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Acute hypoxia blunts cold sensitivity through the inhibition of the lateral parabrachial nucleus in rats

WANG Ze-Jun^1,2,3, YANG Tian^1,2,3, HUANG Qing-Yuan^1,2,3,*

¹Department of Cold Environmental Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing 400038, China；²Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China；³Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China

Abstract

To explore the changes of cold sensitivity after exposure to acute hypoxia and its mechanisms, Sprague-Dawley rats were divided into normoxia control group (21% O2, 25 °C), 10% O2 hypoxia group (10% O2, 25 °C), 7% O2 hypoxia group (7% O2, 25 °C), normoxia cold group (21% O2, 10 °C) and hypoxia cold group (7% O2, 10 °C). Cold foot withdrawal latency and preference temperature of each group were measured, skin temperatures were estimated using an infrared thermographic imaging camera, body core temperature was recorded by wireless telemetry system, immunohistochemical staining was used to detect the expression of c-Fos in the lateral parabrachial nucleus (LPB). The results showed that acute hypoxia significantly prolonged the latency of cold foot withdrawal and significantly enhanced the intensity of cold stimulation for foot withdrawal, and the rats under hypoxia preferred cold temperature. Cold exposure (10 °C) for 1 h significantly enhanced the expression of c-Fos in LPB of rats in normoxia, while hypoxia inhibited cold-induced c-Fos expression. Acute hypoxia significantly increased the skin temperature of feet and tails, decreased the skin temperature of interscapular region, and decreased the body core temperature of rats. These results indicate that acute hypoxia can significantly blunt cold sensitivity through the inhibition of LPB, suggesting actively keeping warm measures should be taken at the early stage after ascent to high altitude to prevent the upper respiratory infection and acute mountain sickness.

Key words: Hypoxia; cold; cold sensitivity; body temperature; lateral parabrachial nucleus

Received: 　　Accepted:

Corresponding author: 黄庆愿　　E-mail: huangqingyuan@tmmu.edu.cn

Citing This Article：

WANG Ze-Jun, YANG Tian, HUANG Qing-Yuan. Acute hypoxia blunts cold sensitivity through the inhibition of the lateral parabrachial nucleus in rats. Acta Physiol Sin 2023; 75 (3): 351-359 (in Chinese with English abstract).