Characterization and evaluation of trpv1 and trpm8 antagonists as potential therapeutic tools for treating pain

Resumo

Although pain is a warning mechanism necessary for the defense against noxious stimuli, occasionally it loses its meaning and becomes pathological (inflammatory or neuropathic pain). Unfortunately, nowadays pathological pain is a global problem that affects a large number of people around the world and, although there are several drugs to treat it, they have undesirable side effects. Luckily, it has been discovered the implication of an ion channels family known as TRP (Transient Receptor Potential) that play an important role in pain transduction. Specifically, it has been shown that TRPV1 and TRPM8 channels are key proteins in pain transduction mechanisms, and through their modulation, analgesic effects might be achieved. Thus, in this thesis we addressed the modulation of these two ion channels looking for new potential modulators that could be develop as analgesics. On one hand, in the first part of the thesis (chapter 1), we investigated the activity of compound triazine 8aA, as an antagonist of TRPV1 channel. We demonstrated its selectivity and specificity, the lack of toxicity in different cell lines and its analgesic and anti-pruritic properties in in vivo pain models. We also present evidence that the mechanism of action is that of an open-channel blocker, showing that it is possible to block TRPV1 with un-competitive modulators, opening new horizons for the next generation of analgesics and anti-pruritic therapies based on TRPV1. On the other hand, in the second part (chapter 2), we addressed the search and characterization of TRPM8 channel antagonists. Using high-throughput screening techniques we found a potent blocker of TRPM8 (compound 8-3) and demonstrated its selectivity and specificity. The structure-activity relationship analysis suggests the minimum elements necessary for the β-lactam scaffold to block the TRMP8 channel activity. In addition, based on docking experiments, we postulated two potential binding sites for this potent, specific and selective TRPM8 antagonist that might help to complete the virtually inexistent literature regarding the mechanisms of action of TRPM8 antagonists.