The effects of lifelong ethanol exposure and aging on the morphology of the locus coeruleus (LC) were studied in the AA (Alko, Alcohol) and ANA (Alko, Nonalcohol) rats of both sexes. The ethanol-consuming (EtOH) rats were given 12% (v/v) ethanol as the only drinking fluid from 4 to 22 months of age, whereas the young (3-month-old) and aged (24-month-old) controls had only water available. The total LC neuron numbers were obtained by using the unbiased disector method. In the AA line, as we have previously reported. the EtOH female and male rats displayed a 26-30% loss of LC neurons compared with the controls. In the ANA line, the EtOH females had 30% fewer LC neurons than the controls (EtOH 1579 +/- 377 vs. controls 2264 +/- 269, ANOVA p < 0.01), whereas the EtOH males showed no neuron loss compared to the controls (EtOH 1848 +/- 525 vs. controls 2216 +/- 152, ANOVA NS). However, taking into account (sex by line ANCOVA) the markedly higher ethanol intake of the female rats in both lines, no gender or line differences in the ethanol-induced LC degeneration were detected. Neither was there any difference in LC neuron numbers between the young and old control rats of either line of rats. In conclusion, chronic alcohol consumption, not aging per se, damages the LC neurons in experimental animals.