Night noise guidelines for Europe - WHO/Europe - World Health ...

)
148
APPENDICES
50
40
Young rats
Old rats
Fig. 3
Above: Recovery after stress
(young and old rats).
Below: Sapolsky´s
Glucocorticoid
Cascade Model
30
20
10
0
Rest immobilization
Recovery
stress
0 1 4h
Time
STRESS
DOWN - REGULATION
NEURONAL LOSS
CORTICOSTERONE
HYPERSECRETION
NEGATIVE FEEDBACK
RECEPTOR
LOSS
INSENSITIVITY
CONCOMITANTS OF
HYPERADRENOCORTICISM
Immunosuppression
Muscle Atrophy
Osteoporosis/Hypercalcemia
Hyperglycemia/Hyperlipidemia
Arteriosclerosis
Steroid diabetes
Therefore, acute stress leads, in old animals, to considerably prolonged cortisol
increases. On the other hand, chronically repeated stress activates the HPA axis and
can cause cortisol receptor losses even in younger animals, a process generally developing
only in old age. Finally, chronic cortisol hypersecretion may occur along with
follow-up health defects.
Aguas et al. (1999) exposed a special breed of mice to the above described model of
occupational low frequency noise for three months. Chronic low frequency noise
exposure accelerated the expression of the autoimmune disease and was associated
with kidney lesions and increased mortality.
Chronic noise exposure of animals on a suboptimal Mg diet led to increases of connective
tissue and calcium and decreases of Mg in the myocardium (Günther, Ising
and Merker, 1978). These changes were correlated with noradrenaline changes. Since
they are also correlated with normal ageing, the noise stress induced changes may be
interpreted as accelerated ageing (Ising, Nawroth and Günther, 1981). Even the lifespan
was reduced in rats on an Mg deficient diet, and was further dose-dependently
reduced in combination with noise exposure (see Table 1).
NIGHT NOISE GUIDELINES FOR EUROPE