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HIV-associated sensory neuropathy (HIV-SN) is the most frequent manifestation of HIV disease. It often presents with significant neuropathic pain and is associated with previous exposure to neurotoxic nucleoside reverse transcriptase inhibitors. However, HIV-SN prevalence remains high even in resource-rich settings where these drugs are no longer used. Previous evidence suggests that exposure to indinavir, a protease inhibitor commonly used in antiretroviral therapy, may link to elevated HIV-SN risk. Here, we investigated whether indinavir treatment was associated with the development of a "dying back" axonal neuropathy and changes in pain-relevant limb withdrawal and thigmotactic behaviours. After 2 intravenous injections of indinavir (50 mg/kg, 4 days apart), adult rats developed hind paw mechanical hypersensitivity, which peaked around 2 weeks post first injection (44% reduction from baseline). At this time, animals also had (1) significantly changed thigmotactic behaviour (62% reduction in central zone entries) comparing with the controls and (2) a significant reduction (45%) in hind paw intraepidermal nerve fibre density. Treatment with gabapentin, but not amitriptyline, was associated with a complete attenuation of hind paw mechanical hypersensitivity observed with indinavir treatment. Furthermore, we found a small but significant increase in microglia with the effector morphology in the lumbar spinal dorsal horn in indinavir-treated animals, coupled with significantly increased expression of phospho-p38 in microglia. In summary, we have reported neuropathic pain-related sensory and behavioural changes accompanied by a significant loss of hind paw skin sensory innervation in a rat model of indinavir-induced peripheral neuropathy that is suitable for further pathophysiological investigation and preclinical evaluation of novel analgesics.

Original publication

DOI

10.1097/j.pain.0000000000000727

Type

Journal article

Journal

Pain

Publication Date

01/2017

Volume

158

Pages

75 - 85

Keywords

Amines, Analgesics, Animals, Calcitonin Gene-Related Peptide, Calcium-Binding Proteins, Cyclohexanecarboxylic Acids, Disease Models, Animal, Exploratory Behavior, Ganglia, Spinal, Gene Expression Regulation, Glial Fibrillary Acidic Protein, HIV Infections, HIV Protease Inhibitors, Hyperalgesia, Indinavir, Male, Metacarpus, Microfilament Proteins, Microglia, Neuralgia, Pain Measurement, Pain Threshold, Physical Stimulation, Rats, Rats, Wistar, Spinal Cord, Statistics, Nonparametric, gamma-Aminobutyric Acid