Spread of Muscle Hyperalgesia and Pain in a Low Dose NGF-induced Pain Model

Spread of Muscle Hyperalgesia and Pain in a Low Dose NGF-induced Pain Model

The purpose of this study is to investigate and determine the time course and distribution on muscle hyperalgesia and muscle pain in a repeated, low dose NGF model. It is hypothesized that low dosages i.m injections of NGF are able to induce mechanical hyperalgesia and muscle soreness in a same manner (effect of duration) as for dosages previously used in NGF studies. Furthermore, it is also speculated if several injections of low dose NGF into the muscle combined are able to course immediate pain sensation and spreading of muscle hypersensitivity.

Effects of pain responses, symptom development and pattern (time course and distribution) following 5 i.m low dose injections of NGF injected into the tibialis anterior muscle will be compared to a high dose i.m injection of NGF injected into the contralateral side in healthy pain-free subjects.

Inclusion Criteria:

• Healthy and pain free volunteers

Exclusion Criteria:

• Pregnancy
• Drug addiction defined as the use of cannabis, opioids or other drugs
• Previous neurologic, mental illnesses, or psychiatric diseases.
• Past history of chronic pain in the musculoskeletal system (muscle, joint, cartilage, connective tissue)
• Participation in other pain trials throughout the study period
• Lack of ability to cooperate
• Taking any analgesic 24 hours before the injections
• Performing any strenuous leg exercise through out the study period causing sore muscles