Brain derived nerve growth factor induces spinal noradrenergic fiber sprouting and enhances clonidine analgesia following nerve injury in rats.

Many treatments for neuropathic pain activate or augment norepinephrine release in the spinal cord, yet these treatments are less effective against acute nociceptive stimuli. We previously showed in mice that peripheral nerve injury results in sprouting of spinal noradrenergic fibers, possibly reflecting the substrate for this shift in drug efficacy. Here, we tested whether such sprouting also occurs in rats after nerve injury and examined one signal for such sprouting.

Oral donepezil reduces hypersensitivity after nerve injury by a spinal muscarinic receptor mechanism.

Background: Cholinesterase inhibitors which reach the central nervous system produce pain relief but are poorly tolerated because of gastrointestinal side effects. Here, the authors tested whether donepezil, a central nervous system penetrant cholinesterase inhibitor with a low incidence of gastrointestinal side effects, would relieve hypersensitivity in an animal model of neuropathic pain.

Methods: Male rats were anesthetized, and the L5 and L6 spinal nerves were ligated unilaterally.