Exposure of neonatal rats to alcohol has differential effects on neuroinflammation and neuronal survival in the cerebellum and hippocampus.
BACKGROUND
Fetal alcohol exposure is a leading cause of preventable birth defects, yet drinking during pregnancy remains prevalent worldwide. Studies suggest that activation of the neuroimmune system plays a role in the effects of alcohol exposure during the rodent equivalent to the third trimester of human pregnancy (i.e., first week of neonatal life), particularly by contributing to neuronal loss. Here, we performed a comprehensive study investigating differences in the neuroimmune response in the cerebellum and hippocampus, which are important targets of third trimester-equivalent alcohol exposure.


METHODS
To model heavy, binge-like alcohol exposure during this period, we exposed rats to alcohol vapor inhalation during postnatal days (P)3-5 (blood alcohol concentration = 0.5 g/dL). The cerebellar vermis and hippocampus of rat pups were analyzed for signs of glial cell activation and neuronal loss by immunohistochemistry at different developmental stages. Cytokine production was measured by reverse transcriptase polymerase chain reaction during peak blood alcohol concentration and withdrawal periods. Additionally, adolescent offspring were assessed for alterations in gait and spatial memory.


RESULTS
We found that this paradigm causes Purkinje cell degeneration in the cerebellar vermis at P6 and P45; however, no signs of neuronal loss were found in the hippocampus. Significant increases in pro-inflammatory cytokines were observed in both brain regions during alcohol withdrawal periods. Although astrocyte activation occurred in both the hippocampus and cerebellar vermis, microglial activation was observed primarily in the latter.


CONCLUSIONS
These findings suggest that heavy, binge-like third trimester-equivalent alcohol exposure has time- and brain region-dependent effects on cytokine levels, morphological activation of microglia and astrocytes, and neuronal survival.
Department of Neurosciences, School of Medicine, MSC08 4740, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131-0001, USA. ltopper@salud.unm.edu.
Lauren A
LA
Topper
Department of Neurosciences, School of Medicine, MSC08 4740, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131-0001, USA. bbaculis@salud.unm.edu.
Brian C
BC
Baculis
Department of Neurosciences, School of Medicine, MSC08 4740, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131-0001, USA. fvalenzuela@salud.unm.edu.
C Fernando
CF
Valenzuela
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002492:Central Nervous System Depressants / Q000633:toxicity*; D002531:Cerebellum / Q000473:pathology*; D003213:Conditioning, Psychological / Q000187:drug effects; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004660:Encephalitis / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology; D000431:Ethanol / Q000633:toxicity*; D005239:Fear; D007839:Functional Laterality / Q000187:drug effects; D005684:Gait / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D006624:Hippocampus / Q000473:pathology*; D020287:In Situ Nick-End Labeling; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger; D051381:Rats
D002492:Central Nervous System Depressants; D016207:Cytokines; D005904:Glial Fibrillary Acidic Protein; D012333:RNA, Messenger; D000431:Ethanol