Differential response of glial fibrillary acidic protein-positive astrocytes in the rat prefrontal cortex following ethanol self-administration.

April 1, 2015

Bull C, Syed WA, Minter SC, Bowers MS
2015 Alcohol Clin Exp Res 39(4):650-8. doi: 10.1111/acer.12683. PMCID: PMC4384186.

Background
Prefrontal cortex (PFC) dysfunction is believed to contribute to the transition from controlled substance use to abuse. Because astrocytes have been suggested to play a key role in the development and maintenance of drug-seeking behaviors, we sought to determine whether PFC astrocytes are affected by ethanol (EtOH) self-administration.

Methods
EtOH consumption was modeled in rats by 3 self-administration paradigms where EtOH was made concurrently available with water in the home cage either continuously (CEA) or intermittently (IEA). In the third paradigm, EtOH was only available in the operant chamber (OEA). To avoid the potential confound of acute EtOH effects, all rats were sacrificed after either 24-hour or 3-week abstinence. In all groups, the effect of EtOH consumption on PFC astrocytes was measured using unbiased stereological counting of cells expressing the astrocyte marker glial fibrillary acidic protein (GFAP). GFAP immunoreactivity commonly changes in response to pharmacological insult or injury.

Results
GFAP-positive astrocyte number increased in the prelimbic and anterior cingulate cortex regions of the PFC after IEA. No change was found in the infralimbic or orbitofrontal cortex after IEA. After 3-week abstinence, there was a reduction of astrocytes in the prelimbic and orbitofrontal cortex of the CEA cohort as well as a reduction in the orbitofrontal cortex of the OEA cohort.

Conclusions
These findings demonstrate that discrete PFC subregions contain GFAP-positive astrocyte populations that respond differentially to distinct EtOH consumption paradigms. A better understanding of how specific astrocyte populations uniquely adapt to EtOH consumption could provide insight for targeted therapeutic interventions.