Fig. 3. Effect of intraamygdala β-FNA on the antiallodynic effects of heroin. Saline (A ) or 2.5 nmol of β-funaltrexamien (β-FNA) (B ) was injected bilaterally into the lateral amygdala, and heroin was administered intravenously 24 h after treatment. Paw-withdrawal threshold (PWT) was determined using von Frey filaments before and 3 min after injection of each dose of heroin (mean and 95% confidence intervals are shown). n = 7 (saline) and 6 (β-FNA). *Significantly different from PWT obtained before β-FNA or saline treatment, P ≤ 0.05.