Cerebral cortex and hippocampus respond differently after post-natal exposure to uranium.
The central nervous system (CNS) is known to be sensitive to pollutants during its development. Uranium (U) is a heavy metal that occurs naturally in the environment as a component of the earth's crust, and populations may therefore be chronically exposed to U through drinking water and food. Previous studies have shown that the CNS is a target of U in rats exposed in adulthood. We assessed the effects of U on behavior and cholinergic system of rats exposed from birth for 10 weeks at 10 mg.L⁻¹ or 40 mg.L⁻¹. For behavioral analysis, the sleep/wake cycle (recorded by telemetry), the object recognition memory and the spatial working memory (Y-maze) were evaluated. Acetylcholine (ACh) and acetylcholinesterase (AChE) levels were evaluated in the entorhinal cortex and hippocampus. At 40 mg.L⁻¹, U exposure impaired object recognition memory (-20%), but neither spatial working memory nor the sleep/wake cycle was impaired. A significant decrease was observed in both the ACh concentration (-14%) and AChE activity (-14%) in the entorhinal cortex, but not in the hippocampus. Any significant effect on behaviour and cholinergic system was observed at 10 mg U.L⁻¹. These results demonstrate that early exposure to U during postnatal life induces a structure cerebral-dependant cholinergic response and modifies such memory process in rats. This exposure to U early in life could have potential delayed effects in adulthood.
Institut de RadioProtection et de Sûreté Nucléaire, Pôle de la Radioprotection de l'Homme, Service de Radiobiologie et d'Epidémiologie, Laboratoire de Radiotoxicologie Expérimentale.
Philippe
P
Lestaevel
Hélène
H
Bensoussan
Bernadette
B
Dhieux
Olivia
O
Delissen
Claire-Marie
CM
Vacher
Isabelle
I
Dublineau
Philippe
P
Voisin
Mohammed
M
Taouis
D000109:Acetylcholine / Q000378:metabolism*; D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism* / Q000503:physiopathology; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008568:Memory / Q000187:drug effects*; D011848:Radioactive Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012890:Sleep / Q000502:physiology; D014501:Uranium / Q000008:administration & dosage / Q000633:toxicity*; D014851:Wakefulness / Q000502:physiology
D011848:Radioactive Pollutants; D014501:Uranium; D000110:Acetylcholinesterase; D000109:Acetylcholine