Rise in thymocyte number and thymulin serum level induced by noise

A high level of noise is known to induce important changes in the immune system. In this work, the effect of sound stress on the circulating level of thymulin and on the cellularity of the thymus gland was studied. The experiments were done in RK mice exposed to a noise level of 100 dB for a period of 1 h. Following the noise exposure, the animals were bled at different times for thymulin titration, or killed in order to evaluate the number of cells and the weight of each thymus. The results indicate that young mice exposed to the stressor stimulus show an increase in serum thymulin titre, and at the same time they show an increment in thymus weight and in thymocyte number compared to control. These results support a new argument in favour of the theory of a central nervous system control on the thymus function.