Effects of Cyclophosphamide Pretreatment on Hearing in Guinea Pigs with Autoimmune Sensorineural Hearing Loss

WANG Yinfeng; WANG Yalin; GAO Wei

doi:10.3969/j.issn.1672-2922.2014.02.36

Abstract：Objective To study the effects of cyclophosphamide in guinea pigs with autoimmune deafness. Methods Guinea pigs were randomly divided into three groups (10 in each). One group of animals received intracutaneous inoculation of an emulsion consisting of equal parts of crude inner ear antigens (CIEAgs, 0.2 ml) and complete Freund’s adjuvant (CFA) at multiple sites two days after pretreatment with cyclophosphamide (Experimental Group). The second group of animals received only inoculation of CIEAgs and CFA (Control Group #1), and the rest animals received only cyclophosphamide pretreatment (Control Group #2). Animals in all three groups received auditory brain-stem response (ABR) testing before and on Days 7, 14 and 21 after immunization. Results The mean ABR threshold across all animals was 29.50±5.56 dB SPL before immunization. After immunization, the threshold was 52.50±12.72 dB SPL, 36.50±11.25 dB SPL and 31.50±3.37 dB SPL on Day 7, 58.50± 14.79 dB SPL, 33.25 ± 8.93 dB SPL and 30.50 ± 3.69 dB SPL on Day 14, and 46.25 ± 12.45 dB SPL, 30.00 ± 4.29 dB SPL and 30.00±3.33 dB SPL on Day 21 or the experimental group, Control Group 1 and Control Group 2, respectively. The ABR thresh-old for the experimental group on all after immunization days was higher than those for the two control groups (P<0.01) and than before immunization (P<0.01). The ABR threshold for Control Group 1 was higher than before immunization on post-im-munization Day 7 only (P<0.05), and the ABR threshold for Control Group 2 showed no significant post-immunization change. Conclusions After pretreatment with cyclophosphamide, single inoculation of CIEAgs-CFA emulsion can significantly in-crease ABR thresholds in guinea pigs.