Functional Observation Battery Test for Single Intravenous Caffeine Exposure in Male ICR Mice

This study investigated the behavioral responses of male Institute for Cancer Research (ICR) mice to intravenous caffeine exposure via a functional observation battery (FOB) test. Thirty-two experimental mice were randomly assigned to four groups (n = 8 per group) and received intravenous caffeine at a dose of 0, 5, 10, or 20 mg/kg. Functional behaviors were observed at 0, 0.25, 1.5, 6, and 24 h after intravenous caffeine administration. Among the hand-held observations, the ease of removal from the cage and the ease of handling were significantly altered in all caffeine-exposed mice in both a dose-dependent and a time-dependent manner. In terms of physiological responses, both stimulus responses and locomotor activities were significantly affected by intravenous caffeine exposure. Specifically, the tail pinch response was significantly impaired in half of the mice in the 10 mg/kg and 20 mg/kg groups. Moreover, the rearing count decreased in the 10 mg/kg group at 1.5 to 6 h and in the 20 mg/kg group at 1.5 h after intravenous caffeine exposure. Furthermore, locomotor activity was markedly increased 0.25 h after intravenous caffeine administration in the 20 mg/kg group. These findings clearly indicate that intravenous caffeine exposure significantly impacts functional behaviors, as assessed by an FOB test, which is consistent with widely accepted safety pharmacology testing guidelines.