Abstract:
Prolonged exposure to lead induces oxidative stress which is implicated in male infertility.
Tithonia diversifolia Leaf (TDL) has been reported in folkloric medicine to possess anti inflammatory properties. There is dearth of information on the effects of TDL on lead induced male reproductive dysfunctions. Therefore, the effects of Methanol Extract of TDL
(METDL) on Lead Acetate (PbA)-induced reproductive toxicity were investigated in male
Wistar rats.`
Tithonia diversifolia leaves were collected from Botanical Garden, University of Ibadan, and
identified at Forestry Research Institute of Nigeria, Ibadan (FHI No.: 110652). The leaves
were air-dried, pulverised, macerated in methanol, and the filtrate was concentrated using
rotary evaporator. Identification of the phytochemical constituents present in METDL was
done by Gas Chromatography Mass Spectrometry (GC-MS). Forty male Wistar rats (120-150
g) were assigned into eight groups (n=5) and treated thus: Group 1 (Distilled Water, 5
mL/kg), Group 2 (15 mg/kg PbA), Group 3 (50 mg/kg METDL), Group 4 (15 mg/kg PbA +
50 mg/kg METDL), Group 5 (100 mg/kg METDL), Group 6 (15 mg/kg PbA + 100 mg/kg
METDL), Group 7 (50 mg/kg phytol) and Group 8 (15 mg/kg PbA + 50 mg/kg phytol).
Twenty-four hours after the last administration, blood samples were collected via cardiac
puncture from the animals under anaesthesia (50 mg/kg sodium thiopental, i.p.). Serum
Gonadotropin-Releasing Hormone (GnRH), Follicle Stimulating Hormone (FSH), Luteinizing
Hormone (LH), testosterone, nitrotyrosine, Interleukin-1β (IL-1β) and Tumour Necrosis
Factor Alpha (TNF-α) were measured using ELISA technique. Testis and hypothalamus were
harvested for spectrophotometric analysis of Malondialdehyde (MDA), Superoxide Dismutase
(SOD), catalase and reduced glutathione. Histological analysis of parafine-embedded testis
and hypothalamus was done via Hemotoxylin and eosin staining technique. Semen analysis
was done using Computer Aided Sperm Analyser (CASA). Data were analysed using
Students‘ t-test and ANOVA at α0.05.
Phytol (3,7,11,15-tetrametylhexadec-2-en-1-ol) had the highest percentage (14.7%) of all the
compounds that have antioxidant properties identified in METDL. Sperm motility, livability
and counts were significantly increased in Groups 4 (78.8±1.8%; 66.0±3.3%; 383.2±2.1x106
cell/mL) and 8 (75.0±3.2%; 66.0±4.0%; 78.0±3.7 x106 cell/mL) compared to Group 2
(46.4±1.1%; 42.0±3.7%; 34.8±1.3 x106 cell/mL). Testicular SOD (31.2±1.5 vs. 17.3±0.9
Unit/mg tissue) and catalase (2.5±0.2 vs. 0.9±0.2 Unit/mg tissue) were significantly increased
in Group 4 compared to Group 2. Testicular and hypothalamic MDA were significantly
decreased in Group 8 (0.4±0.0 µM/mg protein; 0.2±0.0 µM/mg protein) compared to Group 2
(0.5±0.0 µM/mg protein; 0.5±0.0 µM/mg protein). Serum TNF-α, IL-1β and nitrotyrosine
levels were significantly decreased in Group 8 (63.0±2.0 pg/mL; 433.8±1.8 pg/mL; 3.5±0.2
ng/mL) compared to Group 2 (95.5±1.9 pg/mL; 683.8±2.3 pg/mL; 7.5±0.2 ng/mL).
Significant increase was observed in testosterone, LH, FSH and GnRH in Groups 4
(0.2±3.2x103 ng/mL; 4.2±1.2 mIU/mL; 0.7±0.1 mIU/mL; 1260.0±5.4 pg/mL) and 8
(0.1±3.5x103 ng/mL; 5.1±1.1 mIU/mL; 0.8±0.1 mIU/mL; 1319.0±3.6 pg/mL) compared to
Group 2 (0.1±3.8x103 ng/mL; 1.7±0.7 mIU/mL; 0.4±0.0 mIU/mL; 1056.0±3.9 pg/mL),
respectively. Histology of the testes and epididymides showed cyto-architectural distortion
only in Group 2.
iii
Tithonia diversifolia alleviated lead acetate-induced reproductive toxicity via the mitigation of
oxidative stress. The methanol extract also prevented inflammatory response to lead acetate
toxicity.
