The response of microglia in the hypothalamic paraventricular nucleus of rats to infrasound

Objective To evaluate the effects of infrasound on paraventricular nucleus of hypothalamus microglia, astrocytes and the relationship between them in rats.Methods The rats were divided into four groups according to time of infrasound exposure: infrasound exposure 1 d, infrasound exposure 7 d, infrasound exposure 14 d and the control group. Rats were exposed to infrasound for 2 h every day with a main frequency of 16 Hz and a sound pressure level of 130 dB.Results The results showed that complement receptor 3(OX42)-positive cells and glial fibrillary acidic protein (GFAP)-positive cells were rare in control group. The amplitude of OX42-positive cells significantly increased at once when rats were exposed to 16 Hz 130 dB infrasound, and then decreased after 7 days. But GFAP-positive cells were increased on the 7 th day and peaked on the 14 th day. There was close relationship between the changes in microglia and astrocytes.Conclusion Microglia is activated earlier than astrocytes after exposure to infrasound. The changes of microglia and astrocytes are closely related.