Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Auditory acuity in adrenocorticoid insufficiency.

M T Weigel1, G Prazma, H C Pillsbury

  • 1Division of Otolaryngology, Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill 27514.

The American Journal of Otology
|July 1, 1989
PubMed
Summary

This study investigated how the lack of adrenal hormones affects hearing sensitivity and nerve signal transmission in rats. While previous human research suggested that hormone deficiency might increase hearing sensitivity, this experiment found that removing adrenal glands did not change hearing thresholds in rats. However, the researchers observed that the speed of nerve signal transmission from the ear to the brain was slowed down after hormone removal.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Surgical impact of new treatments in breast cancer.

Minerva ginecologica·2013
Same author

Enhanced expression of the PDGFR/Abl signaling pathway in aromatase inhibitor-resistant breast cancer.

Annals of oncology : official journal of the European Society for Medical Oncology·2012
Same author

An in vitro model showing adaptation to long-term oestrogen deprivation highlights the clinical potential for targeting kinase pathways in combination with aromatase inhibition.

Steroids·2011
Same author

Chemoradiation for locally advanced squamous cell carcinoma of the head and neck for organ preservation and palliation.

Archives of otolaryngology--head & neck surgery·2001
Same author

Transient inflammation and dysfunction of the eustachian tube secondary to multiple exposures of simulated gastroesophageal refluxant.

The Annals of otology, rhinology, and laryngology·2001
Same author

Late-phase allergy and eustachian tube dysfunction.

Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery·2001

Area of Science:

  • Endocrinology and auditory acuity research within sensory physiology
  • Neurobiology of steroid hormone signaling pathways

Background:

No prior work had resolved whether adrenal hormone loss directly alters hearing sensitivity in animal models. It was already known that human subjects with adrenal insufficiency often report heightened sound detection capabilities. This discrepancy between clinical observations and experimental evidence remained a persistent challenge for researchers. That uncertainty drove the need for controlled investigations into the physiological basis of these sensory changes. Prior research has shown that glucocorticoids exert significant influence over the metabolic processes within neural tissues. This gap motivated a closer look at how steroid depletion might affect the electrical activity of the auditory system. Scientists previously hypothesized that such hormonal states could lead to increased excitability within the central nervous system. This study seeks to clarify the relationship between steroid availability and the functional integrity of auditory pathways.

Purpose Of The Study:

The aim of this investigation was to examine the hypothesis that glucocorticoid deficiencies lead to decreased auditory thresholds and interference in central impulse conduction. The researchers sought to determine if the previously reported hyperacuity in human subjects could be replicated in a controlled animal model. They specifically wanted to isolate the effects of carbohydrate-active steroid loss on the excitability of neural tissues. The study addressed the uncertainty regarding whether these hormonal changes directly improve sound detection or if they disrupt the processing of auditory signals. By employing a rat model, the team intended to clarify the mechanism behind the state of increased neural excitability. The project was motivated by the need to reconcile clinical observations with physiological evidence from experimental subjects. The investigators focused on measuring both threshold levels and signal latency to provide a comprehensive view of auditory function. This work serves to advance the understanding of how endocrine status influences the efficiency of the central nervous system.

Keywords:
adrenalectomyneural transmissionglucocorticoid deficiencyauditory brain-stem response

Frequently Asked Questions

The researchers observed that adrenalectomy resulted in impaired central neural transmission speed for first and second order neurons, despite finding no significant changes in the actual sound detection thresholds of the experimental animals.

The study utilized electrocochleographic and auditory brain-stem evoked response measurements to assess both the sensitivity of the ear and the latency of signal transmission through the auditory pathways.

The researchers performed adrenalectomies on eight rats to create a state of glucocorticoid deficiency, which was necessary to isolate the specific effects of these hormones on neural excitability.

The team relied on latency measurements to track the timing of neural impulses, which served as the primary data type for identifying deficits in central transmission speed.

Related Experiment Videos

Main Methods:

Review Approach involved a controlled longitudinal study using a rat model to assess the physiological impact of hormone depletion. The researchers performed baseline electrocochleographic and auditory brain-stem evoked response testing on all subjects before any surgical intervention. Following these initial assessments, the team conducted adrenalectomies on the entire group of eight experimental animals. The study design required postoperative monitoring at three distinct intervals to capture the progression of physiological changes. Specifically, the investigators recorded data at three, seven, and twenty-one days after the surgical removal of the glands. This systematic approach allowed for the evaluation of both threshold levels and signal latency across the specified time frame. The investigators compared pre-operative and post-operative data to determine the specific effects of glucocorticoid cessation. This methodology ensured a rigorous assessment of neural excitability and transmission integrity within the auditory pathway.

Main Results:

Key Findings From the Literature indicate that the removal of glucocorticoid-producing glands did not result in any statistically significant changes to the auditory detection thresholds of the rats. The researchers observed that the sound sensitivity remained stable throughout the entire twenty-one day observation period. However, the latency measurements revealed a clear impairment in the transmission speed of the first and second order neurons. This delay in signal conduction suggests that the central neural pathways are negatively affected by the absence of these specific steroids. The data showed that while the ear could still detect sounds at the same volume, the brain received these signals more slowly. These results contrast with earlier human studies that reported improved detection levels in similar hormonal states. The findings demonstrate that the primary effect of the deficiency is on the timing of neural impulses rather than the sensitivity of the auditory system. The study provides evidence that central neural transmission is particularly vulnerable to the loss of carbohydrate-active steroids.

Conclusions:

Synthesis and Implications suggest that the absence of glucocorticoids does not necessarily lead to improved hearing sensitivity in all mammalian models. The authors propose that the observed changes in neural conduction speed indicate a disruption in signal processing rather than a simple increase in excitability. These findings highlight the complex role of steroid hormones in maintaining the efficiency of auditory brain-stem pathways. The researchers emphasize that the lack of threshold shifts in their subjects contradicts earlier human clinical reports. They suggest that the impairment of first and second order neurons points toward a specific vulnerability of central transmission. The study provides a framework for understanding how metabolic shifts influence the timing of neural impulses. Future inquiries might explore the specific molecular pathways linking glucocorticoid receptors to the speed of signal propagation. The authors conclude that further investigation is required to reconcile these findings with existing clinical data regarding auditory hyperacuity.

The authors measured the auditory brain-stem evoked response at three, seven, and twenty-one days post-surgery to track the progression of neural changes over time.

The authors propose that the observed neural transmission delays suggest that glucocorticoids are vital for maintaining the speed of signal conduction, rather than simply modulating the sensitivity of the auditory threshold.