Reproductive Effects of Medicinal Plant (Azadirachta indica) Used as Forage and for Ethnoveterinary Practices: New Insights from Animal Models

In some African and Asian countries, Azadirachta indica (AI) has been fed to livestock for decades and traditionally used to treat certain animal and human diseases. Recently, there are suspicions that the plant may possess anti-reproductive properties and concerns that the continued use of AI as forage or for folkloric medicine may detrimentally affect reproduction in the subjects. To address these challenges, this work determined the reproductive and fertility effects of a methanolic seed extract of AI (MSEAI) using adult female albino rats (AFARs) as an experimental model. Sixty-four AFARs were randomly assigned into four groups (A–D) of sixteen rats each. Group A was the control while groups B, C and D were treated daily with 50, 100 and 200 mg/kg of MSEAI respectively, for 28 consecutive days via oral gavage. Blood samples were collected for hormonal and biochemistry assays. Ovarian samples from the experimental rats were harvested for histopathological studies. Thereafter, the remaining experimental rats were bred, and certain fertility indices determined. The mean serum FSH and LH levels were significantly decreased (p ≤ 0.05) in the 100 and 200 mg/kg groups. The histopathological studies revealed massive follicular degeneration in the 100 and 200 mg/kg treatment groups. The fertility indices indicated that the post-implantation survival index was 100% in the control and 0% in the 200 mg/kg treatment group. No abortion occurred in the control and 50 mg/kg groups, but 25% and 100% of the pregnant does aborted in the 100 and 200 mg/kg treatment groups, respectively. Considering that high doses (100 mg/kg and 200 mg/kg) of MSEAI had significant anti-reproductive and antifertility properties, the use of AI as forage or for ethnoveterinary medicine in breeding females may adversely affect their reproductive potentials. However, the anti-reproductive and antifertility effects could be utilized in rodent depopulation programs in animal agriculture and as a contraceptive to limit the proliferation of stray dogs, known to be reservoirs of the rabies virus in developing countries. Moreover, the MSEAI could be further refined for human use as an effective, cheap, eco-friendly and acceptable alternative to synthetic/modern contraceptives, the use of which is limited in developing nations due to superstitious beliefs and their multiple side effects.