Glucocorticoid influences on the auditory brain-stem responses in man

Area of Science:

• Neuroscience
• Endocrinology
• Auditory System

Background:

• Human auditory brain-stem responses (ABRs) are electrophysiological measures reflecting the integrity of the auditory pathway.
• Glucocorticoids are key hormones involved in the stress response and have widespread effects on the central nervous system.

Purpose of the Study:

• To investigate whether peripheral endocrine signals, specifically plasma glucocorticoid concentration, influence human auditory brain-stem responses (ABRs).
• To determine if hydrocortisone administration affects ABR characteristics in healthy male adults.

Main Methods:

• A double-blind, latin-square within-subject design was employed with 13 healthy male adults.
• Participants received an intravenous infusion of either 50 mg hydrocortisone or a placebo 1 hour prior to testing.
• ABRs were recorded using click stimuli presented at three intensities (80, 60, 40 dB HL) and three rates (39, 10, 5 clicks/sec).
• Oral temperature was monitored throughout the experiment.

Main Results:

• Hydrocortisone significantly reduced the latencies of ABR waves III, V, and VI at low stimulus intensities.
• The glucocorticoid also decreased the latencies of waves V, VI, and VII when stimuli were presented at a slow rate.
• No significant effects were observed at high stimulus intensities or fast stimulus rates.

Conclusions:

• Human auditory brain-stem responses are sensitive to changes in peripheral glucocorticoid levels.
• Hydrocortisone administration can modulate neural transmission speed within the auditory brainstem.
• Further research is required to elucidate the specific neurobiological mechanisms underlying these observed effects.