Alterations in cochlear function during induced acute hyperinsulinemia in an animal model.
Hyperinsulinism secondary to peripheral insulin resistance has been described as the most frequent etiologic factor in cochlear and vestibular syndromes.


OBJECTIVE
This experimental study recorded and analyzed evoked auditory potential changes using transtympanic electrocochleography (EcochG) during induced acute hyperinsulinism in an animal model.


METHODS
Six adult male sheep were randomly divided into 2 groups. The animals were submitted to EcochG under general anesthesia, and a peripheral blood sample was collected to measure glycemia and insulinemia. Animals in the intervention group (n=3) received regular human insulin IV (0.1 U/kg). The control group (n=3) received saline solution. Glycemia and insulinemia were measured simultaneously with the recording of evoked potentials at 10-minute intervals during 90 minutes.


RESULTS
The intervention group experienced a progressive suppression in action potential amplitude when compared to the control group (p=0.001).


CONCLUSIONS
Data strongly suggest that acute induced hyperinsulinism suppresses cochlear function. Results may be attributed to loss of Na+K+ATPase activity in the stria vascularis, leading to loss of endocochlear potential and subsequent depolarization of cochlear hair cells as well as of neural cells in the auditory portion of cranial nerve VIII.
Angeli
Roberto Dihl
RD
Otorhinolaryngology, Universidade Federal do Rio Grande do Sul, UFRGS.
Lavinsky
Luiz
L
Dolganov
Alexandre
A
D000161:Acoustic Stimulation; D000208:Acute Disease; D000818:Animals; D001300:Audiometry, Evoked Response; D003051:Cochlea / Q000503:physiopathology*; D004195:Disease Models, Animal; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006946:Hyperinsulinism / Q000150:complications / Q000503:physiopathology*; D008297:Male; D012756:Sheep