Caudolateral SNr lesions also reduce withdrawal severity after repeated ethanol administration. (a) Bilateral caudolateral SNr-lesioned and sham-lesioned D2 mice were scored for baseline HICs. Lesioned mice (n=12) and one group of sham-lesioned mice (n=17) received three injections of 4 g/kg ethanol at hr 0, 8 and 20. In the second group of sham-lesioned mice, the first and second injections were replaced with saline and ethanol was administered only once at hr 20 (n=6). All mice were tested for HICs hourly beginning at hr 22 and through hr 34. Data represent the mean raw scores ± SEM for baseline and post-ethanol HICs. (b) Repeated episodes of ethanol intoxication and withdrawal significantly enhanced ethanol withdrawal severity (AUC, corrected for baseline HIC scores) compared to acute ethanol withdrawn animals (p<0.05). Mice with bilateral caudolateral SNr lesions displayed significantly less severe ethanol withdrawal than sham-lesioned animals following repeated episodes of ethanol intoxication and withdrawal (p<0.001).