A study examining innate differences in central urocortin 1 (Ucn1) levels has been conducted between the AA vs. ANA, HAD1 vs. LAD1, HAD2 vs. LAD2 and inbred P (iP) vs. inbred NP (iNP) rat line-pairs (Turek et al., 2005). The Addiction Research Foundation high and low alcohol-consuming (HARF and LARF) rat lines were compared as well, but will not be discussed here. The neuropeptide Ucn1 is related to CRF and binds to both the CRF1 and CRF2 receptors (Bale and Vale, 2004). When the number of Ucn1-positive cells in the Edinger–Westphal nucleus (EWN) was examined, HAD2 rats had greater levels than LAD2 rats, iP rats had lower levels than iNP rats but AA and HAD1 rats did not differ from their low alcohol-consuming counterparts. These differences were confirmed when optical density of Ucn1 immunoreactivity in the EWN was the dependent variable. When the number of Ucn1-positive fibers in the lateral septum was assessed, HAD2 rats had greater levels than LAD2 rats, AA rats had greater levels than ANA rats but HAD1 and iP rats did not differ from their low
