Hind paw mechanical allodynia
To evaluate the development of mechanical allodynia, the mice were individually placed in transparent boxes on a wire mesh platform allowing easy access to the right hind paw plantar surface. Filaments of different stiffness were applied to the plantar surface of the hind paw, ranging from 0.07 to 2.0 g (0.07, 0.16, 0.40, 0.60, 1.0, 1.4, 2.0 g). The mechanical threshold was obtained according to the up-and-down paradigm [51].
This paradigm continued for a total of six measurements, or until four consecutive positive or four consecutive negative responses occurred. The mechanical paw-withdrawal threshold (in g) response was then calculated from the resulting scores [18]. To determine the baseline thresholds, the animals were acclimatized for 60 minutes before the test and all animals were assessed before stress induction (baseline values). The mechanical threshold was evaluated on days 1, 3, 7, 10 and 14 days. Hind paw mechanical allodynia was also measured before ST or NST induction (Basal), after ST or NST induction (7 days after), and 1 and 4 hours after BIBN4096BS/vehicle treatment.