 and 10.0 min post-treatment. The two controls were comprised of sperm sample in phosphate- buffered saline, and sperm sample in phosphate-buffered saline and 1% dimethyl sulfoxide, respectively. The experiment was repeated (n=3) in duplicates with semen collected from 3 adult Basenjis. The effect of A. indica methanol seed extract treatments on canine spermatozoal total and progressive motility (phase-contrast microscopy), sperm vitality (eosin-nigrosin vital staining method) and total abnormalities (phase contrast microscopy, eosin-nigrosin staining and Papanicolaou staining methods) were determined. Results: A. indica methanol seed extract treatment caused a concentration and time-dependent decrease in sperm percentage total motility, progressive motility and vitality. The absence of sperm revival post-treatment provided evidence of a permanent or irreversible incapacitation of sperm by A. indica methanol seed extract. Conclusions: The inhibition of sperm motility and significant spermicidal effect observed post-treatment suggest that A. indica methanol seed extract may produce a potent antifertility or contraceptive effect in dogs if applied as an intra-vaginal cream pre- coitus.