Dental Fluorosis and Catalase Immunoreactivity of the Brain Tissues in Rats Exposed to High Fluoride Pre- and Postnatally

Abstract

This study evaluated dental fluorosis of the incisors and immunoreactivity in the brain tissues of rats given chronic fluoride doses pre- and postnatally. Female rats were given drinking water with 0, 30 or 100 ppm fluoride ad libitum throughout gestation and the nursing period. In addition, 63 male offspring were treated with the same water regimens as the mothers after weaning and were followed for 1, 3 or 5 months. The upper and lower incisors were collected, and all teeth were examined under a stereomicroscope and scored by two blinded examiners using a modified rodent enamel fluorosis index. Cortical, hippocampal and cerebellar brain samples were evaluated morphologically and immunohistochemically. All fluoride-treated pups were born with low body weight (p = 0.001). All animals from the fluoride groups had enamel fluorosis with defects of various degrees. The increase in the dental fluorosis scores in the fluoride treatment groups was significant (p < 0.01). The catalase immunoreactivity in the 30- and 100-ppm fluoride groups was significantly higher than that in the controls after 1, 3 and 5 months (p < 0.001). In conclusion, this study showed that rats with dental fluorosis had catalase immunoreactivity in the brain tissues, which may reflect the neurobehavioral toxicity of fluoride.

Association of water fluoride and urinary fluoride concentrations with attention deficit hyperactivity disorder in Canadian youth

“…In particular, both nicotinic acetylcholine receptors and cholinesterase expression appear to play a role in attentional processes ( Levin et al, 2011 ). Other studies have shown morphological changes in neurons ( Bhatnagar et al, 2011 ), mitochondria ( Zhao et al, 2019 ), increased catalase immunoreactivity ( Güner et al, 2016 ), more oxidative stress ( Zhang et al, 2015 ), and increases in apoptotic neurons and abnormal mitochondrial dynamics ( Lou et al, 2013 , 2014 ). Further, some studies have suggested that fluoride may suppress thyroid function ( Trabelsi et al, 2001 ); subclinical hypothyroidism during pregnancy has been linked with increased risk for attention disorders ( Modesto et al, 2015 ; Päkkilä et al, 2014 ).…”

Chronic Exposure to Fluoride Affects GSH Level and NOX4 Expression in Rat Model of This Element of Neurotoxicity

“…Throughout literature, data clearly indicate that exposure to both low and high F-concentrations promotes the synthesis of ROS and malondialdehyde (MDA, a marker of oxidative stress) in the brain [15,16,35,36]. Most studies also confirm that long-term exposure leads to a decrease in the activity of the antioxidant enzymes responsible for maintaining proper redox status in cells, although this depends on fluoride concentration, exposure period, examined brain structures, and animal age [16,37,38].…”

Comparison of fluoride contents in terms of teeth health and water quality in drinking water at the northern and southern regions of Meriç River Basin (Edirne/Turkey)

“…However, health may be adversely affected if excessive amounts are ingested through drinking water. Exposure to fluoride concentrations more than optimal level may result in fluorosis (Güner et al, 2016).…”

“…It is one of the most reactive chemical element which do not exist on its own in the natural environment but rather in the form of fluoride. This element may enter the body through food, water, industrial exposure, drugs and drinking water which is the main source of fluoride intake (75-90% of daily intake) (Güner et al, 2016). Surface waters have fluoride levels less than 0,5 mg/l, while groundwater can contain higher concentrations of fluoride depending on geological condi-tions (Day and Giri, 2016).…”