Interference of ethanol and methylmercury in the developing central nervous system.
Studies involving alcohol and its interactions with other neurotoxicants represent the focus of several works of research due to the fact that the use of alcohol can sometimes leads to serious health problems. Fetal exposure to alcohol and mercury has a high incidence in some regions of Brazil, where there are pregnant women who are alcoholics and live in mining areas. This work was conducted to examine the effects of combined exposure to ethanol (EtOH) and methylmercury (MeHg) in rats during the development of the central nervous system (CNS). Experimental behavioral animal models/tests were used in order to examine locomotion, anxiety, depression and memory. Pregnant rats received tap water or EtOH 22.5% w/v (6.5 g/kg per day), by gavage) during pregnancy and breast-feeding. On the 15th day of pregnancy, some groups received 8 mg/kg of MeHg (by gavage). The groups were as follows: control, EtOH, MeHg and EtOH+MeHg. The experimental results showed that the EtOH, MeHg and EtOH+MeHg groups reduced the percentage of frequency and time spent in the open arms entries of the elevated plus-maze (EPM) test, when compared to the control group. This result suggests an anxiogenic behavioral response. The MeHg group increased locomotor activity in the arena and the immobility time in the forced swimming test, suggestive of depression-like behavior. The EtOH+MeHg group showed greater reductions in the percentages of frequency and time spent in the open arms entries in the EPM test, suggesting a sedative-behavior since the frequency of enclosed arm entries was affected. In the inhibitory avoidance task, the EtOH+MeHg group reduced the latency of the step-down response onto the grid floor, suggesting a cognitive and behavior dysfunctions. Taken together, the results suggest that EtOH and/or MeHg intoxication during the developing CNS may be a risk for deficits related to locomotor impairment, anxiety, depression and neurocognitive functions. There is a possibility that EtOH may prevent some of the MeHg responses, but the precise mechanism of action involved in this process needs to be considered for future research.
Maia
Cristiane do Socorro Ferraz
CS
Faculdade de Ciências da Saúde, Curso de Ciências Farmacêuticas, Universidade de Brasília, Distrito Federal 70910-900, Brazil. crismaia@unb.br
Lucena
Greice Maria Rodrigues de Souza
GM
Corrêa
Pollyanna Barbosa Farias
PB
Serra
Raphael Borges
RB
Matos
Robson Willian de Melo
RW
Menezes
Flávia da Cunha
FC
Santos
Setsuko Noro dos
SN
Sousa
João Batista de
JB
Costa
Edmar Tavares da
ET
Ferreira
Vania Maria Moraes
VM
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects* / Q000196:embryology*; D004347:Drug Interactions; D000431:Ethanol / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D008297:Male; D008431:Maternal-Fetal Exchange; D018782:Maze Learning / Q000187:drug effects; D008767:Methylmercury Compounds / Q000008:administration & dosage / Q000032:analysis / Q000633:toxicity*; D009043:Motor Activity / Q000187:drug effects; D011247:Pregnancy; D011270:Pregnancy, Animal; D051381:Rats; D013550:Swimming
D008767:Methylmercury Compounds; D000431:Ethanol; C004925:methylmercuric chloride