Fig. 2. Spared nerve injury (SNI) surgery induced immediate and long-lasting depressive changes. (A ) Animals after SNI demonstrated increased immobility during the forced swim test, compared with sham-operated rats. *P < 0.05, Student t test. n = 6. (B ) Rats after SNI demonstrated chronic decreases in preference for 1% sucrose solution compared with sham-operated rats. Sucrose preference = volume (sucrose solution)/volume (sucrose solution + water). ***P < 0.001, *P < 0.05, two-way ANOVA with post hoc Bonferroni correction tests. sham: n = 13; SNI: n = 17. (C ) Both SNI-operated and sham-operated rats demonstrated an initial loss of sucrose preference postoperatively (on postoperative day (POD) 2), but this loss of preference only persisted in SNI-operated rats. ***P < 0.001, *P < 0.05, two-way ANOVA with post hoc Bonferroni tests. Naïve: n = 17; sham: n = 17; SNI: n = 19. (D ) Total fluid consumption was not altered with either sham or SNI surgeries. Naïve: n = 4; sham: n = 7; SNI: n = 9.