Cannabinoid system physiological effects

1. Cannabinoid system physiological effects • Motor impairement • Memory impairement • Catalepsy • Temperature decrease • Analgesia • Pressure modification • Immune suppression/stimulation

2. Definition of pain and nociception • Pain is “An unpleasent sensory and emotional experience associated with actual or potential tissue damage, or described in term of such damage” IASP 1979 • Nociception is referred to the reception in the central nervous system of signals triggered by the activation of specialized receptors called nociceptors

3. Skin Spinal cord DRG Pain pathway I

4. Pain pathway II

5. Type of pain

6. Preclinical pain models Ethical issues Legislation: Procedures involving animals and their care must be conducted in conformity with the institutional guidelines, in compliance with national and international law • Experiments involving the study of pain on conscious animals must be reviewed by a specific committee; • Is forbidden the use of animals paralyzed with a neuromuscular blocking agent without a general anesthetic or an appropriate surgical procedure that eliminates sensory awareness; • The duration of experiments must be as short as possible, and the number of animals involved must be kept to the minimum.

7. Phasic pain models Tonic pain models Inflammatory pain models Neuropathic pain models Preclinical pain models A. Acute pain: B. Chronic pain:

8. The hot plate test (according to Woolfe and McDonald, 1944) The tail flick test (according to D'Amour & Smith, 1941) Acute pain models Phasic: short-duration stimulus-evoked models

9. Formalin test Pain-like behaviour First phase Second phase Disease models Tonic: short-duration spontaneous models

10. Chronic pain models • 1. Metabolic disfunction STZ-induced diabetic neuropathy • 2. Cancer pain Vincristine-induced neuropathic pain • 3. Infectious disease Varicella zoster virus-induced neuropathy • 4. Neuropathic pain Surgical manipulation of sciatic nerve • 5. Post-tissue injury Injection of an irritant into a joint or hind paw • 6. Inflammatory pain modelInjection of CFA

11. Neuropathic pain models

12. Thermal allodynia (hot) plantar test Mechanical allodynia von Frey hair test Thermal allodynia cold plate test Mechanical hyperalgesia Randall-Selitto Preclinical pain models • Read outs: • Mechanical allodynia • Mechanical hyperalgesia • Cold allodynia • Hot allodynia

13. Cannabinoid and nociception

14. Potential targets for intervention • CB1 and CB2 receptors: • Use of agonists to induce analgesia. • Endocannabinoids internalization: • Blockade of the transporter to elevate the extracellular level of endocannabinoids. • Endocannabinoids degradation • Blockade of the endocannabinoid degrading enzymes (FAAH and/or MAGL) to elevate endocannabinoid extracellular level.

15. CB1 and nociception

16. (Hegyi et al 2009) CB1 localization Spinal cord dorsal horn