Ethanol attenuates spatial memory deficits and increases mGlu1a receptor expression in the hippocampus of rats exposed to prenatal stress.
BACKGROUND
Although it is generally believed that chronic ethanol consumption impairs learning and memory, results obtained in experimental animals are not univocal, and there are conditions in which ethanol paradoxically improves cognitive functions. In the present work, we investigated the effects of prenatal stress and of chronic ethanol exposure during adulthood on spatial memory in rats.


METHODS
Rats were subjected to a prenatal stress delivered as 3 daily 45-minute sections of restraint stress to the mothers during the last 10 days of pregnancy (PRS rats). After 7 months of ethanol exposure (ethanol 10%, oral intake), memory performances were evaluated in a spatial discrimination test in control and PRS male rats. Then, the oxidative damages and the expression of metabotropic glutamate (mGlu) receptors were assessed in their hippocampus.


RESULTS
Chronic ethanol exposure resulted in a reduced performance in a spatial recognition task in control animals. Unexpectedly, however, the same treatment attenuated spatial memory deficits in rats that had been subjected to prenatal stress. This paradigm of ethanol administration did not produce detectable signs of oxidative damage in the hippocampus in either unstressed or PRS rats. Interestingly, ethanol intake resulted in differential effects in the expression of mGlu receptor subtypes implicated in mechanisms of learning and memory. In control rats, ethanol intake reduced mGlu2/3 and mGlu5 receptor levels in the hippocampus; in PRS rats, which exhibited a constitutive reduction in the levels of these mGlu receptor subtypes, ethanol increased the expression of mGlu1a receptors but did not change the expression of mGlu2/3 or mGlu5 receptors.


CONCLUSIONS
Our findings support the idea that stress-related events occurring before birth have long-lasting effects on brain function and behavior, and suggest that the impact of ethanol on cognition is not only dose- and duration-dependent, but also critically influenced by early life experiences.
Van Waes
Vincent
V
NEUROSTRESS EA 4347, Université Lille Nord de France 59655 Villeneuve d'Ascq, France.
Enache
Mihaela
M
Zuena
Annarita
A
Mairesse
Jérôme
J
Nicoletti
Ferdinando
F
Vinner
Elisabeth
E
Lhermitte
Michel
M
Maccari
Stefania
S
Darnaudéry
Muriel
M
D000818:Animals; D000431:Ethanol / Q000008:administration & dosage*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008569:Memory Disorders / Q000378:metabolism / Q000517:prevention & control*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000096:biosynthesis*; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology; D013315:Stress, Psychological / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D000431:Ethanol