17 After all tests, rats were given a lethal administration of ether. The microinjection site was marked by injection of Cresyl Violet (0.2 l) into the hippocampus. The brain was removed, placed in formalin (10%). Coronal section

was prepared to determine the accuracy of the surgery. The data of animals, in which that cannulation was not correct, Inhibitors,research,lifescience,medical were removed. Data Analysis Number of rats was determined according to a pilot study using the following formula: n=[(Zα+Zβ)SD/mean difference]×2 using Zα=1.96, Zβ=0.84, SD=0.06, and mean difference of 0.07 yielded a sample size of 4.62 for each group, therefore a sample of five rats were included in each group. Data, presented as mean±SD, were analyzed by Statistical Package for Social Sciences (SPSS, version 18). They were analyzed separately

for each group with Kruskal-Wallis nonparametric test. In case of significant Inhibitors,research,lifescience,medical results with Kruskal-Wallis test, pairwise comparisons were made using Tukey test. A P value of ≤0.05 was considered statistically significant. Results The Effects of Muscimol Intrahippocampal injection of muscimol (250 µg/rat) significantly decreased the level of pain in phase 1 of formalin test during proestrus (P=0.008) and estrus (P=0.000) stages of ABT-199 research buy estrous cycle (figure 1). Intrahippocampal Inhibitors,research,lifescience,medical injection of muscimol (250 and 500 µg/rat) significantly decreased the level of pain in phase 1 of formalin test during metestrus (P=0.000) and diestrus (P=0.000) stages of estrous cycle (figure 1). Intrahippocampal injection of muscimol (250 and 500 µg/rat) significantly decreased the level of

pain in phase 2 of formalin test during proestrus (P=0.000), Inhibitors,research,lifescience,medical estrus (P=0.004) and metestrus (P=0.000) stages of estrous cycle, whereas no significant change in the level of pain was observed during diestrus stage of estrous cycle (figure 1). The analgesic effect of muscimol was significantly (P=0.004) higher during proestrus and estrus than during metestrus and diestrus stages of estrous cycle (figure 1). Figure 1 Effects of muscimol on pain score in formalin Inhibitors,research,lifescience,medical test during different stages of estrous cycle in the rat. The Effects of Picrotoxin Intrahippocampal injection of picrotoxin (20 µg/rat) significantly increased the level of pain in phase 1 of formalin test during proestrus (P=0.000), estrus (P=0.035) and diestrus (P=0.003) stages of estrous cycle (figure 2). Intrahippocampal injection of picrotoxin (30 µg/rat) significantly increased Parvulin the level of pain in phase 1 of formalin test during metestrus (P=0.000) stage of estrous cycle (figure 2). Intrahippocampal injection of picrotoxin (20 and 30 µg/rat) significantly increased the level of pain in phase 2 of formalin test during proestrus (P=0.000), estrus (P=0.000) and diestrus (P=0.000) stages of estrous cycle (figure 2), whereas no significant changes in the level of pain was seen during metestrus (P=1.000) stage of estrous cycle (figure 2).