Antagonistic Effects of Tetramethylpyrazine on Hypoxic Respiratory Depression in Rats

OBJECTIVE: Tetramethylpyrazine (TMP) is an alkaloid extracted from the root and stem of the traditional Chinese herbal medicine called Chuanxiong. The present study aims to study the effects of TMP on hypoxic respiratory depression in rats. Materials and methods. The effects of TMP on respiratory responses of rats induced by hypoxia were observed by diaphragm electromyogram (EMG) recording. The effects of TMP on the protein expression of FOS and acid sensing ion channel(1a) (ASIC(1a)) in the brainstem induced by hypoxia were investigated by immunohistochemistry. RESULTS: The respiration of rats was first excited and then depressed during hypoxia treatment, while TMP pretreatment could significantly antagonize the respiratory depression induced by hypoxia (P < 0.01). Hypoxia obviously induced the protein expression of FOS (P < 0.01) and ASIC(1a)(P < 0.05) in the brainstem, which can be also significantly inhibited by TMP pretreatment. CONCLUSIONS: TMP has protective effects on hypoxic respiratory depression, and the mechanisms might be concerned with its downregulation of FOS and ASIC(1a) in the brainstem induced by hypoxia.