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Showing 3 results for Opioidergic System

Masoud Fereidoni, Leila Etemadi,
Volume 12, Issue 2 (8-2008)

Introduction: Feverfew (Tanacetum parthenium) (T.p.) is widely used in folk medicine to treat many diseases. We reported the analgesic effect of T.p. flower and leaf previously. Present study is designed to find the mechanism underlying the anti-nociceptive effect of the aqueous extract of T.p. flower. Method: Based on our previous study, the dose 50 mg/kg i.p. of the T.p. aqueous extract had a potent analgesic effect on mice (NMRI) (20 ± 2 g) in formalin test which is used in the present study also. Here, we study the roles of opioidergic, sertoninergic and α - adrenergic systems on the anti-nociceptive effect of the extract. Animals had pretreated with drugs, 15 min before the extract treatments, including opioid antagonist naloxane (5mg/kg, i.p.), sertoninergic antagonist cyproheptadine (4 mg/kg, i.p.) and α-adrenergic antagonist phentolamine (20 mg/kg, i.p.) separately (each group with n≥6). Saline and extract used as controls. Results: In contrast to extract analgesic effect, pretreatment with naloxan increased the pain sensation in the neurogenic phase of formalin test (p<0.001). Pretreatment with cyproheptadine increased the sensation of pain in both early and late phases (p<0.05). Inhibition of α -adrenergic system was not be able to attenuate the anti-nociceptive effect of the extract. Discussion: The involvement of sertoninergic system in anti-nociceptive effect of the T.p. extract is proposed by the results. Also the involvement of opioidergic system has to be mentioned in this effect.
Azam Sadegh, Masoud Fereidoni, Ali Moghimi,
Volume 14, Issue 2 (7-2010)

‎ Introduction: Controversial results have been reported about the effect of morphine and stress on learning and spatial memory in rodents. There are very few studies about the effects of ultra low doses of morphine on memory. In this study, effects of acute administration of low and usual doses of morphine on memory formation and retention in the presence and absence of repeated stress were investigated. Methods: adult male Wistar rats (200-250g) were divided into 3 groups A) Rats were trained for 4 constitutive days and then intraperitoneally received different doses of morphine (1μg/kg, 10μg/kg, 100μg/kg, 1mg/kg and 10mg/kg) 30 minutes before retention test on the 5th day. B) Animals experienced forced swimming stress 30 minutes before each training session for 4 constitutive days and memory retention was evaluated on the 5th and 12th days. C) Rats were treated like animals in group B and then like group A. In all groups, retention tests were done without any excessive treatment on the 12th day. Escape latency and mean path length from the starting point to the platform on training days were considered as learning parameters, while time spent in the target quadrant on the 5th and 12th days was regarded as retention parameter. Results: Memory retention was decreased with 1 μg/kg and 10 mg/kg doses of morphine on the 5th day (P<0.001). Repeated stress led to decreased learning (P<0.001) and retention on the 5th and 12th days (P<0.05). In animals treated with both repeated stress and acute morphine (except for the dose of 1 mg/kg) retention decreased on the 5th day (p<0.001), while retention diminished for all groups on the 12th day. Conclusion: Morphine at usual dose of 10 mg/kg may cause memory retention impairment, by its inhibitory action on the opioidergic system. Surprisingly, morphine at ultra low dose (1 μg/kg) has the same effect and the excitatory action of opioidergic system may be responsible for this effect, however it needs further studies. Repeated stress in combination with morphine even at ineffective dosage could cause memory impairment in the Morris water maze, so the presence of both factors, can probably cause additive impairment of memory
Seyed Sajad Shahrokhi, Manije Karami, Bahram Kazemi,
Volume 15, Issue 3 (10-2011)

Introduction: Response to morphine and role of Nitric Oxide (NO) on expression of morphine response has been studied in vertebrates. But, little evidence is provided in the matter in earlier invertebrates. This investigation for the first time evaluated the effect of NO on expression of morphine potency in Paramecium caudatum. Methods: Animal after isolation from natural media and specific identification was cultured in laboratory. 1 ml of the isolated medium including the animals was added into the Sedgwick– Rafter cell counter. One μl of drugs was infused into the cell counter. Morphine (1-60 μg/μl) was infused into the cell and its effect was recorded throughout 0- 180 sec. L-Arginine (1-8 μg/μl), a NO precursor, was infused prior to morphine (2 μg/μl). The NO producing enzyme was inhibited by preinfusion of L-NAME. Also the naloxone was used to show the involvement of the opioid receptors in the signaling of morphine response. In control speciements distilled water was added solely. Results: The Paramecia under the infusion of morphine were aggregated. The most aggregation rate was observed at a relatively low dose of the drug (2 μg/μl). L-Arginine showed a positive effect on the response (p<0.001) whearas the effect was blocked by preinfusion of the L- NAME. Naloxone showed an inhibitory effect to morphine response. The activity of the NOS was shown by using the NADPH-diaphorase. Conclusion: A sign of morphine potency in single–celled animal is the cell aggregation, and the present results are showing the interaction of NO system with the opioidergic system in this line. On the other hand, concerning the potentiation effect of L-arginine on morphine effective dose in the model, this finding may be useful in reducing of morphine’s side effects in patients under the treatment of the drug, and in the drug economy as well.

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