Antibodies to S100 proteins have anxiolytic-like activity at ultra-low doses in the adult rat

Abstract

S100 proteins are small calcium-binding proteins interacting with numerous intra- and extra cellular targets involved in diverse physiological functions. In particular, S100 proteins may be involved in the regulation of anxiety-related behaviour. In the present study, the effects of affinity-purified antibodies to S100 proteins administered orally at ultra-low doses were evaluated in pre-clinical tests for anxiolytic-like activity in the adult rat. In the Vogel conflict test in the rat, antibodies to S100 proteins increased punished drinking (anti-conflict effect) at 5 and 7.5 mL kg−1, but not at 2.5 or 10 mL kg−1. Antibodies to S100 proteins increased the percentage of entries into the open arms of an elevated plus-maze at 10 mL kg−1, but not at lower doses. Taken together, these results indicate the presence of anxiolytic-like activity for antibodies to S100 proteins over the dose range 5–10 mL kg−1 in the adult rat.