ScienceDaily (Dec. 15, 2007) — Levels of cholesterol in the membranes of hair cells in the inner ear can affect your hearing, said a consortium of researchers from Baylor College of Medicine, Rice University and Purdue University in a new report in the Journal of Biological Chemistry.

Dr. William Brownell, professor of otolaryngology at BCM and his colleagues, said that the amount of cholesterol in the outer hair cell membrane found in the inner ear can affect hearing.

"We've known for a long time that cholesterol is lower in the outer hair cell membranes than in the other cells of the body," said Brownell, senior author of the report "What we didn't know was the relationship it had to hearing."

Dr. Lavanya Rajagopalan, postdoctoral fellow in otolaryngology at BCM, led the research team that manipulated the cholesterol levels in outer hair cells of mice. She and her colleagues measured the mice's hearing ability by a technique that uses inaudible sound waves emitted from the ear as it reacts to external sound. There are two types of sensory hair cells in the inner ear called the inner and outer hair cells. It is the outer hair cells that are affected by cholesterol levels and produce the inaudible sounds in the ear canal.

"Depleting the cholesterol resulted in a hearing loss. Adding cholesterol initially increased hearing but later resulted in a hearing loss," Brownell said. "So you can change an animals hearing just by adding or subtracting cholesterol."

The fine tuning of the cholesterol happens naturally in development and does not change significantly after birth. In contrast, cholesterol in the bloodstream can vary with eating habits. That is why avoiding fatty foods can promote a healthy heart.

"Will our hearing be affected if we continually eat greasy meals? Right now, we don't see a connection between the two," Brownell said. "The results of the study help us understand the cellular mechanisms for regulating hearing and give us another way to potentially help those with hearing loss."

Others who took part in the study include Drs. Anping Xia, Angela Sturm, John S. Oghalai, Fred A. Pereira, and research assistant Haiying Liu of BCM, Jennifer N. Greeson and Dr. Robert M. Raphael of Rice University and Dr. Amy L. Davidson of Purdue University.

This study was supported by grants from the National Institute of Deafness and Other Communication Disorders, the National Science Foundation, the Deafness Research Foundation, the Keck Center for Interdisciplinary Bioscience Training and the Welch Foundation.

Related Stories

Understanding How We Hear (Feb. 17, 2005) — A new understanding of how we can hear such a wide range of sounds is reported in the online issue of Nature. The study, by researchers at the universities of Bristol, Wisconsin and Cambridge, ...  > read more

Type Of Supporting Cells Resistant To Notch Signaling Discovered (Jan. 25, 2009) — Researchers have shown that by blocking a biochemical pathway called the Notch signaling pathway, most of the supporting cells in the inner ear of juvenile mice are induced to directly change into ...  > read more

Genes In Human Inner Ear Cells Restored (June 14, 2007) — Researchers have discovered a way to transfer genes, which they hope will restore hearing, into diseased tissue of the human inner ear. This important step brings scientists closer to curing genetic ...  > read more

New Cell Culturing Method Pumps Up The Volume (Sep. 27, 2007) — In a breakthrough that will likely accelerate research aimed at cures for hearing loss, tinnitus and balance problems, scientists have perfected a laboratory culturing technique that provides a ...  > read more

Treatment For Hearing Loss? Scientists Grow Hair Cells Involved in Hearing (Aug. 30, 2008) — Scientists have successfully produced functional auditory hair cells in the cochlea of the mouse inner ear. The breakthrough suggests that a new therapy may be developed in the future to successfully ...  > read more

Search ScienceDaily

MP3 Players: How Loud Is Too Loud?