Study Of Auditory Evoked Potentials And Correlative Factors In Diabetic Rats

Aim: (1) To search sensitive and valuable method in the early diagnosis of diabetic central neuropathy (DCN); (2) to probe into the relationship between nitric oxide (NO) and DCN and (3) to find out the morphological changes of central nervous system in DCN. Methods: Twenty-four adult male SD rats were randomly divided into control group and experimental diabetes (ED) group. The ED group rats were induced to become ED by injection of STZ. Before and at 2,4,6,8 and 10 weeks after STZ injection, the blood glucose, BAEI~, MLR and blood NO were measured in ED group and compared with control group. One rat of each group was sacrificed randomly and its brainstem was taken out to do morphological observation at 6, 8 and 10 weeks after STZ injection. T-test and linear correlate statistics methods were used. Results: The amplitudes of I, III, LV and V of BAEP and Pa, Nb and Pb of MLR of ED group increased after 2 weeks of STZ injection. The peak latency (PL) of I, III, IV and V of BAEP, all the waves of MLR and the interpeak latency (IPL) of I-ILL and Ill-V of BAEP prolonged; all waves amplitudes of BAEP and Pa, Nb and Pb amplitudes of MLR increased after 4 weeks. All PL 3 of BAEP and MLR, all IPL of BAEP and P2-Pb of MLR prolonged; the amplitudes of I, II, III and IV of BAEP and P0, N8 and P0 of MLR increased after 6 weeks. All PL and IPL of BAEP and MLR prolonged; the amplitudes of I, III, IV and V of BAEP and Pa and Pb of MLR increased after 8-10 weeks. The duration of diabetes was positively associated with the PL and LPL of BAEP and PL of N a, Nb and Pb of MLR. The blood glucose was not associated with the PL and IPL of BAEP and MLR. The blood NO increased to the top in ED group at 2 weeks after injection of STZ, and then decreased gradually. There were negative correlations between blood NO and PL and IPL of BAEP, PL of MLR and P0-P8 IPL of MLR. Morphological observation found that there was no difference between ED and control groups at 6 weeks after STZ injection and there were hypoxia denaturation of central nervous system and reducion of neuron in ED group at 8 weeks and 10 weeks. Conclusions: (1) Serial observations on BAEP and MLR gave evidences of early DCN in STZ-induced ED rats. (2) The changes of BAEP and MLR in early ED were observed and became more evidence. This indicated that BAEP and MLR were sensitive and valuable in the early diagnosis of DCN. (3) Amplitude was the earliest change of BAEP and MLR, the significance of it remained to be further researched. (4) Reduction of NO may play a role in the pathogenesis of DCN. (5) Morphological change of DCN is hypoxia denaturation of nervous system.