Tail immersion test is a specific central procedure.This test has shown that mu (μ) opioids receptors were involved in antinociceptive effect rather than kappa (k) or delta receptors [39]. Literature shows that descending inhibition pathways and opioidergic system involving serotonergic and noradrenergic systems play a vital role in pain regulation at spinal and supraspinal level [40,41].The METS has significantly increased the latency time(%) at a dose of 150 mg/kg. Maximum effect for all test doses of METS was recorded after 60 min which persists upto 120 min. Naloxone an opioid receptor antagonist, when applied reversed profoundly the analgesic effect of METS after 30 min of administration. This shows that the antinociceptive potential of the extract is due to activation of the opioid receptors.