Sex differences in auditory brainstem response audiograms from vasopressin-deficient Brattleboro and wild-type Long-Evans rats.

Payton E Charlton,Micheal L Dent,Kelcie C Schatz,Matthew J Paul,Kali Burke,Paul Hinckley Delano

doi:10.1371/journal.pone.0222096

Payton E Charlton, Micheal L Dent + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0222096

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Journal: PloS one	Publication Date: Aug 30, 2019
Citations: 5	License type: CC BY 4.0

Affiliation: University at Buffalo, State University of New York

Abstract

Rats are highly social creatures that produce ultrasonic vocalizations (USVs) during social interactions. Brattleboro rats, a Long-Evans derived rat that lacks vasopressin (AVP) due to a mutation in the Avp gene, exhibit atypical social behavior, including fewer USVs with altered spectrotemporal characteristics during social interactions. It is unclear why Brattleboro rats produce atypical USVs, but one factor could be differences in auditory acuity between them and wild-type Long Evans rats with functional vasopressin. Previous studies have suggested a link between increased levels of AVP and auditory processing. Additionally, few studies have investigated sex differences in auditory perception by Long-Evans rats. Sex differences in auditory acuity have been found throughout the animal kingdom, but have not yet been demonstrated in rat audiograms. This study aimed to measure auditory brainstem response (ABR) derived audiograms for frequencies ranging from 1 to 64 kHz in male and female homozygous Brattleboro (Hom), heterozygous Brattleboro (Het), and wild-type (WT) Long-Evans rats to better understand the role of AVP and sex differences in auditory processing by these rats. We failed to detect significant differences between the ABR audiograms of Hom, Het, and WT Long-Evans rats, suggesting that varying levels of AVP do not affect auditory processing. Interestingly, males and females of all genotypes did differ in their ABR thresholds, with males exhibiting higher thresholds than females. The sex differences in auditory acuity were significant at the lowest and highest frequencies, possibly affecting the perception of USVs. These are the first known sex differences in rat audiograms.

Highlights

Vocal communication is thought to serve a key role in facilitating or suppressing different behaviors, such as approach behaviors and play
Male and female wild-type Long-Evans rats (WT; n = 10; 5 males, 5 females) and those homozygous (Hom; n = 10; 5 males, 5 females) or heterozygous (Het; n = 10; 5 males, 5 females) for the Brattleboro mutation were obtained from our breeding colony maintained at the University at Buffalo, State University of New York, which were derived from rats obtained from the Rat Resource and Research Center (University of Missouri, Columbia, MO)
While this study reveals that the basic auditory processing of pure tones and clicks by anesthetized homozygous Brattleboro (Hom), Het, and WT LongEvans rats is equivalent, future studies should measure the perception of more tones in the ultrasonic range, as well as ultrasonic vocalizations (USVs), across more ages

Summary

Objectives

This study aimed to measure auditory brainstem response (ABR) derived audiograms for frequencies ranging from 1 to 64 kHz in male and female homozygous Brattleboro (Hom), heterozygous Brattleboro (Het), and wildtype (WT) Long-Evans rats to better understand the role of AVP and sex differences in auditory processing by these rats.

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