Antinociceptive Effects of VBME in Mice

BALB/c mice of either sex (n = 6) weighing 18–22g were acclimatized to laboratory conditions one hour before the start of experiment with food and water available ad libitum. Animals were then subjected to pre-testing on hot plat (Havard apparatus) maintained at 55 ± 0.1°C. Animals having latency time greater than 15 s on hot plate during pre-testing were rejected (latency time) [12 ]. All the animals were divided in eight groups each of six mice. Group I was treated with saline (10ml/kg), group II was treated with Tramadol^R (30mg/kg i.p). Group III, IV and V were treated with 100, 200 and 300mg/kg VBME, i.p. respectively. After 30min of treatment the animals were placed on hot plat and the latency time (time for which mouse remains on the hot plate (55 ± 0.1°C) without licking or flicking of hind limb or jumping) was measured in seconds. In order to prevent the tissue damage a cut-off time of 30 s were imposed for all animals. To find out the opiodergic mechanism in the analgesic activity of VBME, Groups VI and VII were treated with naloxone (0.5mg/kg s.c.) and after 10min these groups were treated with VBME (200 and 300mg/kg, i.p), while group VIII was treated with Tramadol^R (30mg/kg i.p.) after 10min of naloxone injection. The latency time for all groups was recorded at 0, 30, 60, 90 and 120min. Percent analgesia was calculated using the following formula:
% Analgesia = (Test latency – control latency)/(Cut – off time – control latency) × 100