Donepezil Reverses Dendritic Spine Morphology Adaptations and Fmr1 Epigenetic Modifications in Hippocampus of Adult Rats After Adolescent Alcohol Exposure

Abstract

These findings indicate that AIE produces long-lasting decreases in dendritic spine density and changes in Fmr1 gene expression in the hippocampal formation, suggesting morphological and epigenetic mechanisms underlying previously reported behavioral deficits after AIE. The reversal of these effects by subchronic, post-AIE donepezil treatment indicates that these AIE effects can be reversed by up-regulating cholinergic function.

Acute Ethanol Produces Ataxia and Induces Fmr1 Expression via Histone Modifications in the Rat Cerebellum

“…The present findings expand upon past research which has linked alcohol to alterations in the molecular and epigenetic landscape in the cerebellum of postmortem AUD subjects (Gatta et al., ) and in the cerebellum of rodents exposed to perinatal EtOH (Guo et al., ; Qi et al., ) or chronic adult EtOH exposure (Auta et al., ). They also expand upon limited recent research illustrating a role for Fmr1 following EtOH exposure, albeit one that was, until now, exclusive to the hippocampus (Mulholland et al., ; Spencer et al., ; Wolfe et al., ). Fmr1 is a dynamic epigenetic target that can alter expression of hundreds of transcripts, but that itself may also be regulated by microRNAs (Kenny et al., ; Liu et al., ; Tan et al., ) or its own noncoding antisense RNA Fxr4 (Pastori et al., ; Peschansky et al., ).…”

“…We also investigated H3K27 acetylation levels at other locations in the Fmr 1 gene where there are CREB binding sites (Mulholland et al., ; Wang et al., ). At the CREB binding site just downstream of the Fmr 1 transcription start site, we found that acute EtOH increased H3K27 acetylation (Fig.…”

“…The resulting DNA–chromatin complex was immunoprecipitated with an antibody directed to acetylated H3K27 (Cell Signaling, #4353). The precipitated DNA was quantified using qPCR with a SYBR Green master mix (BioRad) and primers designed for the Fmr1 promoter (Forward: 5′‐CAC GAC CTG TTA CTA CCC TTT G‐3′, Reverse: 5′‐GGT AAC TGG GCA GAT ACT TTG‐3′), 2 predicted CREB sites (Wang et al., ) at the Fmr1 transcription start site (Forward: 5′‐TCA GCT GCC CAA GAG AGA‐3′, Reverse: 5′‐ACC GGA AGT GAA ACC GAA A‐3′ [site 1]), and just downstream of the transcription start site in the first exon (Forward: 5′‐GGA CGA GAA GAT GGA GGA GC‐3′, Reverse: 5′‐CGG TAG CCC GTT ACC TTG TA‐3′ [site 2]) as well as a distal site in the second intron (Forward: 5′‐GCC ATT CTG CTT TAT TCT AGT TAT ACT C‐3′, Reverse: 5′‐AGT CAG AAT TTG TGG AAA TCT GTT G‐3′ [site 3]), which we previously reported to have altered H3K27 acetylation (H3K27Ac) in the adult hippocampus following adolescent EtOH exposure (Mulholland et al., ). These 4 ChIP primer locations are shown in the Fmr1 gene map (Fig.…”

“…FMRP has recently been implicated in the altered molecular landscape associated with EtOH exposure. Adolescent rats exposed to alcohol showed dendritic spine density deficits, increased Fmr1 mRNA expression, and increased H3K27 acetylation occupancy of the Fmr1 gene in the hippocampus (Mulholland et al., ). This followed the previous reports of altered hippocampal FMRP expression in mice following chronic EtOH vapor treatment (Spencer et al., ).…”

Adolescent Intermittent Ethanol Increases the Sensitivity to the Reinforcing Properties of Ethanol and the Expression of Select Cholinergic and Dopaminergic Genes within the Posterior Ventral Tegmental Area

“…Adolescent alcohol exposure can disrupt this normal remodeling of cortical and limbic regions (Spear, ). Replicable effects of adolescent alcohol consumption on the adult brain include a hyperdopaminergic response to stimuli, reduction in choline acetyltransferase (ChAT), alterations in neuroimmune function, and nonspecific modulation of epigenetic factors (Crews et al., ; Mulholland et al., ; Spear and Swartzwelder, ).…”