The Research Of Effect Of 17β-estadiol To The Abnormal P50 Auditory Evoked Potential Of Substantia Nigra Induced By 6-hydroxydopamine In Rats

Objective To observe the influence of 6-hydroxydopamine and gonadic estrogen on P50 auditory evoked potential of substantia nigra in rats ;Furthermore, to investigate the effects and possible mechanism of estrogen to the abnormal P50 induced by 6-hydroxydopamine. Methods 137 health adult female Sprague-Dawley rats were randomly divied into nine groups: 1. normal control group(INT-N group); 2. 6-hydroxydopamine Parkinson' s disease model group(INT-6-OHDA group); 3. ascorbic acid solution control group(INT-VITc group); 4. ovariectomy control group(OVX-N group); 5. ovariectomy + 6-hydroxydopamine Parkinson' s disease model group(OVX-6-OHDA group); 6. ovariectoray + estrogen replacement group(OVX-E2-N group); 7. ovariectomy + estrogen replacement + 6-hydroxydopamine Parkinson' s disease model group(OVX-E2-6-OHDA group); 8. ovariectomy + olive oil solution control group (OVX-OIL-N group); 9. sham control group (Sham-N group). P50 auditory evoked potentials of substantia nigra were recorded in different situations by means of stimulation model of conditioning and testing. A comparative study of P50 between groups were performed. Results (1) following behavioral testing : Three groups(6-hydroxydoparaine Parkinson' s disease model group, ovariectomy + 6-hydroxydopamine Parkinson' s disease model group, ovariectomy + estrogen replacement + 6-hydroxydopamine Parkinson' s disease model group) were identified tobe successful Parkinson''s disease models by means of apomorphine-induced rotations; (2) The testing/conditioning(T/C) ratio of P50 is decreased significantly in 6-hydroxydopamine Parkinson' s disease model group as compared to normal, control group(P<0. 01); (3) The T/C ratio of P50 is decreased significantly in ovariectomy contrl group as compared to normal control group (P<0. 01); (4) The T/C ratio of P50 is decreased significantly in ovariectomy + 6-hydroxydopamine Parkinson' s disease model group as compared to 6-hydroxydopamine Parkinson' s disease model group(P<0. 01); (5) The T/C ratio of P50 is increased in ovariectomy + estrogen replacement + 6-hydr-oxydopamine Parkinson' s disease model group as compared to ovariectomy + 6-hydroxydopamine Parkinson' s disease model group(P<0.01). Conclusions 6-hydroxydopamine can give rise to abnormal P50 auditory evoked potential of substantia nigra in normal, ovariectomy and ovariectomy + estrogen replacement female rats; Ovariectomy can result in abnormal P50 auditory evoked potential of substantia nigra in rats; Gonadic estrogen replacement can make the abnormal P50 auditory evoked potential of substantia nigra to noraml level.