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. Author manuscript; available in PMC: 2023 Mar 1.
Published in final edited form as: Addict Neurosci. 2022 Dec 9;5:100057. doi: 10.1016/j.addicn.2022.100057

Fig. 1. Fentanyl vapor leads to detectable blood fentanyl and norfentanyl levels and antinociception.

Fig. 1.

(A) Temporal distribution of noncontingent fentanyl vapor deliveries. (B) Concentration of fentanyl and norfentanyl in blood in male and female mice. Eighteen mice were exposed to 1, 3, or 10 fentanyl vapor deliveries (1.5 s, 60 W) and euthanized 2 min after the last vapor exposure for blood collection. Fentanyl and norfentanyl levels were analyzed by liquid chromatography/tandem mass spectroscopy. The data are expressed as individual points and were analyzed by linear regression (n = 6/number of deliveries). (C) Antinociceptive response to fentanyl vapor self-administration. Male and female C57BL/6J mice were tested in the hot plate test (52.5 °C, 30 s cutoff) immediately before and after the fifth 1-h fentanyl vapor self-administration acquisition session. Fentanyl vapor self-administration increased the latency to a nociceptive response. The data are expressed as the mean ± SEM and were analyzed using paired Student’s t -test. ∗ ∗ ∗ ∗ p < 0.0001. Antinociceptive responses positively correlated with the number of fentanyl vapor deliveries in the self-administration session. The data are expressed as individual points and were analyzed by linear regression. BL, baseline; ACQ, acquisition (n = 16 mice/sex).