Ontogenia das vocalizações ultrassônicas em um modelo de autismo

Abstract

Rats are altricial mammals that are born with incomplete development of the nervous system. Thus, during the first three weeks of postnatal life, rapid neuronal maturation is observed, accompanied by significant behavioral changes. During these three weeks, the puppy-mother communication takes place through physical contact, odor, and the emission of ultrasonic vocalizations (USV) from the neonates. These neonatal USVs (average frequency of 40 kHz and duration between 20-160 ms) are emitted in situations of maternal isolation and have characteristics that change throughout development. Thus, the study of ultrasonic emissions is an important tool for understanding the changes in social communication present in neurodevelopmental disorders, such as autism spectrum disorder. In the VPA model of autism, little is known about the postnatal developmental profile of ultrasonic voice production. Therefore, this work aimed to investigate the bioacoustic characteristics of USVs emitted in isolation by control animals and animals exposed to valproic acid (VPA) at postnatal ages 11, 14, and 18. Our results show that VPA animals have less weight gain during the postnatal period compared to controls, but they did not show differences in the age of opening of the external acoustic meatus or eyes. Regarding vocalizations, the VPA animals vocalized for less time and presented shorter vocalizations than the control animals at the age of P11 and P14. At age P14, the VPA animals presented USVs with greater amplitude between maximum and minimum frequency, greater sinuosity, higher maximum frequency, and higher onset frequency. These findings, when compared by age, suggest that VPA animals show early maturation of the bioacoustic characteristics of ultrasonic vocalizations.