Role of calcium in the analgesic action of tetrahydroisoxazolepyridinol and muscimol

Abstract

The role of calcium in the analgesic activity of 4,5,6,7-tetrahydroisoxazole-(5,4-c) pyridin-2-ol (THIP) and muscimol has been investigated using the acetic acid assay procedure. THIP and muscimol produced significant analgesic response. Whilst neither calcium chloride nor nifedipine in the doses employed significantly altered the number of writhings, calcium chloride antagonized the analgesic responses of THIP and muscimol while nifedipine potentiated them. Similar responses were recorded for morphine. These findings suggest that THIP and muscimol, like morphine, might alter the calcium movements across the plasma membrane to elicit the analgesic response.