Stress Reaction to Intense Sound Exposure Under Different Arousal Levels in Guinea Pigs

Abstract

The general impact of high intensity sound exposure on 25 guinea pigs was investigated at three different levels of arousal: 10 during general anaesthesia. 10 during partial arousal, and 5 during complete arousal. Parameters recorded before and during noise exposure were mean arterial blood pressure, pulse rate, and plasma norepinephrine levels. The anaesthetized group showed no increase in the three parameters during sound exposure. Under partial arousal, pulse rate and norepinephrine level increased significantly: pulse rate from 224.5 beats/min before exposure to 278.6 beats/min during exposure, and norepinephrine level from 558 pg/ml before sound exposure to 1276 pg/ml during exposure. At the time of the complete arousal state norepinephrine and pulse rates increased significantly during noise exposure, while blood pressure showed no additional increase as a result of sound exposure.

Evidence for a dynorphin-mediated inner ear immune/inflammatory response and glutamate-induced neural excitotoxicity: an updated analysis

“…Furthermore, the participation of inner ear DYNs has not been investigated in studies of 1) stress-induced excitotoxicity, 2) immune/inflammatory responses, and 3) stress-induced changes in auditory thresholds. Nevertheless, in animal investigations, exposure to restraint stress or to AOS often leads to a significant rise in both plasma norepinephrine (NE) (Muchnik et al 1998) and plasma corticosterone ) levels that correlate with changes in peripheral auditory sensitivity (Canlon et al 2007;Muchnik et al 1980). Such auditory changes often include a lowering of auditory thresholds (Muchnik et al 1992).…”