Dehydroepiandrosterone (DHEA), an adrenal and neurosteroid hormone with strong neuroprotective and immunomodulatory properties, and ligand for all high-affinity neurotrophin tyrosine kinase receptors (Trk), also exerts important effects on hyperalgesia. Its synthetic, 17-spiro-epoxy analogue, BNN27, cannot be converted to estrogen or androgen as DHEA; it is a specific agonist of TrkA, the receptor of pain regulator Nerve Growth Factor (NGF), and it conserves the immunomodulatory properties of DHEA. Our study aimed to evaluate the anti-nociceptive and anti-inflammatory properties of BNN27 during Complete Freund’s Adjuvant (CFA)-induced inflammatory hyperalgesia in mice. Hyperalgesia was evaluated using the Hargreaves test. Inflammatory markers such as cytokines, NGF and opioids were measured, additionally to corticosterone and the protein kinase B (AKT) signaling pathway. We showed for the first time that treatment with BNN27 reversed hyperalgesia produced by CFA. The effect of BNN27 involved the inhibition of NGF in the dorsal root ganglia (DRG) and the increased synthesis of opioid peptides and their receptors in the inflamed paw. We also found alterations in the cytokine levels as well as in the phosphorylation of AKT2. Our findings strongly support that BNN27 represents a lead molecule for the development of analgesic and anti-inflammatory compounds with potential therapeutic applications in inflammatory hyperalgesia.

During tissue injury or infection, leukocytes are activated to produce proinflammatory mediators, which trigger the immune system to produce anti-inflammatory and analgesic molecules. Our previous studies provide evidence that synthetic microneurotrophins, like BNN27, exert significant analgesic and anti-inflammatory effects during Complete Freund’s Adjuvant (CFA)-induced inflammation and pain. Thus, the aim of the present study was to examine if the effect of BNN27 on inflammatory pain is mediated at least in part by activation of T-lymphocytes. For this purpose, six hr following the injection of CFA, spleens were harvested in PBS, lymphocytes were collected and placed in medium containing concanavalin-A and IL-2 to prompt T-lymphocyte proliferation and differentiation. Cells were then treated with BNN27 at different concentrations and the media and cells were collected for ELISA and PCR assays. The proliferation rate of T-cells was also examined using the MTT assay. Our results showed that BNN27 significantly increased the proliferation of T-lymphocytes. In addition, BNN27 significantly decreased IL-6 and TNF-α protein levels, while it increased the mRNA expression of μ-opioid receptor and opioid peptides PENK and POMC at different time points. Our data demonstrate considerable anti-inflammatory and analgesic effects of BNN27, making it a promising molecule for inflammation and pain management.

During tissue injury or infection, leukocytes are activated to produce proinflammatory mediators, which trigger the immune system to produce anti-inflammatory and analgesic molecules. Our previous studies provide evidence that synthetic microneurotrophins, like BNN27, exert significant analgesic and anti-inflammatory effects during Complete Freund’s Adjuvant (CFA)-induced inflammation and pain. Thus, the aim of the present study was to examine if the effect of BNN27 on inflammatory pain is mediated at least in part by activation of T-lymphocytes. For this purpose, six hours following the injection of CFA, spleens were harvested in PBS and lymphocytes were collected and placed in medium containing concanavalin-A and IL-2 to prompt T-lymphocyte proliferation and differentiation. Cells were then treated with BNN27 at different concentrations and the media and cells were collected for ELISA and PCR assays. The proliferation rate of T-cells was also examined using the MTT assay. Our results showed that BNN27 significantly increased the proliferation of T-lymphocytes. In addition, BNN27 significantly decreased IL-6 and TNF-α protein levels, while it increased the mRNA expression of μ-opioid receptor and opioid peptides PENK and POMC at different time points. Our data demonstrate considerable anti-inflammatory and analgesic effects of BNN27, making it a promising molecule for inflammation and pain management.