Chunk #24 — 4. Selectively bred high alcohol-consuming rat lines and their phenotypic characteristics — 4.2. Alcohol-preferring and alcohol-nonpreferring rats
Regarding neurochemical correlates, P rats have lower levels of 5-HT and 5-hydrodxy-indole-acetic-acid (5-HIAA) in cortical and limbic regions than their NP counterparts (Murphy et al., 1982, 1987b). Additionally, there are fewer 5-HT immunostained fibers in the anterior frontal cortex, Acb and parts of the ventral hippocampus in P, compared with NP, rats (Zhou et al., 1991a, 1991b), with the dorsal and median raphe of P rats having fewer 5-HT immunostained neurons as well (Zhou et al., 1991c). P rats have lower levels of DA and its metabolites (DOPAC and HVA) in the Acb and anterior striatum, compared with NP rats (Murphy et al., 1982, 1987b). In addition, P rats have decreased numbers of DA neuronal projections from the ventral tegmental area (VTA) to the Acb, relative to NP rats (Zhou et al., 1995). Regarding accumbal DA, operant self-administration of ethanol was found to increase DA overflow above baseline values to a greater extent in the Acb of P rats than in unselected Wistar rats (Weiss et al., 1993). P rats also have reduced numbers of D2 receptors in the VTA
