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Table 2 Sex differences in opioid analgesia and addiction in animals

From: Sex differences in opioid analgesia and addiction: interactions among opioid receptors and estrogen receptors

Opioid

Receptor

Species

Model

Effect

Reference

Buprenorphine

ORL1 agonist

Rat

Hot plate

M = F

[72]

MOR partial agonist

Tail withdrawal

M > F

[73–75]

KOR antagonist

   

M = F

[72]

Temporal summation (thermal stimulus / tail withdrawal)

M > F

[76]

Butorphanol

MOR partial agonist

Rat

Capsaicin-induced hyperalgesia (Tail withdrawal)

M = F

[77]

KOR agonist

Temporal summation (thermal stimulus / tail withdrawal)

M > F

[76]

Fentanyl

MOR agonist

Rat

Tail flick

M = F

[78]

Methadone

MOR agonist

Rat

Tail flick

M > F

[79]

Morphine

MOR agonist

Rat

Abdominal constriction

M > F

[80, 81]

KOR agonist

Hot plate

M > F

[81]–[86]

DOR agonist

 

M < F

[87]

Tail flick

M > F

[76, 81, 88–94]

M = F

[95]

Tail withdrawal

M > F

[74, 75, 85, 86]

Temporal summation (thermal stimulus / tail withdrawal)

M > F

[96]

Mouse

Hot plate

M > F

[97–99]

Tail Flick

M > F

[100]

Tail Withdrawal

M > F

[101, 102]

M = F

[101]

M < F

[101]

Nalbuphine

KOR agonist

Rat

Tail withdrawal

M > F

[74, 103, 104]

MOR antagonist

Heroin

MOR agonist

Rat

Acquisition of self-administration

M < F

[105–107]

KOR agonist

DOR agonist