In this study, we examined the effect
BRX-220, a co-inducer of
heat shock proteins, in injury-induced
peripheral neuropathy. Following sciatic nerve injury in adult rats and treatment with
BRX-220, the following features of the sensory system were studied: (a) expression of
calcitonin gene-related peptide (CGRP); (b) binding of
isolectin B4 (IB4) in dorsal root ganglia (DRG) and spinal cord; (c) stimulation-evoked release of
substance P (SP) in an in vitro spinal cord preparation and (d) nociceptive responses of partially denervated rats.
BRX-220 partially reverses
axotomy-induced changes in the sensory system. In vehicle-treated rats there is a decrease in IB4 binding and CGRP expression in injured neurones, while in BRX-220-treated rats these markers were better preserved. Thus, 7.0 +/- 0.6% of injured DRG neurones bound IB4 in vehicle-treated rats compared to 14.4 +/- 0.9% in BRX-220-treated animals. Similarly, 4.5 +/- 0.5% of DRG neurones expressed CGRP in the vehicle-treated group, whereas 9.0 +/- 0.3% were positive in the BRX-220-treated group.
BRX-220 also partially restored SP release from spinal cord sections to electrical stimulation of primary sensory neurones. Behavioural tests carried out on partially denervated animals showed that
BRX-220 treatment did not prevent the emergence of mechanical or
thermal hyperalgesia. However, oral treatment for 4 weeks lead to reduced
pain-related behaviour suggesting either slowly developing
analgesic actions or enhancement of recovery processes. Thus, the morphological improvement seen in sensory neurone markers was accompanied by restored functional activity. Therefore, treatment with
BRX-220 promotes restoration of morphological and functional properties in the sensory system following
peripheral nerve injury.