Acute exposure to noise affects sodium-dependent high-affinity choline uptake in the central nervous system of the rat.

Rats were acutely (45 min) exposed to white noise at intensity of either 70 or 100 dB. Sodium-dependent high-affinity choline uptake was determined in the striatum, frontal cortex, hypothalamus, and hippocampus immediately after exposure. The effects of noise on choline uptake varied according to the intensity of the noise and the brain area studied. Exposure to noise of 70 dB significantly increased the choline uptake in the frontal cortex, hypothalamus, and hippocampus as compared to the uptake of sham-exposed rats, whereas decreased choline uptake in the frontal cortex and hippocampus was observed acute exposure to noise of 100 dB. No significant effect on choline uptake in the striatum was seen after exposure to noise of either intensity. In addition, pretreatment of the rats with the narcotic antagonist naltrexone (1 mg/kg, IP) before noise exposure blocked the effects of noise on choline uptake in the central nervous system. Changes in cholinergic activity in the central nervous system could be a response to the stress effect of noise and may be mediated by endogenous opioids.