1. IMPACT OF INHALATION EXPOSURE TO GASOLINE FUME ON THE MALE GONAD OF ALBINO RAT
Owagboriaye, F.O.1*, Dedeke, G.A.2, Bamidele, J.A.2, Olooto, E3. and Babawale, M.D1.
1-Department of Plant Science and Applied Zoology, Faculty of Science, Olabisi Onabanjo University Ago- Iwoye, Ogun State Nigeria.
2-Department of Biological Science, College of Natural Sciences, Federal University of Agriculture, Abeokuta Ogun State, Nigeria.
3-Department of Chemical Pathology and Immunology, Faculty of Basic Medical Sciences, Olabisi Onabanjo University, Ago-Iwoye, Ogun State Nigeria.
INTRODUCTION
Table 2: Relationship between the values of reproductive hormones in the rats subjected to varying hours of gasoline fume for 12 weeks
r – values
Testosterone
ABP
FSH LH
Prolactin 1
-.969**
-.892**
.847**
-.986**
.964**
.932**
-.880**
.854**
.943**
.893**
In Nigeria, gasoline is one of the fractionated products of crude oil. It contains very complex and inflammable components which have been reported to be xenobiotics, Endocrine Disrupting Chemicals (EDC) and volatile if left exposed and its fume constituting chemical pollutants in the environment (Zahlsen and Tri-Tugaswati, 1993).
The use of gasoline in industries and homes in Nigeria has rapidly increased in the recent times and in the course of usage, individuals are frequently exposed to pollutants from the gasoline fume.
Adverse effects of gasoline exposure has been reported (Uboh et al., 2010; Uboh et al., 2008) but evidence of its toxicological effect on male gonad is rare.
However, the present study was therefore designed to investigate the effect of gasoline fume exposure on the reproductive activities of male albino rats.
**Correlation (Pearson) significant at P < 0.001
Table 3: Level of oxidative parameters in the testis tissue of control and rats exposed to gasoline fume
METHODOLOGY
Experimental Animal and exposure to gasoline fume
Forty adult male albino rats (200 to 250g) were randomly assigned to five experimental treatments (T) with eight rats per treatment (T1, T2, T3, T4 and T5). They were exposed to varying daily hourly rates of exposure of 1(T2), 3 (T3), 5 (T4) and 9 hours (T5) of fumes from 500 mL of gasoline inside exposure chambers for 12 weeks. The control treatment (T1) was housed in a gasoline fume free section of the animal house.
Samples Collection and Assay
Blood samples were collected from the rats in baseline conditions between 8:00 A.M. and 10:00 A.M into a plain sample tubes.
The serum was centrifuged at 2500rpm for 10 min and the obtained sera samples were analyzed to determine the concentration of Liutenizing Hormone (LH), testosterone, Folicle Stimulating Hormone (FSH), prolactin and androgen binding protein (ABP) using Enzyme-Linked mmunosorbent Assay (ELISA) kits as described by the manufacturer.
The rat testes were dissected out and washed with saline solution. This tissue was minced and separately homogenized (10% w/v) using a homogenizer in ice-cold sodium potassium phosphate buffer (0.01 M, pH 7.4) containing 1.15% of KCl.
The homogenate was centrifuged at 10,000 xg for 20 min at 4oC and the supernatant was used to assay for oxidative enzyme activities (Heba and Mohamed, 2014).
Epididymis of the rats was dissected out into 10 mL of 0.87% warmed normal saline and sperm cells were counted using hemocytometer and motility was estimated with microscope
The lipid peroxidation end product, malondialdehyde (MDA), was measured as thiobarbituric acid reactive substance (TBARS) as described by Okhawa et al. (1979).
Reduced glutathione (GSH) assay was according to Hassan and Barakat (2008). The activities of antioxidant enzymes; catalase enzyme (CAT, EC ), superoxide dismutase (SOD, EC ) and glutathione peroxidase (GPx; EC ) were assayed using commercial assay kits according to the manufacturer’s instructions.
Data analysis
All Data were analysed using Statistical Package for Social Sciences (SPSS) version Post hoc test was done using the Student-Newman-Keuls (SNK). P < 0.05 was considered to be statistically significant.
SOD
(U/mg protein)
GSH
(U/g tissue)
CAT
GPx
MDA
(nmol/g tissue) T1
4.80±0.03a
9.47±0.11a
9.47±0.42a
15.81±0.10a
25.00±0.08e T2
4.04±0.05b
8.70±0.29b
8.36±0.31b
13.91±0.37b
26.98±0.11d T3
3.10±0.06c
6.93±0.15c
6.58±0.32c
10.51±0.37c
32.65±0.39c T4
2.00±0.06d
5.76±0.03d
5.87±0.13c
9.03±0.21d
39.16±0.59b T5
1.32±0.11e
4.47±0.32e
4.78±0.28d
7.66±0.27e
45.89±0.46a
abcdeMean (± Standard error) with same superscript in the same column are not significantly different (P > 0.05)
Figure 1: Sperm assessment of control and rats exposed to gasoline fume; Mean ±Standard error (error bar) for sperm motility and sperm count respectively with similar alphabet are not significantly different (P > 0.05); T1 = Control; T2 = 1 hour; T3 = 3 hours; T4 = 5 hours and T5 = 9 hours daily exposures to gasoline fume
OBSERVATIONS
Table 4: Pearson correlation coefficient between oxidative enzymes activities in testis tissues, reproductive hormones and sperm properties
Testosteron level was significantly higher in T1 than those exposed to the varying daily hours of gasoline fume. However, values of LH, FSH, ABP and Prolactin concentrations in the exposed rats significantly increased with increasing daily hours to gasoline fume exposure (Table 1).
Strong significantly negative (P < 0.001) Pearson Correlation existed between testosterone and LH, FSH, ABP and Prolactin. But, correlation between these hormones were positive and significantly strong (Table 2)
SOD, GSH, CAT and GPx significantly reduced (P < 0.05) in the testis of rats with increasing daily hours of gasoline fume exposure, however, level of MDA follows opposite trend (Table 3).
Values of percentage sperm motility and sperm count significantly reduced with increasing daily hour of gasoline fume exposure (Figure 1).
Strong correlation existed among the reproductive hormones, oxidative enzymes and sperm properties tested (Table 4)
Oxidative enzymes 
Reproductive hormones
Sperm
Testosteron
ABP
FSH LH
Prolactin
Motility
Count
Testis SOD
0.954**
-0.930**
-0.974**
-0.973**
-0.938**
0.988**
0.984**
Testis GSH
0.925**
-0.902**
-0.972**
-0.950**
-0.958**
0.980**
0.977**
Testis CAT
0.923**
-0.916**
-0.927**
-0.934**
-0.959**
0.935**
0.929**
Testis GPx
0.933**
-0.940**
-0.939**
-0.942**
0.949**
0.947**
Testis MDA
-0.920**
0.862**
0.938**
0.946**
-0.995**
-0.997**
**Correlation (Pearson) significant at P < 0.01
There are xenobiotic and Endocrine disrupting chemical (EDC) compositions in gasoline fume capable of inflicting adverse effect on male reproductive gonad of the exposed rats by generating free radicals and reactive oxygen species (ROS) from interactions of the gasoline components with the testicular cells of the rats. Male reproductive system development and function are susceptible to the effects of EDC (Jure, 2013). Thus, testis may be potential targets in animal and human populations exposed to gasoline fume. This assumes significance as humans constantly get exposed to gasoline fume and may suffer adverse health effects. However, further studies on the mechanisms of action and detailed examination of the cytoarchitecture of the dysfunctional testis is worth investigating. Meanwhile, direct exposure to gasoline by the populace should be discouraged.
Table 1: Concentrations of reproductive hormones in rats exposed to varying hours of gasoline fume for 12 weeks
Treatment
Testosterone
(ng/ml)
ABP
(mIu/ml)
FSH LH
Prolactin
T1(Control)
2.80±0.02a
28.25±0.44e
18.78±0.27d
18.96±0.10e
5.82±0.24c T2
1.99±0.01b
39.16±0.10d
19.16±0.16d
22.65±0.26d
6.15±0.11c T3
1.90±0.02c
42.58±0.33c
22.76±0.34c
23.71±0.32c
7.90±0.14b T4
1.51±0.01d
46.65±0.29b
27.56±0.42b
26.60±0.36b
8.04±0.14b T5
1.12±0.01e
47.86±0.16a
30.44±0.37a
28.11±0.10a
9.55±0.26a
REFERENCES
Jure, K. (2013). Reproductive Biomedicine Online, 26:
Hassan, A.M. and Barakat, A.H. (2008). Journal of Genetic Engineering and Biotechnology, 6(2); 29-38
Heba, M.A. and Mohamed, A.H. (2014). BioMed Research International 20; p 11
Okhawa, H. et al. (1979). Anal. Biochem. 95:
Uboh, F.E. et al. (2008). J. Pharmacol. Toxicol. 3:
Uboh, F. E., et al. (2010). Journal of Medicine and Medical Sciences; 1:
Zahlsen, I. and Tri-Tugaswati, A. (1993). Environmental Research, 63:
abcdMean values (±Standard error of mean) of each of the hormones in the same column having the same superscript are not significantly different at p < 0.05
The 5th International Conference of The West African Society of Toxicology: Developing Countries and Chemical Exposures: Upholding the Precautionary Principles, Benin City, Nigeria, 9 - 12 February, 2016.