Multivitamin Attenuation of Reproductive Hormone Suppression by Azadirachta Indica (Neem) Leaf Extract in Female Rattus norvegicus Rats

Résumé

Neem (Azadirachta indica) is a widely used medicinal plant known for its therapeutic value, particularly in areas with limited access to modern healthcare. However, studies indicate that neem may affect fertility by altering reproductive hormones. Its antifertility effects are mainly linked to compounds such as azadirachtin, nimbin, nimbidin, and nimbosterol, which can disrupt the hypothalamic–pituitary–gonadal axis and influence hormones like FSH, LH, and Oestrogen. Although these effects are documented, the role of multivitamin supplementation in moderating neem-induced hormonal changes remains unclear and requires further study. This study investigated the dose-dependent impact of neem leaf extract on reproductive hormones in female albino rats and assessed whether multivitamins could mitigate these effects. Mature neem leaves were collected from CITAM Kisumu and the University of Eldoret. Forty female albino rats sourced from Maseno University were acclimated for one month under controlled conditions (22–25°C, 12-hour light/dark cycle). Twenty-four healthy, sexually mature rats were randomly assigned to eight treatment groups. Ethanol-extracted neem preparations were administered orally, with or without multivitamins, for 28 days. Post-treatment, blood samples were analyzed for follicle-stimulating hormone (FSH), luteinizing hormone (LH), and Oestrogen using ELISA at Moi Teaching and Referral Hospital. Data were analyzed using one-way ANOVA, Tukey’s post hoc test, and regression analysis, with significance set at p<0.05. Results showed dose-dependent suppression of reproductive hormones by neem. FSH decreased from 8.27±0.35 ng/mL in controls to 3.27±0.21 ng/mL in the highest neem dose (100 mg/kg), similar to the contraceptive group (3.03±0.15 ng/mL). LH declined from 6.17±0.35 ng/mL in controls to 2.90±0.20 ng/mL (Neem100), versus 2.57±0.21 ng/mL in the contraceptive group. Oestrogen levels fell from 52.59±2.55 pg/mL in controls to 13.53±1.25 pg/mL in Neem100, while controls and contraceptives had comparable levels (50.97±1.36 pg/mL). Multivitamin supplementation partially reversed these suppressive effects, increasing FSH to 5.87±0.15 ng/mL, LH to 5.13±0.15 ng/mL, and Oestrogen to 54.33±1.17 pg/mL in the Neem100+MV group. One-way ANOVA revealed highly significant differences among treatment groups for FSH (F 0.05(4,10) =181.67, p<0.0001), LH (F0.05(4,10) =88.24, p<0.0001), and Oestrogen (F0.05(4,10) =306.53, p<0.0001). Correlation analysis showed a very strong positive correlation between FSH and LH (r=0.992, p<0.0001), while Oestrogen exhibited weak, non-significant correlations with FSH and LH. In conclusion, neem leaf extract exerts potent contraceptive effects through dose-dependent suppression of key reproductive hormones, while multivitamin supplementation partially counteracts these effects. These findings emphasize the need for cautious use of neem-based products among women of reproductive age and highlight the importance of understanding interactions between herbal remedies and nutritional supplements. Further research is warranted to clarify the underlying mechanisms and long-term implications of such interactions.