بررسي اثر تزريق داخل بطن مغزي موسيمول و پيكروتوسين بر شدت درد در طي سيكل استروس

Effect of intracerebro-venticular injection of muscimol and picrotoxin on pain sensitivity during estrous cycle

Both baseline pain sensitivity and the response to antinociceptive treatment are influenced by an animalʹs sex and estrous cycle stages. On the other hand, the role of GABA due to GABA.. in nociception was investigated. So the aim of present study was to investigate the effect of ICY injection of a GABA" receptor agonist (muscimol), and an antagonist (picrotoxin) on pain sensitivity during all phases of estrous cycle. Adult female rats weighting 200-250g were used. Rats were maintained on 12h reversed light/dark cycle, and standard temperature 18-22. Food and water were available ad libitum. Pain sensitivity was evaluated by formalin test. This was performed by subcutaneous injection of 50!l1 formalin solution (2.5%) into the hind paw in all phases of estrous cycle. The animals were divided in 6 groups: 1- control, 2- sham, 3- experiment 1 (received 2!l1 ofmuscimol250 and 500!lgirat). 4- experiment 2 (received 2!l1 of picrotoxin 20 and 30!lg/rat). Our data showed that museimol significantly (p<0.05) decrease pain sensitivity in all phases of estrous cycle, but this analgesic effect was higher during proestrusc and estrus than rnetestruse and diestruse, Picrotoxin significantly (p