Opiate system mediate the antinociceptive effects of coriandrum sativum in mice

Our previous study showed that Coriandrum sativum [CS] has antinociceptive effects, but the mechanisms that mediate this effect are not clear. The present study was designed to test the role of opiate system in the antinociceptive effects of CS on acute and chronic pain in mice using Hot Plate [HP], Tail Flick [TF] and Formalin [FT] tests and also to compare its effect with dexamethasone [DEX] and stress [ST]. Young adult male albino mice [25-30 g] in 33 groups [n = 8 in each group] were used in this study. CS [125 250, 500 and 1000 mg/Kg IP], DEX [0.5, 1 and 2 mg/Kg IP], vehicle [VEH] or swim stress were used 30 min before the pain evaluation tests. Acute and chronic pain was assessed by HP, TF and FT models. In addition, Naloxone [NAL, 2 mg/Kg, IP] was injected 15 min before the CS extract administration in order to assess the role of opiate system in the antinociception of CS. Results indicated that CS, DEX and ST have analgesic effects [p < 0.01] in comparison with the control group and higher dose of CS was more effective [p < 0.001]. Besides, pretreatment of NAL modulates the antinociceptive effects of CS in all models [p < 0.001]. The above findings showed that CS, DEX and ST have modulator effects on pain. These findings further indicate that the CS extract has more analgesic effects than DEX and ST and also provides the evidence for the existence of an interaction between antinociceptive effects of CS and opiate system

Effects of Valeriane officinalis, Satureja hortensis and Mentha piperita extracts on the withdrawal syndrome signs in mice

Several studies have demonstrated the antinociceptive, anti-inflammatory, sedative and smooth muscle relaxant activities of the Valeriane Officinalis [VO], Satureja Hortensis [SH], and Mentha Piperita [MP]. The aim of this study was to determine the effects of the aqueous or hydroalcoholic extracts from these plants on morphine withdrawal syndrome signs in mice. 112 male albino mice [25-30 g] were used. Morphine was used to produce drug dependency by Marshall method. Different doses of the aqueous extracts of VO [25, 50, 100 mg/kg] and SH [25, 50, 100, 200 mg/kg IP] and the hydroalcoholic extract of MP [50, 100, 200, 500 mg/kg IP] were injected to morphine-dependent mice 30 min before the naloxone injection [2mg/kg]. Control mice received saline. The severity of the morphine withdrawal responses was estimated by recordeing the number of jumping and the amount of weight feces during 3o min after naloxone injection. The results showed that the extracts of VO [25 mg/kg], SH [200 mg/kg], and MP [all doses] significantly [P<0.05] decreased the number of jumping. Also, the VO [50 and 100 mg/kg], SH and MP [all tested doses] significantly decreased the weight of stool. Our findings indicate that the extracts of VO, SH, and MP may diminish the morphine withdrawal syndrome signs

Antinociceptive effects of hydroalcoholic extract of thymus vulgaris

Previous investigation has shown that Thymus Vulgaris [TV] modulates pain. The aim of this work was to examine the role of TV on acute and chronic pain and compares its effect with dexamethasone [DEX] and stress [ST] by using Hot plate, Tail flick and Formalin tests in mice. In this study male albino mice [25-30 g.] in 21 groups [n = 147] were used. TV [100, 500 and 1000mg/kg], DEX [0.5, 1 and 2 mg/kg] and vehicle [VEH] were injected 30 minutes before pain assessment tests. Stress was applied by 1 min swimming in cold water [18 - 22°]. Acute and chronic pain was assessed by Hot plate, Tail flick and Formalin tests. For assessment of the role of opioid receptors in antinoceception of TV extract, Naloxon [NAL, 2mg/kg, ip] as opioid receptor antagonist was injected before the injection of the more effective dose [500mg/kg] of TV extract. Results indicated that TV, DEX and ST have analgesic effects in all tests [P < 0.01 in comparison with control group]. Above findings showed that TV extract, DEX and ST have modulatory effects on acute and chronic pain. Further research is required to determine the mechanisms by which TV extract has an inhibitory effect on pain sensation

[Evaluation the role nitric oxide in corticosterone effect's on anxiety behaviors in mice]

Many evidence indicated that action of glucocorticoid receptors can modulate anxiety behaviors and these effects probably mediated by nitric oxide [NO] system. Thus, in this study, we investigated interaction between corticosterone and NO on anxiety behaviors in mice in elevated plus maze [EPM]. In this experimental study male albino mice [25-30 g] were used. A standard EPM was used to determine anxiety behaviors. Two behavioral measures were used that include of the percentage of time spent in the open arms and the ratio of open arm entries to total entries during 5 min. Animals received IP injection of L-Name 30 mg/kg as an inhibitor or L-Arginine 50 mg/kg as a synthesis of NO or saline 60 min and corticosterone [1, 2.5, 5 mg/kg] 30 min before of evaluation. Analysis of data indicated that corticosterone at doses of 1 and 2.5, but not 5 mg/kg significantly reduced anxiety behavior in mice [P < 0.05]. Also pretreatment of L-Name potentiate but injection of L-Arginine had inhibition of corticosterone effects [P < 0.05]. This study revealed that glucocorticoid induces anxiolytic effects and these effects probably potentiate by NO inhibitor and reduced by NO synthesis. Therefore, it seems that there are interaction between of glucocorticoid and NO system for control of anxiety behaviors

role of morphine dependence on the level of anxiety in rat

The effects of acute and chronic exposures to opiate drugs on anxiety process are controversial. Acute morphine injection showed the beneficial effects on anxiety. Morphine withdrawal induced severe anxiety response in morphine dependence rats. Whereas, the effects of chronic administrations of morphine on anxiety process are less studied. Furthermore, this study was designed to assess the role of morphine dependence on the level of anxiety in Rat. In this experimental study, Twenty male Wistar rats [250-300 gr] were made dependent by chronic administration of morphine in drinking water that lasted at least 21 days. Control groups received only sucrose in their water. This study utilized the elevated plus-maze model to evaluate anxiogenic-like behavior in rats. Four fundamental behavior patterns were recorded for 5 minutes: the time spent on open arms, the number of entries into open arms, stretched-attend posture and defecation. Immediately after test, the locomotor activity of each animal was tested by using an automated activity monitor system. The data were analyzed by independent t-test and two-way analysis of variance [ANOVA]. Finding indicated that the time spent on open arms and the numbers of entries into open arms were significantly shorter in morphine dependence group than control group [P < 0.05]. Also, the numbers of stretched-attend posture and defecation were significantly higher in morphine group [P < 0.05]. Whereas, there were no significant differences between groups in locomotor activity. This study showed that dependent rats may rapidly predispose anxiogenic- like effects in stressful conditions and without the effect on motor activity

Peripheral injection of dexamethasone modulates anxiety related behaviors in mice: an interaction with opioidergic neurons

Stress and anxiety initiates a cascade of biochemical and endocrine event which results in behavioral and electrophysiological effects in both animals and humans. In this study, we investigated the effects of dexamethasone [DEX], as a synthetic glucocorticoid, and its interaction with opioidergic system on anxiety related behavior in mice. Young adult male mice were used in this study. A standard elevated plus-maze was used to determine anxiety levels in animal. Different doses of DEX [0.1, 0.5, 1, 2 and 10 mg/kg, SC] or vehicle was injected 30 min before of evaluation. Naloxone [1 and 2 mg/kg, IP] was injected 5 min before the DEX [0.5 and 1 mg/kg] administration. Results indicated that DEX at doses of 0.5 and 1 reduced and in dose of 10 mg/kg increased anxiety related behaviors significantly [P < 0.05 in all cases]. Also pretreatment of naloxone at doses of 1 and 2 mg/kg attenuated the effects of lower doses of DEX on anxiety related behaviors. Finding above indicated that peripheral administration of glucoc orticoids induces biphasic effects on anxiety related behaviors: anxiolytic effects in lower doses and anxiogenic effects in a high dose. Data also revealed an involvement of opioidergic system in anxiolytic effects of glucocorticoids