Mol Pain
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In a new mouse model for generalized pain syndrome, including fibromyalgia, which used intermittent cold stress (ICS), bilateral allodynia in the hindpaw was observed that lasted more than 12 days; thermal hyperalgesia lasted 15 days. During constant cold stress (CCS), mice showed only a transient allodynia. ⋯ Systemic gabapentin showed complete anti-allodynic effects in the ICS model at the one-tenth dose for injury-induced neuropathic pain model, and central gabapentin showed long-lasting analgesia for 4 days in ICS, but not the injury model. These results suggest that the ICS model is useful for the study of generalized pain syndrome.
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Besides functioning as chemosensors for a broad range of endogenous and synthetic ligands, transient receptor potential vanilloid (TRPV) 1-4 channels have also been related to capsaicin (TRPV1), pain, and thermal stimuli perception, and itching sensation (TRPV1-4). While the expression of the TRPV1-4 genes has been adequately proved in skin, sensory fibres and keratinocytes, less is known about TRPV3 and TRPV4 expression in human blood cells. ⋯ The qRT-PCR assay developed and tested in this study allowed us to determine the relative expression of TRPV1-4 genes in human leukocytes: TRPV3 is the least expressed gene of this pool, followed by TRPV4, TRPV1 and TRPV2. The comparison of TRPV1-4 gene expression between two groups of healthy and hyposensitive subjects highlighted the evident up-regulation of TRPV1, which was almost doubly expressed (1.9x normalized fold induction) in the latter group. All the four house-keeping genes tested in this work (Act-B, GAPDH, hCyPB, HPRT1) were classified as optimal controls and showed a constant expression in human leukocytes samples. We recommend the use of these genes in similar qRT-PCR studies on human blood cells.