[Postnatal development of brainstem auditory evoked potential and middle latency response in rats].

AIM

To compare the postnatal development of brainstem auditory evoked potential (BAEP) with that of middle latency response (MLR) in rats.

METHODS

The postnatal development of BAEP and MLR had been studied continuously for 10 weeks in the same groups of rat Pups.

RESULTS

BAEP and MLR emerged at day 14 and 17 respectively. The peak latencies of BAEP's waves shortened systematically with age, especially during 3-4 weeks. The peak latency of wave I reached adult value at day 29, and the peak latencies of the rest waves reached adult ones at day 70. However, the peak latencies of wave Po and Na in the first time evoked MLR had already been at adult values. Though the peak latencies of wave Pa, Nb and Pb also shortened with age, they reached adult ones quickly at day 20-23. The wave amplitudes of BAEP's wave I ,III, IV and MLR's wave Nb, Pb increased quickly with age during 3-4 weeks. Their peak values were much bigger than adult ones and then decreased gradually.

CONCLUSION

The postnatal development of BAEP and MLR proceeded in a similar way in rats, but the peak latencies of MLR reached adult values much earlier than that of BAEP.