This transgenic was created by Dr. Bruce Hope at at NIDA IRP and donated to RRRC in 2022. The transgenic rats were created by injecting the cfos-eGFP construct to pronuclei of fertilized eggs obtained from Long Evans females. The 5 prime end of the transgenic DNA construct contained mouse genomic cFos (indluding the promoter and all exon and intron sequences) was fused with eGFP (including poly(A) tail derived from the IRES (phosphorylated-internal ribosomal entry site) of the EGFP Clontech (Cambridge, UK) vector. A single founder animal was identified. All subsequent breeding used hemizygous cfos-GFP male rats paired with wild-type Long Evans female rats obtained from Charles River Laboratories. Rats were bred on Long-Evans background for 13 generations