Abstract: ObjectiveTo study the effects of 8Hz,90dB and 130dB infrasound on the weight of SD rats and its possible mechanism.Methods30 male SD rats were randomly divided into the control group, 8Hz-90dB and 8Hz-130dB groups according to their original weights. The experimental groups exposed to infrasound of 8Hz-90dB or 8Hz-130dB 2 hours every day, and the control group was placed in the infrasonic storehouse without infrasound exposure. The experiment lasted for 42 days. All the rats were weighed up every 3 days.Other 75 rats were randomly divided into 7,14,21,28,35 days of control group and 8Hz-90dB and 130dB infrasound groups.Each group was given different parameter of infrasound.Then the stomach and duodenum was taken and given immunohistochemistrical straining for 5-HT(including another 15 rats of the weight group). The content of 5-HT in stomach sinus and duodenum was detected under an optical microscope.ResultsThe weight of rats exposed to infrasound increased slower than that of the control(P=0.000);a magnificent difference was observed between 90dB and 130dB group(P=0.000).Rats exposed to 130dB infrasound gained less weights than that exposed to 90dB. The infrasound group expressed more 5-HT in stomach sinus and duodenum,and the peaks were at the 28th day of 8Hz-130dB group and the 35th day of 8Hz-90dB group(P<0.01).ConclusionInfrasound of 8Hz-90dB and 8Hz-130dB can restrain the increase of weight of rats, which possibly related to the increase of 5-HT in stomach and duodenum.

Key words: infrasound, rats, weight, stomach, duodenum, 5-hydroxy-tryptamine(5-HT)