Environmental enrichment alters neurotrophin levels after fetal alcohol exposure in rats.
BACKGROUND
Prenatal alcohol exposure causes abnormal brain development, leading to behavioral deficits, some of which can be ameliorated by environmental enrichment. As both environmental enrichment and prenatal alcohol exposure can individually alter neurotrophin expression, we studied the interaction of prenatal alcohol and postweaning environmental enrichment on brain neurotrophin levels in rats.


METHODS
Pregnant rats received alcohol by gavage, 0, 4, or 6 g/kg/d (Zero, Low, or High groups), or no treatment (Naïve group), on gestational days 8 to 20. After weaning on postnatal day 21, offspring were housed for 6 weeks in Isolated, Social, or Enriched conditions. Levels of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) were then measured in frontal cortex, occipital cortex, hippocampus, and cerebellar vermis.


RESULTS
Prenatal alcohol exposure increased NGF levels in frontal cortex (High-dose group) and cerebellar vermis (High- and Low-dose groups); increased BDNF in frontal cortex, occipital cortex and hippocampus (Low-dose groups), and increased NT-3 in hippocampus and cerebellar vermis (High-dose). Environmental enrichment resulted in lower NGF, BDNF, and NT-3 levels in occipital cortex and lower NGF in frontal cortex. The only significant interaction between prenatal alcohol treatment and environment was in cerebellar vermis where NT-3 levels were higher for enriched animals after prenatal alcohol exposure, but not for animals housed under Isolated or Social conditions.


CONCLUSIONS
Both prenatal alcohol exposure and postweaning housing conditions alter brain neurotrophin levels, but the effects appear to be largely independent. Although environmental enrichment can improve functional outcomes, these results do not provide strong support for the hypothesis that rearing in a complex environment ameliorates prenatal alcohol effects on brain neurotrophin levels in rats.
Parks
Elizabeth A
EA
Department of Neurological Surgery, University of California, Davis, California 95616, USA.
McMechan
Andrew P
AP
Hannigan
John H
JH
Berman
Robert F
RF
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism*; D002492:Central Nervous System Depressants / Q000009:adverse effects; D004777:Environment; D000431:Ethanol / Q000009:adverse effects; D005260:Female; D063647:Fetal Alcohol Spectrum Disorders / Q000378:metabolism* / Q000628:therapy; D008098:Litter Size / Q000187:drug effects; D018811:Maternal Exposure; D009414:Nerve Growth Factors / Q000378:metabolism*; D020933:Neurotrophin 3 / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012744:Sex Ratio; D015430:Weight Gain / Q000187:drug effects
D002492:Central Nervous System Depressants; D009414:Nerve Growth Factors; D020933:Neurotrophin 3; D000431:Ethanol