Background: The central nervous system is one of the most important systems affected by formaldehyde (FA). Aim of Work: This study was designed to assess its toxic neuropsychiatric effects both clinically and experimentally and the protective effects of garlic. Methods: Clinically: 20 workers in the gross anatomy laboratory and 20 libertarians underwent a standardized clinical assessment including medical, neurological and psychiatric examination. Experimental: 40 male rats were divided randomly into four groups. Group I is control group. Group II received 10 mg/kg of FA intraperitoneally once daily for 14 days. Group III was treated with fresh garlic juice (1 ml/100g body weight) once daily by oral gavage for 14 days. Groups VI received fresh garlic juice plus formaldehyde daily for 14 days. At the end of the experiment, the rats’ brains were obtained for histological examination and biochemical analysis. Results: Clinical and psychiatric profile of FA exposed persons’ revealed cognitive impaired, anxious and depressed persons. There were hostile persons with more hostility toward outside. Experimentally, hippocampal and frontal superoxide dismutase and reduced glutathione showed highly significant decrease while malondialdehyde and nitric oxide level showed highly significant increase in formaldehyde treated group when compared with control group. Also histopathological changes in the hippocampal and frontal cortices by light microscope revealed many distorted cells with deeply stained shrunked nuclei and cytoplasm was surrounded by vacuolated pale areas in FA exposed group. Minimization of biochemical and histopathological changes were observed in combined formaldehyde and garlic treated group. Conclusion: The profiles of personality arouse dangerous affairs about the toxic impact of FA on persons, family, and society. Formaldehyde-induced neuronal damage, oxidative stress and lipid peroxidation in brain were minimized by addition of garlic.
Formaldehyde (FA) is a ubiquitous chemical agent. It is a part of our general outdoor environment. Also, it is a part of our indoor working and residential environment. It is believed that whole civilized population is exposed to formaldehyde [
In addition, FA can be produced as burning product of wood, coal, tobacco, natural gas, and kerosene [
In the medical field, FA is often utilized in laboratories. Fixation and long-run storage of organs and cadavers are achieved by FA. Also, it's utilized in tissue fixation stage in microscopic anatomy and pathology laboratories. Additionally, it's usually utilized in dental coating materials, within the treatment of cases with persistent urinary tract infection and as a protecting agent for a few medicines. Moreover, dialysis solutions typically contain formalin [
Formaldehyde has a high propensity for reacting with RNA, DNA, and protein, which leads to many health hazard [
This study was designed to assess the toxic neuropsychiatric effects of FA clinically and experimentally and the protective effects of garlic (as an antioxidant) against the neurotoxicity-induced by FA in rats.
This study consisted of two parts:
1) Clinical comparative cross section study
2) Experimental study
The study was conducted in Zagazig University, Faculty of Medicine in the duration from 1st of October 2015 to 31th of December 2015. Twenty workers (employees and instructors) in the gross anatomy laboratory (lab), for more than one year, and 20 librarians were included in this study.
The inclusion criteria included: Adults’ ≥21 and ≤50 years old spent at least one year working regularly in gross anatomy lab or library with normal routine laboratory investigation such as blood sugar, lipid profile (cholesterol, triglyceride, HDL and LDL), kidney function test and liver function test.
- Absence of any gross abnormality in medical examination with normal pulse, blood pressure, heart rate and temperature.
- Chest, heart, abdomen and neurological examinations are clinically free.
- No manifestations of epidemic or endemic infections.
The exclusion criteria included substance abuse, hepatic or renal disease, malignant tumor, surgery within 6 month, neurodegenerative disorder, any medical disorder such as hypertension, diabetes and any previous history or present history of psychiatric disorders.
This study was carried out within the ethics of scientific research and an ethical approval for this study was obtained from the Institutional Review Board of Zagazig University, faculty of medicine, the approval number ZU-IRB #4045-2-9-2015. All subjects were fully informed about the nature and objectives of this study and a written informed consent was taken from them. All data are confidential and used only for the research purpose and they were not exposed to any harm or risk.
All participants underwent:
・ A standardized clinical assessment: including medical, neurological and psychiatric examination.
・ Mini-Mental state examinations [
・ Hostility Quantity and Hostility Direction Questionnaire (H-Q-H-D) [
・ Middlesex hospital questionnaire (MHQ) [
The study was conducted using adult albino rats. Females’ hormones have an effect on the results [
A total of 40 male rats were divided randomly into four groups. Group I (control) received an intraperitoneal (ip) injection of normal saline every day. The rats in Group II received 10 mg/kg of formaldehyde ip once daily for 14 days concentration 36.6% to 38% in water [
At the end of the two weeks experimental period, all of the rats were scarified and their brains (frontal and hippocampus) were obtained for histological examination and biochemical analysis.
Many people cannot freely eat fresh raw garlic (FRG) because of its intense taste and smell even though they know that garlic is good for their health. In addition, the consumption of FRG is often associated with several health hazards, such as stomach and digestion problems [
So, we decided to use garlic juice in this study for easy preparation, administration and to avoid any gastric problem to rats.
To prepare garlic juice, garlic bulbs were separated, peeled and washed with distilled water. After drying in a shed, the clean garlic bulbs were crushed with an electric grinder and the extract was decanted carefully through muslin cloth [
・ Brain tissue Sampling
At the end of the study, the rats were euthanized by decapitation and their brains (frontal and hippocampus) were taken. Each brain was divided into two parts; one was flash frozen in liquid N2 and stored at -80˚C for later use in measures of malondialdehyde (MDA) and reduced glutathione (GSH) contents, superoxide dismutase (SOD) activities and nitric oxide (NO) level. The other part was processed for histologic examination.
・ Biochemical Study
Reduced glutathione (GSH) contents in the brain were assessed according to the method of Ahmed et al. [
Brain Tissue SOD activity was measured according to the method of Nishikimi et al. [
Brain contents of MDA (indices of lipid peroxidation) were determined spectrophotometrically using a commercial kit (DokkiBiodiagnostic, Giza, Egypt). Briefly, an aliquot of tissue extract supernatant was mixed with 1 ml 5% trichloroacetic acid and then centrifuged at 2500 ×g for 10 minutes. Supernatant (0.2 ml) was transferred to a test tube and then 0.2 ml of 8.1% sodium dodecyl sulfate (SDS), 1.5 ml of 30% acetic acid (pH = 3.5) and 1.5 ml of 0.8% thiobarbituric acid (TBA) were added. The tube was mixed, covered with glass beads, heated in water bath (at 95˚C) for 30 minutes and then cooled. After centrifugation (4000 ×g, 10 min), the supernatant was isolated and absorbance of the pink color was measured at 532 nm in Model UVD-2950 scanning spectrophotometer (Labomed Inc., Los Angeles, CA). A standard curve was generated using 1,1,3,3-tetraethoxypropane; from this curve, MDA levels in each sample were extrapolated. All data were expressed as nmol MDA/g tissue processed, Ohkawa et al. [
Nitric oxide (NO) was determined using colorimetric assay where nitrate is converted to nitrite via nitrate reductase. Griess reagent then act to convert nitrite to a deep purple azo compound that can be determined using spectrophotometer [
・ Histopathological Examinations
Brain tissues were embedded in paraffin wax and cut into sections (3 - 5 μm thickness) and stained with haematoxylin and eosin (H and E). Examination of the stained tissue sections was done by a pathologist, who was blinded to the protocol of the study.
・ Statistical Analysis
Continuous variables are reported as means with SD if normally distributed, an independent t test used for comparing two groups and An ANOVA with Tukey Kramer’s test used for multiple comparisons. Qualitative data were represented as frequencies and percentages, Chi-square test (χ2) and fisher exact test were used for comparing groups. The test results were considered significant when p-value < 0.05 and all p values were two-tailed. Data were analyzed using Statistical Package of Social Science (SPSS), software version 16.0 [
Regarding sociodemographic characteristics, both FA-exposed persons (gross anatomy Lab. workers) and control group (librarians) were matched for age, gender, educational level and marital status (table 1).
Clinical assessment of both groups revealed that the most common physical symptom reported by FA-exposed group was: easy fatigability, headache, excessive sleep, anorexia, eye irritation, excessive lacrimation, chest tightness and cough.
Mini-mental state examination in the present study revealed that, FA-exposed persons were more cognitively impaired than control group (24.95 ± 3.4 and 27.2 ± 2.6 p = 0.03) respectively (figure 1).
Middlesex hospital questionnaire (MHQ) of studied groups had shown a statistically significant difference between the two groups. FA exposed group suffered from more anxiety, somatization and depression (table 2).
Hostility Direction and Hostility Quantity Questionnaire (HDHQ) revealed that FA exposed group was more hostile than control group. The direction of hostility in FA exposed group was more toward outside than control group (table 3).
There was a non statistical significant difference between the control group and garlic treated groups as regard superoxide dismutase (SOD) activities, reduced glutathione (GSH), malondialdehyde (MDA) and nitric oxide level in brain tissue (
So the negative control group was chosen to compare with the FA treated group and formaldehyde and garlic treated group.
Mean values of SOD and GSH show high statistical significant decrease While MDA and NO level show high statistical significant increase in formaldehyde treated group when compared with control group (
p value | test | Librarians (control) | Gross Anatomy lab workers (FA-exposed ) | |
---|---|---|---|---|
0.61 | 0.509* | 23 - 54 36 ± 5.972 | 25 - 50 35 ± 6.451 | Age (years) Mean ± SD |
0.25 | 1.16* | 1 - 30 16.5 ± 2.601 | 1 - 26 15.5 ± 2.853 | Duration of work (years) Mean ± SD |
0.507 | 0.44** | N. (%) 12 (60.0) 8 (40.0) | N. (%) 14 (70.0) 6 (30.0) | Sex Male Female |
0.31 | 1.03** | 12 (60.0) 8 (40.0) | 15 (75.0) 5 (25.0) | Marital state Married Non married |
0.34 | 3.37** | 4 (20.0) 9 (45.0) 5 (25.0) 2 (10.0) | 7 (35.0) 10 (50.0) 3 (15.0) 0 (0.0) | Education Basic Secondary High Postgraduate |
SD: Standard Deviation; N. (%): Number (percent); *student t tests for quantitative variables; **chi square test for qualitative variables.
P vlue | t test | Librarians (control) Mean ± SD | Gross Anatomy lab workers (FA-exposed) Mean ± SD | |
---|---|---|---|---|
0.001** | 3.44 | 2.15 ± 1.01 | 3.95 ± 2.11 | Free-floating anxiety |
0.68 | 0.405 | 2.31 ± 1.17 | 2.45 ± 1.01 | Phobia |
0.76 | 0.304 | 5.15 ± 2.65 | 4.9 ± 2.55 | obsessions |
0.004* | 3.06 | 3.95 ± 2.01 | 6.55 ± 3.22 | Somatization |
0.002* | 3.43 | 3.40 ± 1.64 | 5.95 ± 2.89 | Depression |
0.32 | 1.007 | 4.28 ± 1.44 | 4.75 ± 1.51 | Hysteria |
SD: Standard Deviation; t test: Student t test; *: Significant (P < 0.05) **: Highly?significant (P < 0.001).
P value | t test | Librarians (control) Mean ± SD | Gross Anatomy lab workers (FA-exposed) Mean ± SD | |
---|---|---|---|---|
0.002* | 3.29 | 3.10 ± 1.12 | 4.35 ± 1.28 | Self-criticism |
<0.001** | 5.078 | 1.3 ± 0.63 | 2.7 ± 1.06 | Paranoid hostility |
0.006* | 2.88 | 3.15 ± 1.41 | 4.65 ± 1.85 | Acting out |
0.009** | 2.75 | 4.5 ± 1.91 | 6.25 ± 2.11 | Criticism of others |
0.002* | 3.39 | 2.75 ± 1.1 | 4.15 ± 1.48 | Guilt feeling |
0.046* | 2.06 | 15.65 ± 6.66 | 19.85 ± 6.24 | Total hostility degree |
0.013* | 2.62 | 0.95 ± 5.01 | -2.75 ± 3.86 | Direction of hostility |
SD: Standard Deviationt; t test: Student t test; *: Signifiant (P < 0.05); **: Highly significant (P < 0.001).
Parameter in brain tissue | Negative control group (I) Mean ± SD | Garlic treat group (III) Mean ± SD | t test | P value |
---|---|---|---|---|
SOD (U/L) | 64.46 ± 5.72 | 64.34 ± 5.35 | 0.048 | 0.96 |
GPx (ng/ml) | 28 ± 4.62 | 27.81 ± 4.57 | 0.093 | 0.93 |
MDA (mmol/l) | 98.35 ± 8.99 | 97.85 ± 5.07 | 0.15 | 0.88 |
Nirtric oxide (µmol/g) | 45.84 ± 2.08 | 45.99 ± 2.04 | 0.16 | 0.87 |
SD: Standard Deviation. Number of sacrificed rats for each group was 10 rats. t test: Student t test; SOD: Superoxide dismutase; GPx: Glutathione peroxidase; MDA: Malondialdehyde.
Parameter in brain tissue | Negative control group (I) Mean ± SD | FA treated group (III) Mean ± SD | FA and Garlic treated group (IV) Mean ± SD | ANOVA | P value |
---|---|---|---|---|---|
SOD (U/L) | 64.46 ± 5.72 | 28.85 ± 2.56a | 50.88 ± 6.02a,b | 128.311 | <0.0001** |
GPx (ng/ml) | 28 ± 4.62 | 10.62 ± 1.6a | 20.54 ± 5.77a,b | 39.873 | <0.0001** |
MDA (mmol/l) | 98.35 ± 8.99 | 402.34 ± 4.9 a | 115.48 ± 5.18a,b | 6645.477 | <0.0001** |
Nirtric oxide (µmol/g) | 45.84 ± 2.08 | 109.56 ± 3.05 | 65.03 ± 4.17a,b | 1033.506 | <0.0001** |
Number of sacrificed rats for each group was 10 rats. SD: Standard Deviation; ANOVA: Analysis of variance; **: Highly?significant (P<0.001); a = significant versus control group; b = significant versus formaldehyde treated group; SOD: Superoxide dismutase; GPx: Glutathione peroxidase; MDA: Malondialdehyde.
In formaldehyde and garlic treated group SOD and GSH show high statistical significant increase while MDA and NO show high statistical significant decrease when compared with formaldehyde treated group (
Specimen from brain of both control and garlic treated group showing few granular cells and pyramidal cells with vesicular nuclei, basophilic cytoplasm and processes. The surrounding neuropil contains nerve fibers and blood vessels (
While specimens from brain of formaldehyde treated rats’ revealed histopathological changes in the brain by light microscope which revealed many distorted cells with deeply stained shrunken nuclei and cytoplasm surrounded by vacuolated pale areas. Few pyramidal cells appeared normally (
Formaldehyde is widely used chemical compound in industrial field. It’s a member of the aldehyde family and one in all the simplest organic molecules. FA is taken into account as a typical indoors and outdoors waste matter [
employee (him or her) to the potential threat [
Neurotoxicity is any effects on the structure or function of both the central and/or peripheral nervous system. The nervous system is of particular important as mature neurons are incapable of regeneration [
Our study is a trial to evaluate the neuropsychiatric sequel to chronic FA exposure and the role of garlic (as antioxidant) in protection from FA-induced neurotoxicity your paper.
Both FA-exposed persons (gross anatomy Lab. workers) and control group (librarians) were matched for several factors like age, gender, educational level and marital status. Clinical assessment of both groups revealed that, the most common physical symptom reported by FA-exposed group was: easy fatigability, headache, excessive sleep, anorexia, eye irritation and excessive lacrimation, chest tightness and cough. These results came closely in agreement with those obtained by [
Mini-mental state examination in the present study revealed that, FA-exposed persons were more cognitively impaired than control group. Four FA-exposed persons suffered from mild cognitive impairment (18 - 23) [
Tong et al. [
Also, exogenous formaldehyde exposure causes human cognitive impairment and animal memory loss; furthermore many studies proved that formaldehyde at pathological levels induces Aβ deposition and misfolded tau protein to form globular amyloid-like aggregates [
Middlesex hospital questionnaire (MHQ) of studied teams had shown a statistically important distinction between the 2 teams. FA exposed team suffered from additional anxiety, somatization and depression. Epidemiological studies have shown that work-related exposure to FA leads to headaches, fatigue, anxiety, sleep disorders, and particularly cognitive disorders [
The study of hostility within the studied teams by, Hostility Direction and Hostility quantity questionnaire, discovered that, formaldehyde-exposed cluster were additionally hostile than control cluster. The direction of hostility in formaldehyde-exposed cluster was higher toward outside than control cluster. Self-criticism, paranoid hostility, acting out hostility, criticism of others were statistically higher among formaldehyde-exposed cluster as compared to controls. The results of animal experiments reveal that inhaled formaldehyde induces abnormal behaviors, such as: aggression, depression, a decline in movement activity, and spatial memory deficits [
We examined the toxic effects of exposure to FA on the brain (hippocampus and frontal cortex) of adult male albino rats and the role of garlic to minimize these effects.
Many studies have discussed the toxic effects of FA on the central nervous system [
FA, which causes an increase in cytotoxic effects by compromising the intracellular balance, has a tendency to bind with proteins, nucleic acids and unsaturated fatty acids. These combinations lead to inflammatory reactions, allergic reactions, cytotoxicity, necrosis, mutagenesis and carcinogenesis by proteins denaturation. In addition, increase of free oxygen radicals in the FA exposed tissues and acceleration of apoptosis that cause cell death [
In the present study, Formaldehyde showed decrease in the endogenous antioxidant system (glutathione peroxidase; GSH and superoxide dismutase; SOD). In contrast, malondialdehyde (MDA) activity, and nitric oxide (NO) levels were significantly increased.
In line with our results, numerous studies have stated that, formaldehyde (FA) exposure causes neuronal damage with oxidative stress which is considered as one of the most critical mechanism of its toxicity [
Chang and Xu [
The research of Zhang et al. [
Our study showed increase in level of NO; an explanation for this increment comes from Tang et al. [
As a result of the above-mentioned toxic effects of FA on the brain, and that, oxidative stress is one of the proposed mechanisms, so, it was crucial to develop effective therapeutic drugs and strategies that could reverse FA induced-neuro- toxicity. The use of different antioxidants as selenium [
The effectiveness of garlic has been related to its potent antioxidant properties [
The present study investigated the results of fresh garlic juice, as a potent protector, on FA-induced neural injury and oxidative stress within the rat brain tissue. Bagheri et al. [
In our study, there was significant decrease in the levels of lipid peroxidation (LPO) in the brain tissue of FA and garlic treated rats compared to FA-treated rats. Moreover, the level of GSH, SOD, GPx decreased significantly in the garlic and FA-treated group compared to FA-treated rats. While MDA, NO were significantly increased.
The histological results of this study showed that garlic has a protective effect against FA-induced neuronal damage. The intensity of neurodegenerative changes was less in combined FA and garlic treated group than that in the FA-treated group.
Garlic extract components such as S-allyl-L-cysteine (SAC) have neuroprotective effects against reactive oxygen species (ROS) mediated neuronal cell damages [
It is observed that aqueous garlic extract acts as an antioxidant by scavenging ROS, enhancing cellular antioxidant enzymes (e.g superoxide dismutase, Catalase, Glutathione peroxidase), inhibiting peroxidation of lipid and activation of oxidant induced transcription factors [
Garlic contains a number of sulfur and phenolic compounds, which is considered as an excellent antioxidant with antimicrobial action [
Sulfur containing compounds, especially alliin and allicin are considered as the most characteristic constituents of garlic. The amino acid, alliin, is the most representative sulfur compound in fresh garlic, and is converted to allicin by alliinase enzyme when garlic is crushed [
Garlic juice as associate inhibitor candidate, scavenges the ROS, stimulate cellular antioxidant enzymes. These effects are due to the presence of sulfur-containing amino acids and compounds having free carboxyl (C=0) and amino (NH2) contents in their structures [
Clinical and psychiatric profile of FA-exposed persons revealed cognitive impaired anxious and depressed persons. There were hostile persons with more hostility toward outside. These profiles of personality arouse dangerous affairs about the toxic impact of FA on persons, family, and society. Formaldehyde-induced neuronal damage, oxidative stress and lipid peroxidation in frontal and hippocampal brain tissue were minimized by addition of garlic.
Complete prevention of FA exposure is impossible so it is recommended to minimize exposure during Lab work by following the Safety Guidelines as regular air monitoring, maintaining high room air exhaust rates, and using personal protective equipment. Also, early detection of neurotoxic effects in worker exposed to FA and we should encourage research for both new effective prophylactic and therapeutic drugs that could reverse or alleviate FA-induced neurotoxicity.
No conflict of interest related to this article is to declare
Soliman, W.I., Shalaby, N.M.M., Al-sayed, H.M. and Ibrahim, M.H. (2018) Clinical and Experimental study of the toxic Neuropsychiatric effects of formaldehyde exposure: Has garlic a protective role? Occupational Diseases and Environmental Medicine, 6, 1-22. https://doi.org/10.4236/odem.2018.61001