Fig. 4
Unilateral inhibition of CeA CRF neurons during alcohol withdrawal. a Timeline of the experiment. b Representative images of NpHR-eYFP expression in the CeA. Scale bars = 200 μm (insets = 50 μm). c Time-course of the effect of unilateral optogenetic inactivation of CeA CRF neurons. Rats escalated their alcohol intake after CIE (F6,66 = 9.23, p < 0.001, one-way ANOVA). The escalation of alcohol drinking was observed only on days when the laser was OFF (p < 0.05, vs. BSL, Newman Keuls post hoc test). A two-way repeated-measures ANOVA revealed a significant time ×laser illumination interaction (F2,22 = 13.15, p < 0.001), with a significant reduction of alcohol self-administration when the green laser was ON compared with when it was OFF (p < 0.01, Newman Keuls post hoc test). #p < 0.05, vs. baseline (BSL); **p < 0.01, vs. laser OFF. d Effect of unilateral CeA CRF neuron inhibition on somatic withdrawal signs. The laser ON group exhibited significant decreases in ventromedial limb retraction (Mann–Whitney U = 9.00, p < 0.05) and abnormal gait (U = 3.000, p < 0.01). The sum of the five rating scores revealed a significant decrease in overall withdrawal severity (U = 4.5, p < 0.05) after the inhibition of CeA-CRF neurons. *p < 0.05, vs. laser OFF. e Unilateral optogenetic inhibition of CeA-CRF neurons did not alter saccharin self-administration (t11 = 0.321, p > 0.05, paired t-test). f Inhibition of CRF neurons suppressed withdrawal-induced CeA Fos immunoreactivity (F3,16 = 35.27, p < 0.001, one-way ANOVA). The Newman Keuls post hoc test showed that after unilateral inhibition (laser ON), the withdrawal-induced increase in Fos+ neurons (laser OFF; p < 0.01, laser OFF vs. naive) was completely prevented in the ipsilateral CeA (p < 0.01, laser ON vs. OFF; ##p < 0.01, vs. naive; **p < 0.01, vs. laser OFF) and partially in the contralateral CeA (+p < 0.05, ON/contralateral vs. OFF). g–j Representative pictures of the different experimental conditions that are depicted in e. Scale bars = 200 μm (insets = 50 μm). The data are expressed as mean ± SEM
