Neuronal activation in orbitofrontal cortex subregions: Cfos expression following cue-induced reinstatement of cocaine-seeking behavior.

Abstract

Cocaine-use disorders are characterized by repeated relapse to drug-seeking and drug-taking behavior following periods of abstinence. Former drug users display increased activation of the orbitofrontal cortex (OFC) in response to drug-related cues, and similar phenomena are also observed in rodent models of drug relapse. The lateral, but not medial, OFC functionally contributes to the maintenance of cue-drug associations; however, less is known about the role of the ventral OFC in this process. To examine the pattern of neuronal activation in OFC subregions in response to drug-associated cues, rats were trained to respond on a lever for a cocaine infusion paired with a complex cue (2-hr sessions, minimum 10 days). Cocaine self-administration was followed by extinction training, in which lever responses resulted in no consequences (2-hr sessions, minimum 7 days). During a 1-hr reinstatement test, drug-seeking behavior (i.e., responses on the drug-paired lever) was examined in the presence or absence of contingent drug-paired cues (Cue TEST vs. Ext TEST, respectively). Rats were overdosed with a ketamine + xylazine cocktail 30-min post session, and transcardially perfused with 4% paraformaldehyde. Cfos protein expression was utilized to measure potential changes in neural activation between the reinstatement test groups. An increase in the number of Cfos-Immunoreactive cells was observed in the ventral and lateral subregions of the OFC in the Cue TEST group. The present findings provide evidence that the ventral and lateral regions of the rat OFC display similar patterns of neuronal activation in response to cocaine-paired cues.

SimpylCellCounter: An Automated Solution for Quantifying Cells in Brain Tissue

“…We utilized a previously published data set in which the number of Cfos-IR cells was increased with exposure to cocaine-associated cues 22 . Male Sprague-Dawley rats (Envigo Inc, Haslett, MI, N=20) were housed under reversed lighting conditions (lights off 7am, on 7pm) and were fed 20-25g of standard irradiated rodent chow with water available ad libitum .…”

“…Following 5 days of recovery, rats underwent cocaine self-administration and extinction training, followed by drug-seeking tests without cue (EXT) or with cue presentation (TEST). After tests, rats were sacrificed and perfused, brains were extracted and cryoprotected and sectioning and image processing was conducted as previously described 22 . We obtained a total of 192 images of Cfos-stained sections from lateral and ventral OFC (lOFC, vOFC respectively) from six bregma points spanning the A-P axis (+5.12 to +3.72), from which Cfos-IR cells were quantified 22 .…”

“…After tests, rats were sacrificed and perfused, brains were extracted and cryoprotected and sectioning and image processing was conducted as previously described 22 . We obtained a total of 192 images of Cfos-stained sections from lateral and ventral OFC (lOFC, vOFC respectively) from six bregma points spanning the A-P axis (+5.12 to +3.72), from which Cfos-IR cells were quantified 22 . In the current study, we compared counts that were previously analyzed manually, with the automated methods OCFU, IMJM and SCC.…”

SimpylCellCounter: an automated solution for quantifying cells in brain tissue

“…We utilized a previously published data set in which the number of cFos-IR cells was increased with exposure to cocaine-associated cues 23 . Male Sprague-Dawley rats (Envigo Inc, Haslett, MI, N = 20) were housed under reversed lighting conditions (lights off 7 am, on 7 pm) and were fed 20-25 g of standard irradiated rodent chow with water available ad libitum.…”

“…We chose OCFU and IMJM due to the similarities between cFos-IR cells and the cell colony images analyzed in their respective publications. We used 192 images of cFos-IR cells from the orbitofrontal cortex (OFC) of rats that underwent a cue-induced reinstatement paradigm where previous drug-paired cues elicited increased drug-seeking behaviors 23 . We tested various metrics of performance between OCFU, IMJM and SCC and found that SCC quantified cFos-IR cells with high accuracy when compared with manual analysis.…”