Central NPS administration reverses the cued-fear conditioning deficits of HAB rodents. A, C, E, As a result of acquisition, mHABs (A), rHABs, and rLABs (C, E), but not mLABs (A), showed an increased freezing response to the presentation of the conditioned stimulus (tone). B, D, Twenty-four hours after fear conditioning, intracerebroventricular administration of NPS (1 nmol) 20 min before extinction training completely abolished the expression of cue-conditioned fear in mHABs (B) and facilitated the impaired extinction of conditioned fear in rHABs (D). B, F, Intracerebroventricular administration of an NPSR1-A (10 nmol) did not alter cued fear expression in mLABs (B) or cued fear extinction in rLABs (F). D, F, Neither rHABs nor rLABs showed any freezing to the context on day 2 before the first CS presentation. Data represent the mean ± SEM; numbers in parentheses indicate group size. *p < 0.05, compared with vehicle-treated LAB animals; #p < 0.05 and ###p < 0.001, compared with respective vehicle-treated HAB group. Veh, Vehicle.