ABER latencies are prolonged in rat pups fed a biotin deficient diet

Abstract

The effects of biotin deprivation on ABER were studied in rat pups fed a diet that lacked this compound. Pregnant rats were either fed a normal rat diet (controls) or a special diet without biotin (Teklad, Harlan Sprague Dawley, Madison, WI). After weaning, the respective diets were continued in pups from each group. ABER was tested under chloral hydrate anesthesia (380 mg/kg) using clicks (100 μs, 5/s) and tone bursts (3‐ms duration, 1.5‐ms rise‐fall time at 2, 8, 16, and 32 kHz) presented free field with a driver suspended 8 cm above the vertex in the median plane. Responses were obtained using an active lead from the vertex with a reference electrode in the nose. Blood levels of biotin were measured using a microbiological assay. Animals on the biotin‐free diet showed alopecia and dry, scaly skin. There was no significant difference in ABER threshold in control versus experimental animals. However, there was a significantly longer brain‐stem transmission time (interpeak latencies from waves I to IV) in biotin‐deficient animals. The lowering of serum biotin in experimentals was confirmed by microbiologic assay. These findings suggest that biotin deficiency in the developing rat adversely affects auditory‐nerve and/or brain‐stem development. These effects could be mediated by a delayed myelination of these structures. [Work supported by Deafness Research Foundation.]