Oxytocin-Induced Emetic Responses in Shrews

Shrews were habituated to IP injections and to clear plastic observation chambers (23.5 × 15.25 × 17.8 cm) for two consecutive days prior to experimentation. Two hours before dark-onset, the animals were injected IP with native OT (50 μg/kg, 100 μg/kg, 500 μg/kg, 5mg/kg or 0.05, 0.1, 0.5, and 5 μmol/kg respectively), OT-B₁₂ (143 μg/kg, 286 μg/kg, 1.4 mg/kg, 14.3 mg/kg or 0.05, 0.1, 0.5, and 5 μmol/kg respectively) or saline, then video-recorded (Vixia HF-R62, Canon) for 120 minutes. After 120 min, the animals were returned to their cages. Treatments were separated by 3 days. Analysis of emetic episodes were measured by an observer blinded to treatment groups. Emetic episodes were characterized by strong rhythmic abdominal contractions associated with either oral expulsion from the gastrointestinal tract (i.e., vomiting) or without explusion of materials (i.e., retching). Latency to the first emetic episode, total number of emetic episodes and number of emetic episodes per minute were quantified as previously described ^{21 ,22 ,32 (link)}.