Investigation of the Pharmacological Effects of Moringa Oleifera Aqueous Extract on Oxidative Damages and Reproductive Performances Induced by Heat Stress in Female Rabbit

Abstract

Heat stress is considered as one of the factors altering animal productivity and reproductive performances by impairing animal physiology due to the imbalance between heat accumulation and heat loss. Moringa oleifera (MO) is one of the best antioxidant plants because of its numerous bioactive compounds. It is reported to alleviate damages caused by oxidative stress and improve animal productivity and reproductive performances. The general objective of this study was to investigate the pharmacology of MO extract in the management of heat stress disturbances on reproductive performances and oxidative stress in rabbit does. Fresh MO leaves, seeds and barks were collected from 2 to 3 years old MO trees of Bukavu city of South Kivu province in Democratic Republic of Congo and Masii village of Machackos County in Kenya and 300 g of each dried powder was mixed with 700 ml of distilled water. Qualitative and quantitative assessment of bioactive compounds including flavonoids, tannins, alkaloids, phenols, glycosides, saponins and terpenoids were performed following standard methods while the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to evaluate the antioxidant activity. Thereafter, twenty-eight rabbit does were randomly distributed to 4 treatments groups (with 7 animals per group) and assigned for 80 days to different room temperatures, relative humidity, temperature humidity index (THI) and of Moringa oleifera aqueous seed extract (MOASE) as follows: group 1 (T0): ambient temperature (18–24°C), 59 ±0.48%, 23.6 ±1.52; group 2 (T1): 35–36°C, 64 ±0.6%, 32.5 ±0.7, 100 mg of MOASE; group 3 (T2): 35–36°C, 64 ±0.6%, 32.5 ±0.7, 200 mg of MOASE; group 4 (T3): 35–36°C, 64 ±0.6%, 32.5 ±0.7. In each rabbit cage, electrical heaters were used from 08:00 h to 16:00 h following with the exposition to the room air temperature as in the control group. The selected range of temperature, relative humidity and THI were chosen according to results observed in the pilot study. During the experiment period, food consumption, body weight and body weight gain as well as rectal and skin temperature were measured daily. Reproductive functions including mating method, number of services per conception, self’fur removal, gestation length, litter size, kit body weight, the weight of the litter, milk intake and milk efficiency were recorded or calculated. All animals were sacrificed after 80 days and data referring to blood parameters, oxidative stress biomarkers, weight of organs, hormones, kidney and ovary histology were collected. Results indicate the presence of glycosides in all the plant parts but the absence of terpenoids in seeds from DRC, phenols and flavonoids in barks from both countries. The highest extraction yield was in leaves of MO from DR Congo and seeds from Kenya. The DPPH showed that MO leaf and seed extracts have appreciable and concentration-dependent increase in scavenging effect. A significant decrease (P<0.05) was observed in the skin and rectal temperatures, weight of lung, liver, kidney, hematological parameters such as mean cell volume, white blood cells, lymphocytes, biochemical parameters such as creatinine, urea, alanine aminotransferase, aspartate amino-transferase as well as oxidative stress biomarkers like kidney lipid peroxidation in rabbits from T1 and T2 compared to those of T3. However, a significant increase (P<0.05) in ovary weight, hemoglobin, red blood cells, glucose, total protein as well as kidney protein, catalase, superoxidase dismutase, reduced glutathione and lipid peroxidation was observed in animals of T1 and T2 compared to those of T3. Regarding reproductive parameters, a significative increase (P<0.05) body weight and body weight gain of both pregnant and lactating female rabbit’s, fur removal and litter weight, litter size, kit body weight and kit weight gain, weekly milk production and daily milk efficiency and estradiol, luteinizing hormone, follicular stimulating hormone and cortisol contents in rabbits from T1 and T2 compared to those of T3. A significant decrease (P<0.05) in the number of services per conception, milk intake and progesterone content in animals of T1 and T2 compared to those of T3 was noted. Kidney histology of animals of T1 and T3 indicated cortical renal parenchyma with fibroblast proliferation in the interstitial tissues and a tubular epithelial cell swelling while ovary tissue of T1, T2 and T3 animals showed structural alterations. It was concluded that Moringa oleifera seeds possess antioxidant activities which could be attributed to some phytochemical components observed in Moringa. These bioactive compounds, when Moringa oleifera aqueous seed extract is administrated at 200mg/kg b.w., minimize the adverse effects of heat stress inducing physiological and reproductive impairment in female rabbits. Other parts of Moringa oleifera (pods, stembark) on heat stress disturbances in rabbits should be studied using organic solvents while the potential toxicity of Moringa oleifera aqueous seed extract should be checked.