Pituitary Adrenocortical Response to Noise Exposure in Rats

Abstract

Male rats were exposed to the wide octave-band noise for eight hours at the intensity of 60, 80, or 100dB (C), respectively. The 11-OHCS concentration in the adrenal glands increased in the initial stage of noise exposure, and returned to the control level soon after. The circadian rhythm of 11-OHCS remained in spite of the continuation of noise exposure except in the initial response. After the noise exposure, rats were exposed again at 100dB (C). The 11-OHCS did not increase in the rats exposed previously at 100dB (C). In all the intensities, the 11-OHCS increased to the control level by ACTH administration at the end of noise exposure. By histamine administration at the end of noise exposure, the increase of the 11-OHCS was less in the rats exposed to 100dB (C) than in the rats exposed to low intensities.