Progesterone affects hearing
If postmenopausal women take progesterone as part of hormone replacement therapy, their hearing could deteriorate. This is the result of comparing the effects of estrogen alone with a combination of estrogen and progesterone.
Patricia Guimaraes from the University of Rochester and her colleagues measured the hearing ability of 124 women between the ages of 60 and 86 using various methods. In all cases, women who took a combination of progesterone and estrogen performed worse. The values for women who only took estrogen and the members of the control group, however, did not differ significantly: Both hearing loss decreased equally, although not to the same extent as with progesterone. The researchers thus disproved a protective effect of estrogen on the sense of hearing, as had been suspected in other studies.
The scientists suspect that the different effects of the two hormones on GABA receptors in the brain are responsible for the impairment. While estrogens increase the excitability of the associated nerve cells through various processes, progesterone has the opposite effect. In another study, researchers observed, among other things, lower GABA concentrations and also reduced release of the neurotransmitter and reduced binding to the receptors in age-related hearing loss.