22-28 KHZ ULTRASONIC VOCALIZATIONS ASSOCIATED WITH DEFENSIVE REACTIONS IN MALE-RATS DO NOT RESULT FROM FEAR OR AVERSION

This study was carried out to determine whether 22-28 kHz vocalization s emitted during intermale interactions in adult rats were related wit h a state of fear, aversion or resulted from painful stimulation. Voca lizations in the 22-28 kHz range were measured in male rats during non -aggressive and aggressive social interactions; when given foot shock with a partner; during nonaggressive social interactions after an inje ction of (i) acetic acid (1%, IP); (ii) pentylenetetrazol (20-30 mg/kg , IP) and (iii) lithium chloride (63.8 mg/kg, IP). Ultrasonic vocaliza tions were consistantly detected in all rats while the animals display ed defensive or submissive postures when tested as intruders confronte d with offensive residents or when administered foot shocks. Only occa sional vocalizations were emitted, even in the presence of a partner, when the animals had received other painful or aversive treatments. Th ese data support the hypothesis that 22-28 kHz vocalizations during in termale interactions are associated with defensive postures and are no t the consequence of a state of fear or aversion.