Loss ofEsr1Does Not Affect Hearing and Balance

Abstract

AbstractAlthough estrogen affects the structure and function of the nervous system and brain and has a number of effects on cognition, its roles in the auditory and vestibular systems remain unclear. The actions of estrogen are mediated predominately through two classical nuclear estrogen receptors, estrogen receptor 1 (ESR1) and estrogen receptor 2 (ESR2). In the current study, we investigated the roles of ESR1 in normal auditory function and balance performance using 3-month-old wild-type (WT) andEsr1knockout (KO) mice on a CBA/CaJ background, a normal-hearing strain. As expected, body weight ofEsr1KO females was lower than that ofEsr1KO males. Body weight ofEsr1KO females was higher than that of WT females, while there was no difference in body weight between WT andEsr1KO males. Similarly, head diameter was higher inEsr1KO vs. WT females. Contrary to our expectations, there were no differences in auditory brainstem response (ABR) thresholds, ABR waves I-V amplitudes and ABR waves I-V latencies at 8, 16, 32, and 48 kHz, distortion product otoacoustic emission (DPOAE) thresholds and amplitudes at 8, 16, and 32 kHz, and rotarod balance performance (latency to fall) between WT andEsr1KO mice. Furthermore, there were no sex differences in ABRs, DPOAEs, and rotarod balance performance inEsr1KO mice. Taken together, our findings show thatEsr1deficiency does not affect auditory function or balance performance in normal hearing mice, and suggest that loss ofEsr1is likely compensated by ESR2 or other estrogen receptors to maintain the structure and function of the auditory and vestibular systems under normal physiological conditions.HighlightsHead diameter of femaleEsr1KO mice was higher than that of female WT mice.ABRs and DPOAEs were not different in WT andEsr1KO mice.There were no sex differences in ABRs and DPOAEs inEsr1KO mice.Rotarod balance performance was not different in WT andEsr1KO mice.There were no sex differences in rotarod balance performance inEsr1KO mice.Loss ofEsr1does not affect auditory function or balance performance under normal physiological conditions.