Table 3.
Pain relieving effect of PEA—mainly given via intraperitoneal route—in animal models of chronic inflammatory pain. Summary of studies in chronological order.
| Animal Model | Main Behavioural Effect | Ref. |
|---|---|---|
| Somatic Inflammatory Pain | ||
| Carrageenan-induced hyperalgesia | Significant reduction of mechanical hyperalgesia | [179] |
| Formalin-induced persistent somatic pain | Significant inhibition of both early and late phases of formalin-evoked pain behaviour |
[144] |
| Formalin-induced persistent somatic pain | Significant reduction of the second phase behavioural response (composite pain score) |
[180] |
| Formalin-induced persistent somatic pain | Marked inhibition of pain behaviour | [174] |
| Carrageenan-induced hyperalgesia | Abolishment of hyperalgesic response | [181] |
| Intraplantar NGF-induced hyperalgesia | Significant reduction of hyperalgesia and neutrophil accumulation |
[189] |
| Carrageenan-induced hyperalgesia | Marked time-dependent reduction of mechanical hyperalgesia | [183] |
| Carrageenan-induced hyperalgesia (s.c. sponge implant) | Significant reduction of new nerve formation and decrease of granuloma-associated hyperalgesia |
[184] |
| Carrageenan-induced hyperalgesia | Significant increased mechanical and thermal thresholds (anti-hyperalgesic effect) | [202] |
| Formalin-induced nociception |
Dose-dependent reduction of nocifensive behaviour in both early and late phases | [202] |
| Formalin-induced neuropathic-like behaviour |
Significant and dose-dependent decrease of mechanical allodynia and thermal hyperalgesia | [185] |
| Oxaliplatin-induced neuropathic pain |
Significant decrease of hyperalgesia and allodynia and improvement in motor coordination |
[176] |
| Streptozotocin-induced diabetic neuropathy |
Dose-dependent and significant relief of mechanical allodynia | [186] |
| Formalin-induced persistent somatic pain | Significant attenuation of the first and early second phases of nociceptive behaviour |
[132] |
| Carrageenan-induced hyperalgesia | Significant reduction of thermal hyperalgesia by 57% (superior effect compared to meloxicam) |
[187] |
| CFA-induced joint pain | Significant decrease of extravasation and mechanical allodynia | [175] |
| Formalin-evoked persistent somatic pain | Significant attenuation of mechanical allodynia and heat hyperalgesia (over 90%) | [201] |
| Visceral Inflammatory Pain | ||
| Turpentine inflammation of the urinary bladder |
Significant attenuation of the vesical hyper-reflexic response |
[180] |
| Acetic acid-evoked writhing | Dose-dependent attenuation of the writhing response | [174] |
| Turpentine inflammation of the urinary bladder |
Dose-dependent attenuation of referred hyperalgesia | [188] |
| Kaolin-evoked writhing | Potent inhibition of the nocifensive response | [174] |
| Magnesium sulphate-evoked writhing | Dose-dependent inhibition of the nocifensive response | [174] |
| NGF-induced inflammation of the urinary bladder |
Significant increase of micturition threshold | [182] |
| PPQ-induced persistent visceral pain | Dose dependent inhibition of visceral pain measured as stretching movement inhibition | [190] |
| Cyclophosphamide-induced cystitis |
Significant decrease of the pain score | [191] |
Abbreviations. CFA, Complete Freund’s adjuvant; MIA, monosodium iodoacetate; NGF, nerve growth factor; OA, osteoarthritis; PPQ, phenyl-p-quinone.