Exposure to low levels of fluoride during pregnancy and lactation impairs memory and affects cholinergic neurotransmission in adult rats

GUMILAR F; DOMINGUEZ S; BARTOS M; ESANDI, MC; BRAS C; BOUZAT C; MINETTI A; GALLEGOS C; MONACO N; CANCELA L

Mar del Plata

Congreso; LXI Reunión Científica Annual de la Sociedad Argentina de Investigación Clínica (SAIC); 2016

It is known that exposure to high concentrations of Fluoride (F) produces deleterious health effects in human population. In the last years it has been concluded that low concentrations of F may have adverse health effects as well. Transplacental passage of F and its incorporation into fetal tissues has been demonstrated. Literature is poor on the effects of the exposure to low F doses during pregnancy and lactation on the central nervous system. The purpose of the present study was to evaluate in adult female offspring rats exposed to low F concentrations during pregnancy and lactation, short-term memory (STM), long-term memory (LTM) and expression levels of neuronal 7 nicotinic receptors (nAChR) in hippocampus. Pregnant female rats were exposed to 10 mg/L F in drinking water during pregnancy and lactation. In the 90-day-old offspring, the short-term memory (STM) and long-term memory (LTM) were determined using step-down inhibitory avoidance task. Rats were trained in a step-down inhibitory avoidance paradigm during which stepping-down from a platform presented in a given context was associated with a footshock. Test sessions were carried out 1.5 h (STM) and 24 h (LTM) after training. In the test sessions, the increase in the step-down latency was used as measure of retention. Results show that the exposition to 10 mg/L F during pregnancy and lactation produced in the female offspring a significant impairment in the retention of STM and LTM compared to the control group. mRNA level of 7 nAChR in hippocampus, area involved in memory formation, was determinate by RT-qPCR. We found a significant decrease of 7 nAChR expression in the Fluoride exposed group. In conclusion, the early exposure to low levels of F impairs the retention of memory. Our results suggest that the decrease in the expression of 7 nAChR in hippocampus could be responsible of memory impairment.